Refine
Is part of the Bibliography
- yes (788)
Year of publication
Document Type
- Doctoral Thesis (410)
- Journal article (362)
- Conference Proceeding (4)
- Preprint (4)
- Master Thesis (3)
- Review (3)
- Habilitation (1)
- Other (1)
Keywords
- Molekularstrahlepitaxie (32)
- Topologischer Isolator (31)
- Quantenpunkt (30)
- Hadron-Hadron scattering (experiments) (29)
- Kernspintomografie (28)
- Parton Distributions (25)
- Photoelektronenspektroskopie (23)
- MRI (20)
- NMR-Tomographie (19)
- Organischer Halbleiter (19)
- ATLAS detector (18)
- NMR-Bildgebung (18)
- physics (18)
- Halbleiter (17)
- Quecksilbertellurid (17)
- ARPES (16)
- Decay (15)
- Drei-Fünf-Halbleiter (15)
- proton-proton collision (15)
- Extension (14)
- Galliumarsenid (14)
- magnetic resonance imaging (14)
- Halbleiterlaser (13)
- Heterostruktur (13)
- Higgs boson (13)
- Nanostruktur (13)
- Optischer Resonator (13)
- quantum dot (13)
- HgTe (12)
- LHC (12)
- Optische Spektroskopie (12)
- Organische Solarzelle (12)
- Rastertunnelmikroskopie (12)
- Spintronik (12)
- Ultrakurzer Lichtimpuls (12)
- ++ (11)
- Dünne Schicht (11)
- Festkörperphysik (11)
- High energy physics (11)
- Physics (11)
- Spektroskopie (11)
- Squark (11)
- molecular beam epitaxy (11)
- Zwei-Sechs-Halbleiter (10)
- topological insulator (10)
- topological insulators (10)
- Elektronischer Transport (9)
- Oberflächenphysik (9)
- Optoelektronik (9)
- Physik (9)
- Raman-Spektroskopie (9)
- Zinkselenid (9)
- Cross-Section (8)
- Einzelphotonenemission (8)
- Elektronenstruktur (8)
- Femtosekundenbereich (8)
- Fotovoltaik (8)
- Grenzfläche (8)
- Organisches Molekül (8)
- Parton distributions (8)
- Rastertunnelmikroskop (8)
- Röntgen-Photoelektronenspektroskopie (8)
- Semimagnetischer Halbleiter (8)
- photoelectron spectroscopy (8)
- semiconductor (8)
- Bildgebendes Verfahren (7)
- Elektronenspin (7)
- Kernspintomographie (7)
- Kondo-Effekt (7)
- LEED (7)
- Laser (7)
- Lunge (7)
- MBE (7)
- Mass (7)
- Quantenwell (7)
- Rekombination (7)
- Röntgenspektroskopie (7)
- Spin-Bahn-Wechselwirkung (7)
- Spintronics (7)
- Supersymmetry (7)
- electronic properties and materials (7)
- quantum dots (7)
- spintronics (7)
- Beyond Standard Model (6)
- Computersimulation (6)
- DFB-Laser (6)
- Exziton (6)
- Exziton-Polariton (6)
- GaAs (6)
- Gluino Production (6)
- Hadron colliders (6)
- Halbleiteroberfläche (6)
- MRT (6)
- Magnetische Kernresonanz (6)
- Magnetismus (6)
- Magnetowiderstand (6)
- Mikroresonator (6)
- Monte-Carlo (6)
- Nanodraht (6)
- Nanopartikel (6)
- Optik (6)
- Perowskit (6)
- Pulsformung (6)
- XPS (6)
- electronic structure (6)
- organic semiconductors (6)
- semiconductors (6)
- Übergangsmetalloxide (6)
- ATLAS (5)
- ATLAS <Teilchendetektor> (5)
- Cadmiumselenid (5)
- Diffusion (5)
- Dotierung (5)
- Dünnschichtsolarzelle (5)
- Elektronenkorrelation (5)
- Elektronenspinresonanz (5)
- Energy (5)
- Halbleiterschicht (5)
- Herz (5)
- Higgs bosons (5)
- MASS (5)
- Magnetische Resonanz (5)
- Magnetischer Halbleiter (5)
- Manganarsenide (5)
- Manganverbindungen (5)
- Molekül (5)
- NMR (5)
- NMR-Spektroskopie (5)
- Oberfläche (5)
- Parallele Bildgebung (5)
- Photoemission (5)
- Photolumineszenz (5)
- Photolumineszenzspektroskopie (5)
- Photovoltaik (5)
- Quanten-Hall-Effekt (5)
- Rashba-Effekt (5)
- Röntgenbeugung (5)
- Silber (5)
- Simulation (5)
- Spin (5)
- Top quark (5)
- XMCD (5)
- atherosclerosis (5)
- energy (5)
- microscopy (5)
- mouse (5)
- nanoparticles (5)
- pulse shaping (5)
- recombination (5)
- semiconductor laser (5)
- solar cells (5)
- spectroscopy (5)
- spin (5)
- Adsorbat (4)
- Aerogel (4)
- Ag(111) (4)
- Aluminiumarsenid (4)
- Biophysik (4)
- Boson (4)
- Breaking (4)
- Diffusionsverfahren <Halbleitertechnologie> (4)
- Distributions (4)
- Elektronengas (4)
- Elektronentransport (4)
- Festkörperoberfläche (4)
- Galliumarsenid-Bauelement (4)
- Galliumarsenidlaser (4)
- Gasionisationsdetektor (4)
- Hierarchy (4)
- Ladungstransport (4)
- Magnetoelektronik (4)
- Magnetresonanztomographie (4)
- Mikroskopie (4)
- NEXAFS (4)
- Nahfeldoptik (4)
- Nanometerbereich (4)
- Nickelverbindungen (4)
- Niederdimensionaler Halbleiter (4)
- Oberflächenzustand (4)
- PTCDA (4)
- Perfusion (4)
- Perovskite (4)
- Perylendianhydrid (4)
- Photochemische Reaktion (4)
- Photostrom (4)
- Plasmon (4)
- Quantendraht (4)
- Quantenkaskadenlaser (4)
- RIXS (4)
- Semiconductor (4)
- Siliciumcarbid (4)
- Sol-Gel-Verfahren (4)
- Solarzelle (4)
- Spin flip (4)
- Strahlungstransport (4)
- Supraleitung (4)
- Top physics (4)
- Topologie (4)
- Wide-gap-Halbleiter (4)
- Wärmeleitfähigkeit (4)
- XRD (4)
- Z boson (4)
- emission (4)
- imaging (4)
- mice (4)
- microcavity (4)
- n-Halbleiter (4)
- optical spectroscopy (4)
- organic solar cells (4)
- plasmonics (4)
- radial (4)
- spin injection (4)
- strong coupling (4)
- superconductivity (4)
- two-dimensional materials (4)
- AFM (3)
- Abstimmbarer Laser (3)
- Adaptivregelung (3)
- Adsorption (3)
- AlGaAs (3)
- Arteriosklerose (3)
- Bosons (3)
- CdSe (3)
- CdTe (3)
- CePt5 (3)
- Compressed Sensing (3)
- Computertomografie (3)
- Coulomb-Blockade (3)
- Cu(111) (3)
- DFB laser (3)
- Diindenoperylen (3)
- Einzelmolekülmikroskopie (3)
- Electroweak interaction (3)
- Elektronenspektroskopie (3)
- Elektronische Eigenschaft (3)
- Events (3)
- Feldeffekttransistor (3)
- Ferromagnetic Semiconductors (3)
- Ferromagnetische Schicht (3)
- Fourier-Spektroskopie (3)
- Frequenzvervielfachung (3)
- Gitterbaufehler (3)
- Graphen (3)
- Hadron Colliders (3)
- Halbleiterphysik (3)
- Herstellung (3)
- Herzmuskel (3)
- Heterostruktur-Bauelement (3)
- Higgs (3)
- Hochauflösendes Verfahren (3)
- Indiumarsenid (3)
- Indiumphosphid (3)
- Kohlenstoff (3)
- Kohärente Kontrolle (3)
- Konfokale Mikroskopie (3)
- Kontrastmittel (3)
- Kraftmikroskopie (3)
- Large Hadron Collider (3)
- Magnetic Anisotropy (3)
- Magnetic resonance imaging (3)
- Magnetischer Röntgenzirkulardichroismus (3)
- Mangan (3)
- Manganate (3)
- Manganselenide (3)
- Mangansilicide (3)
- Maus (3)
- Measuring Masses (3)
- Memristor (3)
- Mikrokavität (3)
- Mikrooptik (3)
- Mikrostruktur (3)
- Model (3)
- Models (3)
- Molecular Beam Epitaxy (3)
- Molekülphysik (3)
- Nanoelektronik (3)
- Nanooptik (3)
- Niederdimensionales Elektronengas (3)
- OLED (3)
- Optical spectroscopy (3)
- Optimierung (3)
- Optische Eigenschaft (3)
- Organic Semiconductors (3)
- Pair Production (3)
- Parallel Imaging (3)
- Particle data analysis (3)
- Photoluminescence (3)
- Photonische Kristalle (3)
- Phthalocyanin (3)
- Physikalische Eigenschaft (3)
- Physikunterricht (3)
- Polymere (3)
- Proton-Proton Collisions (3)
- Quantenkontrolle (3)
- Quantum dots (3)
- Rashba effect (3)
- Rastertunnelspektroskopie (3)
- Regelung (3)
- Rekonstruktion (3)
- Relaxation (3)
- Relaxationszeit (3)
- Relaxometry (3)
- Resonanz-Tunneleffekt (3)
- Röntgenabsorptionsspektroskopie (3)
- Röntgendiffraktometrie (3)
- Röntgenmikroskopie (3)
- STM (3)
- Schwere-Fermionen-System (3)
- Search (3)
- Selbstorganisation (3)
- Spin-Gitter-Relaxation (3)
- Supersymmetric models (3)
- Supraleiter (3)
- Symmetry (3)
- Tissue Engineering (3)
- Transistor (3)
- Transportprozess (3)
- Transportspektroskopie (3)
- Tumor (3)
- W boson (3)
- Weak (3)
- Wärmeübertragung (3)
- Würzburg / Sonderforschungsbereich II-VI-Halbleiter (3)
- Zweidimensionales Material (3)
- absorption (3)
- applied physics (3)
- charge transfer (3)
- computed tomography (3)
- condensed matter physics (3)
- decay (3)
- density functional theory (3)
- diffusion (3)
- dynamics (3)
- exciton (3)
- in vivo imaging (3)
- infrared spectroscopy (3)
- magnetic resonance (3)
- magnetism (3)
- nanostructures (3)
- nuclear magnetic resonance (3)
- optoelectronics (3)
- organic molecule (3)
- organic semiconductor (3)
- parallel imaging (3)
- perfusion (3)
- photoemission (3)
- photoluminescence (3)
- pulse wave velocity (3)
- quantum control (3)
- quantum optics (3)
- quantum physics (3)
- quantum well (3)
- quantum wells (3)
- resonant tunneling diode (3)
- scanning tunneling microscopy (3)
- semiconductor lasers (3)
- single photon emission (3)
- spin-orbit coupling (3)
- states (3)
- surface science (3)
- thermal conductivity (3)
- (Ga (2)
- 3D-Bildgebung (2)
- 4D flow (2)
- Absorptionsspektroskopie (2)
- Algorithm (2)
- Aminosäuren (2)
- Antimonide (2)
- Antimonverbindungen (2)
- Aorta (2)
- Atherosclerosis (2)
- Axion (2)
- Ballistischer Transport (2)
- Bi2Se3 (2)
- Bilderzeugung (2)
- Bildgebung (2)
- Bismuthene (2)
- Bismutselenide (2)
- Bismutverbindungen (2)
- Bose-Einstein-Kondensation (2)
- C60 (2)
- CAIPIRINHA (2)
- CSI (2)
- CT (2)
- Cadmiumsulfid (2)
- Cadmiumtellurid (2)
- Calciumphosphat (2)
- Calciumphosphate (2)
- Cerlegierung (2)
- Coherent control (2)
- Computertomographie (2)
- Constraints (2)
- Cross-section (2)
- CuPc (2)
- Deformation (2)
- Dimension 2 (2)
- Dispersion (2)
- Dreidimensionale Rekonstruktion (2)
- Dreiecksgitter (2)
- Durchblutung (2)
- Dynamik (2)
- EW (2)
- Edelmetall (2)
- Einmodenlaser (2)
- Einzelphotonenquelle (2)
- Electromagnon (2)
- Elektromagnon (2)
- Elektron-Phonon-Wechselwirkung (2)
- Elektronenflüssigkeit (2)
- Elektronenstrahllithographie (2)
- Elektronenzustand (2)
- Energiespeicher (2)
- Epitaxieschicht (2)
- Epitaxy (2)
- European Organization for Nuclear Research. ATLAS Collaboration (2)
- Excitons (2)
- Experimental physics (2)
- Extensions of gauge sector (2)
- FIR-Spektroskopie (2)
- FT-IR-Spektroskopie (2)
- Feldstärkemessung (2)
- Femtosekundenlaser (2)
- Fernsehmaske (2)
- Ferromagnete (2)
- Ferromagnetikum (2)
- Ferromagnetische Halbleiter (2)
- Ferromagnetismus (2)
- Flash-Speicher (2)
- Fluor-19 (2)
- Fluoreszenz (2)
- Fragmentation (2)
- Fullerene (2)
- Funktionswerkstoff (2)
- GRAPPA (2)
- GaMnAs (2)
- Galliumantimonid (2)
- Galliumnitrid (2)
- Gas (2)
- Germanium (2)
- Glas (2)
- Gluino production (2)
- Gold (2)
- Graphene (2)
- H-1-NMR spectroscopy (2)
- HEMT (2)
- HRXRD (2)
- Halbleiter-Supraleiter-Kontakt (2)
- Halbleitergrenzflächen (2)
- Halbmetall (2)
- Herzfunktionsdiagnostik (2)
- Herzinfarkt (2)
- Heusler (2)
- Heuslersche Legierung (2)
- Hochfrequenz (2)
- Hochleistungslaser (2)
- Hochtemperatur (2)
- Hypothetical gauge bosons (2)
- II-VI semiconductor (2)
- II-VI-Halbleiter (2)
- Imaging techniques (2)
- Impact (2)
- Impulslaser (2)
- InP (2)
- Indiumnitrid (2)
- Inelastische Röntgenstreuung (2)
- Inflammation (2)
- Interbandkaskadenlaser (2)
- Interference microscopy (2)
- Isomerizierung (2)
- Jets (2)
- Kardiovaskuläres System (2)
- Kernspinresonanz (2)
- Kohlenwasserstoffe (2)
- Kohärenz (2)
- Kristallfeld (2)
- LEEM (2)
- Ladungstransfer (2)
- Laserdiode (2)
- Lasertechnologie (2)
- Licht-Materie-Wechselwirkung (2)
- Linienbreite (2)
- Lung (2)
- Lungenfunktion (2)
- Luttinger liquid (2)
- Luttinger-Flüssigkeit (2)
- MR (2)
- Magnetic Resonance Imaging (2)
- Magnetic Topological Insulator (2)
- Magnetic resonance (2)
- Magnetische Anisotropie (2)
- Magnetische Eigenschaft (2)
- Magnetit (2)
- Magnetoelektrischer Effekt (2)
- Magnetotransport (2)
- Magnetpartikelbildgebung (2)
- Magnetresonanz (2)
- Magnetresonanztomografie (2)
- Magnon (2)
- Mehrschichtsystem (2)
- Messprozess (2)
- Metall-Isolator-Phasenumwandlung (2)
- Metalloberfläche (2)
- Mice (2)
- Micromegas (2)
- Mikrosäulenresonator (2)
- Mn)As (2)
- Modellbasierte Rekonstruktion (2)
- Modellierung (2)
- Molecular beam epitaxy (2)
- Molekulardynamik (2)
- Monoschicht (2)
- Mott-Isolator (2)
- Multiferroics (2)
- Multiferroikum (2)
- NMR-Mikroskopie (2)
- NTCDA (2)
- Nanostrukturiertes Material (2)
- Nanowire (2)
- Natrium (2)
- Neutrino (2)
- NiMnSb (2)
- Nichtlineare Spektroskopie (2)
- Niederdimensionales System (2)
- ODMR-Spektroskopie (2)
- Oberflächenplasmonresonanz (2)
- Organische Halbleiter (2)
- Organischer Feldeffekttransistor (2)
- Oxygen (2)
- Pair production (2)
- Paralleler Prozess (2)
- Patron Distributions (2)
- Pflanzen (2)
- Photoelectron Spectroscopy (2)
- Photonischer Kristall (2)
- Plants (2)
- Plus plus (2)
- Polariton (2)
- Polariton Lasing (2)
- Poröser Stoff (2)
- Program (2)
- Pulmonary imaging (2)
- Pump-Probe-Technik (2)
- QAHE (2)
- QCD (2)
- Quantenkommunikation (2)
- Quantenoptik (2)
- Quantenpunkte (2)
- Quantenpunktlaser (2)
- Quantentrog (2)
- Quantum anomalous Hall effect (2)
- RHEED (2)
- Raman (2)
- Raman spectroscopy (2)
- Rasterelektronenmikroskopie (2)
- Relaxometrie (2)
- Resonanz-Tunneldiode (2)
- Riesenmagnetowiderstand (2)
- Röntgen-Kleinwinkelstreuung (2)
- Röntgenabsorption (2)
- Röntgenemission (2)
- Röntgenmikroskop (2)
- Röntgenstrahlung (2)
- Röntgenstreuung (2)
- Röntgenstrukturanalyse (2)
- SPA-LEED (2)
- Scanning Tunneling Spectroscopy (2)
- Scanning microscopy (2)
- Scattering (2)
- Semiconductors (2)
- Silicon carbide (2)
- Siliziumcarbid (2)
- Solarzellen (2)
- Spectromicroscopy (2)
- Spin defect (2)
- Spin-Spin-Relaxation (2)
- Spindynamik (2)
- Spinell (2)
- Spininjektion (2)
- Starke Kopplung (2)
- Steady-State Sequences (2)
- Steady-State-Sequenzen (2)
- Störstellen (2)
- Superisolierung (2)
- Surface plasmons (2)
- Surface states (2)
- Symmetry-breaking (2)
- T1-Quantifizierung (2)
- T1rho (2)
- T1ρ (2)
- Technische Optik (2)
- Thermoelektrizität (2)
- Thermometrie (2)
- Thin Films (2)
- Tieftemperatur (2)
- Titan-Saphir-Laser (2)
- Tomografie (2)
- Top-Quark (2)
- Transparent-leitendes Oxid (2)
- Transport (2)
- UPS (2)
- Ultrafast information processing (2)
- Ultrafast spectroscopy (2)
- Ultrakurzzeitspektroskopie (2)
- Ultraviolett-Photoelektronenspektroskopie (2)
- Verbindungshalbleiter (2)
- WSS (2)
- WZ (2)
- Wechselwirkung (2)
- Weiche Röntgenstrahlung (2)
- Wellenleiter (2)
- Wirkungsquerschnitt (2)
- Wärmeisolierstoff (2)
- Wärmeleitung (2)
- Wärmeschutz (2)
- X-ray microscopy (2)
- XES (2)
- Z Boson (2)
- Zeitrichtung (2)
- Zinkoxid (2)
- ZnSe (2)
- Zwischenmolekulare Kraft (2)
- adaptive optimization (2)
- adaptive quantum control (2)
- adsorption (2)
- amino acids (2)
- anisotropy energy (2)
- aortic arch (2)
- balanced SSFP (2)
- ballistic transport (2)
- band structure (2)
- calcium phosphate (2)
- carbon (2)
- carbon nanotubes (2)
- cardiac (2)
- dSTORM (2)
- defects (2)
- diagnosis (2)
- doping (2)
- electrical and electronic engineering (2)
- electron (2)
- epitaxy (2)
- evolutionary algorithm (2)
- excitons (2)
- ferromagnetic semiconductors (2)
- ferromagnetism (2)
- field (2)
- freie Atmung (2)
- gas (2)
- gas phase (2)
- generation (2)
- half metal (2)
- heart (2)
- heat transfer (2)
- helical edge states (2)
- honeycomb lattice (2)
- inflammation (2)
- interband cascade lasers (2)
- interface (2)
- intermolecular interaction (2)
- inverse photoemission (2)
- laser spectroscopy (2)
- lung (2)
- macrophages (2)
- magnetic anisotropy (2)
- magnetic properties and materials (2)
- magnetic susceptibility (2)
- mapping (2)
- materials for optics (2)
- memory (2)
- mesoscopic (2)
- mesoscopics (2)
- metamorphic buffer layer (2)
- model (2)
- modulation spectroscopy (2)
- nano (2)
- nano optics (2)
- nano structure (2)
- nanotechnology (2)
- nanowire (2)
- nanowires (2)
- neutrinos (2)
- nicht-kartesische Bildgebung (2)
- non-Cartesian Imaging (2)
- optics and photonics (2)
- optimization (2)
- organic (2)
- organic light emitting diodes (2)
- organic photovoltaic (2)
- organic photovoltaics (2)
- organic thin films (2)
- organische Halbleiter (2)
- organische Photovoltaik (2)
- oscillations (2)
- oxygen vacancies (2)
- photocurrent (2)
- photoemission spectroscopy (2)
- photon statistics (2)
- phthalocyanine (2)
- pp Collisions (2)
- proton-proton collisions (2)
- proton-proton-collision (2)
- proton–proton collisions (2)
- quantification (2)
- quantum dot laser (2)
- quantum key distribution (2)
- quantum point contact (2)
- quantum spin hall insulator (2)
- qubits (2)
- reconstruction (2)
- resonant photoelectron spectroscopy (2)
- room temperature (2)
- safety (2)
- scanning tunneling spectroscopy (2)
- search (2)
- semiconductor interfaces (2)
- semiconductor quantum dot (2)
- semiconductor quantum dots (2)
- semimagnetic semiconductors (2)
- shadow mask (2)
- signal to noise ratio (2)
- silicon vacancy (2)
- single electron transistor (2)
- sodium (2)
- spin polarization (2)
- spin–orbit coupling (2)
- spontaneous symmetry breaking (2)
- standard model (2)
- superinsulation (2)
- surface state (2)
- surface states (2)
- thermoelectrics (2)
- thermopower (2)
- thin films (2)
- three-dimensional imaging (2)
- transition radiation (2)
- transport (2)
- two-dimensional topological insulator (2)
- vacancy (2)
- verdünnt magnetische Halbleiter (2)
- vicinal surfaces (2)
- wall shear stress (2)
- waveguides (2)
- x-ray emission (2)
- Übergangsmetall (2)
- Übergitter (2)
- "(Ga (1)
- (13)C (1)
- (U)SAXS (1)
- (resonant) photoemission spectroscopy (1)
- + (1)
- 0.2 Tesla (1)
- 1550 nm (1)
- 1994> (1)
- 19F MR (1)
- 19F-MR (1)
- 19F-MRT (1)
- 1H MRI (1)
- 1H MRT (1)
- 2 Jets (1)
- 2 Photon Photoemission (1)
- 2-photon-photoemission (1)
- 23Na (1)
- 23Na-MRT (1)
- 2DEG (1)
- 3 Tesla (1)
- 3D (1)
- 3D Erdfeld-NMR Tomograph (1)
- 3D Pulverdruck (1)
- 3D X-ray microscopy (1)
- 3D analysis (1)
- 3D powder printing (1)
- 3D printing (1)
- 3D reconstruction (1)
- 3D topological insulator (1)
- 3D-Druck (1)
- 4D flow MRI (1)
- 4H (1)
- 8 TEV (1)
- AC Gradients (1)
- AC Stark effect (1)
- AG(110) (1)
- ASAXS (1)
- ATLAS New Small Wheel (1)
- ATLAS New Small Wheels (NSW) (1)
- ATLAS experiment (1)
- ATLAS-Detektor (1)
- AZO (1)
- Aberration (1)
- Abschattung (1)
- Abschirmung (1)
- Absorption (1)
- Abstimmbare Laser (1)
- Abwärmenutzung (1)
- Accelerator modelling and simulations (multi-particle dynamics; single-particle dynamics) (1)
- Acceptor (1)
- Acquisition-weighting (1)
- Acute Myocardial Infarction (1)
- Adaptive Optics (1)
- Adaptive Optik (1)
- Adaptive Optimierung (1)
- Adaptive Quanten Kontrolle (1)
- Adhäsion (1)
- Adiabatische Modenanpassung (1)
- Adsorbate (1)
- Adsorbate System (1)
- Adsorbates (1)
- Adsorbatsystem (1)
- Adsorptionskinetik (1)
- Adsorptionsschicht (1)
- Aerogele (1)
- Ag (1)
- Aharonov-Bohm (1)
- Aharonov-Casher phase (1)
- Aharonov-Casher-Effekt (1)
- Akquisitions-Wichtung (1)
- Aktivierung (1)
- Akzeptor (1)
- Akzeptor <Chemie> (1)
- AlGaInP (1)
- Aluminium-dotiertes Zinkoxid (1)
- Aluminiumoxide (1)
- Ambipolarer Ladungstransport (1)
- Amplifier (1)
- Analogschaltung (1)
- Analyse latenter Strukturen (1)
- Analysis (1)
- Analytische Simulation (1)
- Angle-resolved Photoemission Spectroscopy (1)
- Angular Resolved Photoelectron Spectroscopy (1)
- Anisotrope Diffusion (1)
- Anisotropic Magnetoresistance (1)
- Anisotropie (1)
- Anisotropieenergie (1)
- Anisotropy (1)
- Antenne (1)
- Antiferromagnet (1)
- Antiferromagnetikum (1)
- Antiferromagnetismus (1)
- Aortic arch (1)
- ApoE\(^{(-/-)}\) (1)
- Applied physics (1)
- Array (1)
- Artefakt <Bildgebende Diagnostik> (1)
- Arterial water (1)
- Artery Models (1)
- Asthma (1)
- Atherosclerosis, intracranial arteries (1)
- Atherosklerose (1)
- Atlas detector (1)
- Atom und Molekülphysik (1)
- Atomic (1)
- Atomic Force Microscopy (1)
- Atomic and molecular interactions with photons (1)
- Atomic force microscopy (1)
- Atomketten (1)
- Atomlagenabscheidung (1)
- Atomuhr (1)
- Attosekundenbereich (1)
- Au(111) (1)
- Aufnahmeplanung (1)
- Ausfrieren (1)
- Ausgangsmaterial (1)
- Austausch (1)
- Austauschaufspaltung (1)
- B-0 (1)
- B1 Mapping (1)
- BSG-Laser (1)
- BSM Higgs boson (1)
- BaBiO3 (1)
- Bakterielle Infektion (1)
- Ballistic Transport (1)
- Ballistischer Effekt (1)
- Ballistischer Ladungstransport (1)
- Band edge thermometry (1)
- Bandstruktur (1)
- Bandstrukturberechnung (1)
- Bariumtitanat (1)
- Bathophenanthrolin (1)
- Bauchaorta (1)
- Bauelemente (1)
- Bayerisches Zentrum für Angewandte Energieforschung / Abteilung Wärmedämmung und Wärmetransport (1)
- Bayesian methods (1)
- Berry phase (1)
- Beschichtung (1)
- Bessle functions (1)
- Bestimmung des Relaxations-Parameters in der Magnetresonanztomografie (1)
- Bestrahlung (1)
- Bhabha Scattering (1)
- BiTeBr (1)
- BiTeCl (1)
- BiTeI (1)
- Biegekristalltechnik (1)
- Bienenwolf (1)
- Bilagen-Solarzelle (1)
- Bildqualität (1)
- Bildrekonstruktion (1)
- Bindungsenergie (1)
- Biofabrication (1)
- Biologisches System (1)
- Biomedical engineering (1)
- Bismut (1)
- Bistability (1)
- Blei (1)
- Bloch Siegert (1)
- Bloch oscillations (1)
- Bloch-Siegert (1)
- Blood-brain barrier (1)
- Bornitrid (1)
- Boron Nitride (1)
- Bose-Einstein Correlations (1)
- Bose-Einstein condensation (1)
- Bragg-reflection waveguide (1)
- Brain (1)
- Branching fractions (1)
- Brassica napus (1)
- Breast-tumors (1)
- Breathing (1)
- Bruchfläche (1)
- Bruchmechanik (1)
- Brustaorta (1)
- Buckminsterfulleren (1)
- Bulk-boundary correspondence (1)
- Burst (1)
- By-Light Scattering (1)
- C-13-metabolic flux analysis (1)
- CCIG-Laser (1)
- CCIG-laser (1)
- CERN (1)
- CHIP (1)
- CIGS (1)
- CMR (1)
- CMR-Systeme (1)
- CMR-systems (1)
- CPP-GMR (1)
- CRLs (1)
- Capacitive Effects (1)
- Cardiac (1)
- Cardiovascular Magnetic Resonance (1)
- Cavity quantum electrodynamics (1)
- CdSe/ZnS Nanoteilchen (1)
- CdZnSe/ZnSe (1)
- CeCu6 (1)
- Chambers (1)
- Characterization and analytical techniques (1)
- Charakterisierung (1)
- Charge Carrier Generation (1)
- Charge Carrier Lifetime (1)
- Charge carrier recombination (1)
- Charge-Transfer (1)
- Charged-Particles (1)
- Charges recombination (1)
- Charm quark (1)
- Charmonia (1)
- Chemische Bindung (1)
- Chemische Verschiebung (1)
- Chemischer Austausch (1)
- Chemisorption (1)
- Cherenkov detectors (1)
- Chromoxid <Chrom(IV)-oxid> (1)
- Chronic obstrusive pulmonary disease (1)
- Cluster (1)
- Co (1)
- CoPt (1)
- Codierung (1)
- Coefficient (1)
- Coherent 2D Spectroscopy (1)
- Coherent Control (1)
- Coherent Multidimensional Spectroscopy (1)
- Coherent Two-dimensional Nanoscopy (1)
- Collective effects in quantum optics (1)
- Collicions (1)
- Color (1)
- Color Center (1)
- Combination (1)
- Compressed Sensig (1)
- Computer (1)
- Computerunterstütztes Lernen (1)
- Condensed matter (1)
- Core-shell (1)
- Core-shell Nanoteilchen (1)
- Correlated Electron Materials (1)
- Coulomb interaction (1)
- Coulomb-blockade (1)
- Couplings (1)
- CrO2 (1)
- Crop seed (1)
- Crystal (1)
- CuMnSb (1)
- Cystic fibrosis (1)
- DBR-Laser (1)
- DBR-laser (1)
- DC-Gating (1)
- DECAY (1)
- DFB-laser (1)
- DFT (1)
- DLS (1)
- DLTS (1)
- DMS (1)
- DNMR-Spektroskopie (1)
- DNS (1)
- DNS-Reparatur (1)
- Dark-Matter (1)
- Dark-matter (1)
- Dark-matter production (1)
- Datenspeicher (1)
- Dauerstrichbetrieb (1)
- Decay sequence (1)
- Decays (1)
- Deep Inelastic-scattering (1)
- Defektspektroskopie (1)
- Degradation <Technik> (1)
- Delamination (1)
- Delbruck Scattering (1)
- Density-weighting (1)
- Dependence (1)
- Detektor-Array (1)
- Deterioration (1)
- Diagnostic medicine (1)
- Diamant (1)
- Dichte-Wichtung (1)
- Dichtebestimmung in Theorie und Experiment (1)
- Dichtefunktionalformalismus (1)
- Dichtegewichtete Bildgebung (1)
- Didaktik (1)
- Dielektrikum (1)
- Differential Cross-Sections (1)
- Diffusion model (1)
- Diffusions-MRT (1)
- Diffusionsmodell (1)
- Dilatometrie (1)
- Dilute Nitrides (1)
- Diluted Magnetic Semiconductors (1)
- Diluted magnetic semiconductors (1)
- Dimension 3 (1)
- Dimensional Crossover (1)
- Dimerisierung (1)
- Dirac semimetal (1)
- Disordered semiconductor (1)
- Disperse Phase (1)
- Donor-Acceptor Interface (1)
- Doppeldiode (1)
- Dotierter Halbleiter (1)
- Double-Beta Decay (1)
- Dreidimensionale Bildverarbeitung (1)
- Dreidimensionales Bild (1)
- Dreidimensionales Modell (1)
- Drift-Diffusion (1)
- Drude model (1)
- Drude-Modell (1)
- Durchblutungsmessung (1)
- Durchstrahlungselektronenmikroskopie (1)
- Dynamic Imaging (1)
- Dynamic magnetic resonance imaging (1)
- Dynamical Supersymmetry Breaking (1)
- Dynamics (1)
- Dynamisch-ikonische Repräsentation (1)
- Dynamische Lichtstreuung (1)
- Dynamische MR Bildgebung (1)
- Dynamische Messung (1)
- Dyson orbitals (1)
- Dünnschichten (1)
- Dünnschichttechnik (1)
- Dünnschichttransistor (1)
- E(+)E(-) collicions (1)
- E-Learning (1)
- EDX spectra (1)
- EP Procedures (1)
- EPR Spektroskopie (1)
- EUV (1)
- EXAFS (1)
- Eccentricities (1)
- Echozeit (1)
- Einkristall (1)
- Einzelelektronentransistor (1)
- Einzelphotonenemisson (1)
- Elastische Spannung (1)
- Electrical transport (1)
- Electrochemical energy storage (1)
- Electromagnetic signals (1)
- Electron Paramagnetic Resonance (1)
- Electron Spin Resonance (1)
- Electron Transparency (1)
- Electron density (1)
- Electron spin (1)
- Electronic Structure (1)
- Electronic structure (1)
- Electronics (1)
- Electroweak Measurements (1)
- Electroweak Phase-Transition (1)
- Elektrische Entladung (1)
- Elektrolumineszenz (1)
- Elektromigration (1)
- Elektronen Tunneln (1)
- Elektronenbeugung (1)
- Elektronendichte (1)
- Elektronendichtebestimmung (1)
- Elektronenmikroskopie (1)
- Elektronenstrahllithografie (1)
- Elektronenstreuung (1)
- Elektronische Anregung (1)
- Elektronische Eigenschaften (1)
- Elektronische Korrelationen (1)
- Elektronisches Bauelement (1)
- Elektronisches Rauschen (1)
- Elementarteilchenphysik (1)
- Elementbestimmung (1)
- Emissionsvermoegen (1)
- Energie (1)
- Energieauflösung (1)
- Energiedispersiv (1)
- Energiedispersive Röntgenspektroskopie (1)
- Energielücke (1)
- Energierückgewinnungszeit (1)
- Energies (1)
- Energietechnik (1)
- Energy Harvesting (1)
- Ensemble-Modellierung (1)
- Entanglement (1)
- Envelopefunktionennäherung (1)
- Epitaxie (1)
- Erdfeld (1)
- Erdmagnetismus (1)
- Erzeugung Hoher Harmonischer (1)
- Erzeugung hoher Harmonischer (1)
- Event builder (1)
- Events GW150914 (1)
- Evolutionäre Optimierung (1)
- Evolutionärer Algorithmus (1)
- Excited states (1)
- Excited states spectroscopy (1)
- Exciton (1)
- Exciton-polariton condensate (1)
- Exotic mesons (1)
- Experimental Physics (1)
- Experimental stroke (1)
- Extensions of Higgs sector (1)
- External-Cavity Quantum Cascade Laser (1)
- Externer-Kavitäts-Quanten-Kaskaden-Laser (1)
- Extinktion (1)
- Extrazellularvolumen (1)
- Extremes Ultraviolett (1)
- Exzitonen Diffusionslänge (1)
- Exzitonen Dynamik (1)
- Exzitonen Transport (1)
- Exzitonenbeweglichkeit (1)
- F-19 MRI (1)
- FAIR-ASL (1)
- FDTD (1)
- FDTD Simulation (1)
- FIB (1)
- FIONA (1)
- FTIR spectroscopy (1)
- Fabry-Pérot-Resonator (1)
- Facette (1)
- Facettierung (1)
- Fachdidaktik (1)
- Faraday-Effekt (1)
- Farbzentrum (1)
- Faser (1)
- Faserorientierung (1)
- Fatigue (1)
- Fe3O4 (1)
- FeSi (1)
- Felddetektion (1)
- Femtochemie (1)
- Femtochemistry (1)
- Femtosecond Dynamics (1)
- Femtosecond Laser Pulse Shaping (1)
- Femtosecond Pulse Shaping (1)
- Femtosecond dynamics (1)
- Femtosekunden (1)
- Femtosekunden Dynamik (1)
- Femtosekunden Pulsformung (1)
- Femtosekunden-Laserpulsformung (1)
- Femtosekunden-Laserspektroskopie (1)
- Femtosekundendynamik (1)
- Femtosekundenpulse (1)
- Femtosekundenspektroskopie (1)
- Fermiverteilung (1)
- Ferroelektrikum (1)
- Ferromagnet (1)
- Ferromagnetische Heterostruktur (1)
- Ferromagnetism (1)
- Festkörperspektroskopie (1)
- Festkörpersupport (1)
- Feuchte (1)
- Fiber Orientation (1)
- Field Effect Transistor (1)
- Finite Element Simulationen (1)
- Finite Element Simulations (1)
- Finite-Elemente-Methode (1)
- Flavor Violation (1)
- Flugzeit (1)
- Fluorescence imaging with one nanometer accuracy (1)
- Fluoreszenzkorrelationsspektroskopie (1)
- Fluoreszenzlebensdauer-Mikroskopie (1)
- Fluoreszenzlöschung (1)
- Fluoreszenzmikroskopie (1)
- Fluorophore (1)
- Flussbildgebung (1)
- Flussleiter (1)
- Flüssiger Zustand (1)
- Flüstergaleriemode (1)
- Formaldehyd (1)
- Fortran code (1)
- Fotodetektor (1)
- Fotodetektoren (1)
- Fotophysik (1)
- Fourier-transform spectral interferometry (1)
- Fourier-transform spectroscopy (1)
- Fragmentationsenergie (1)
- Freies Molekül (1)
- Frequenzverdopplung (1)
- Fresnel-Zonenplatte (1)
- Fulleren (1)
- Fullerenderivate (1)
- Functional magnetic resonance imaging (1)
- Functional-NMR Tumor Oxygenation Perfusion Simulation (1)
- Funktionelle NMR-Tomographie (1)
- G8 Bayern (1)
- GAAS (1)
- GAMMA (1)
- GMR (1)
- GaAs/AlGaAs Heterostruktur (1)
- GaAs/AlGaAs heterostructure (1)
- GaAs/Luft-Braggspiegel (1)
- GaAsSb (1)
- GaInNAs (1)
- GaSb (1)
- GaSb/AlAsSb (1)
- GaSb/InAs (1)
- Gallium (1)
- Gallium Manganese Arsenide (1)
- Galliumarsenid-Feldeffekttransistor (1)
- Galliumphosphid (1)
- Gamma (1)
- Gamma-Burst (1)
- Gammablitze (1)
- Gas mixtures (1)
- Gasadsorption (1)
- Gasanalyse (1)
- Gasdruck (1)
- Gaseous Hydrocarbons (1)
- Gaseous detectors (1)
- Gasförmige Kohlenwasserstoffe (1)
- Gasgemisch (1)
- Gasphase (1)
- Gauge bosons (1)
- Gefügekunde (1)
- Gene-expression (1)
- Generation (1)
- Geräuschminderung (1)
- Gewebecharakterisierung (1)
- Giantmagnetoresistance (1)
- Gitterdynamik (1)
- Gittersimulator (1)
- Glatter Krallenfrosch (1)
- Gluon (1)
- Gluon Fusion (1)
- Glycin Peptide (1)
- Glykosylierung (1)
- Gradientensystem (1)
- Gradients (1)
- Graphische Darstellung (1)
- Gravitons (1)
- Grenzflächenchemie (1)
- Grenzflächeneigenschaften (1)
- Grenzflächenleitfähigkeit (1)
- Grenzflächenphysik (1)
- Grenzschicht (1)
- Gunnarsson Schönhammer (1)
- H2Pc (1)
- HARPES (1)
- HE-3 diffusion MRI (1)
- HHG (1)
- HIGGS (1)
- HOMOGENIZED (1)
- HPc (1)
- HREELS (1)
- HRTEM (1)
- Hadron Collider (1)
- Hadron-hadron interactions (1)
- Haftungstest (1)
- Halb-Heusler Legierung NiMnSb (1)
- Halbleiterbauelement (1)
- Halbleiterdiode (1)
- Halbleiterheterostrukturen (1)
- Halbleitersubstrat (1)
- Halbleiter‐Laser (1)
- Halbmetalle (1)
- Half Heusler alloy NiMnSb (1)
- Hard X-ray Angle Resolved Photoemission (1)
- Harmonische (1)
- Harte Röntgenstrahlung (1)
- Hartmannsensor (1)
- Heavy-Particles (1)
- Heißes Elektron (1)
- Helimagnetism (1)
- Hemisphärische Kavität (1)
- Hemodynamics (1)
- Herz-MRT (1)
- Herzbildgebung (1)
- Herzschlag (1)
- Herzshuntdiagnostik (1)
- Heteroepitaxie (1)
- Heteroorganische Monolage (1)
- Heterostructure Growth (1)
- Heterostrukturen (1)
- Hg(1-x)Cd(x)Te (1)
- Hg1-xCdxTe (1)
- Hierarchy problem (1)
- Higgs boson decays (1)
- Higgs boson mass (1)
- Higgs physics (1)
- Higgy-Boson (1)
- High-Energies (1)
- High-Harmonic Generation (1)
- High-Z Oxides (1)
- High-order Harmonic Generation (1)
- Hitzdrahtverfahren (1)
- Hochfeld-NMR (1)
- Hochgeordnete Monolagen (1)
- Hochgeschwindigkeitskinematographie (1)
- Hochmagnetfeld (1)
- Hochtemperatur-Wärmeisolation (1)
- Hofmeister (1)
- Hofmeister-Serie (1)
- Hohe Harmonisch Generation (1)
- Hohe Harmonische (1)
- Hohen-Harmonischen Erzeugung (1)
- Hohlfaser (1)
- Holstein model (1)
- Holstein-Modell (1)
- Hordeum vulgare (1)
- Hot electron (1)
- Hubbard model (1)
- Hubbard-Modell (1)
- Human brain (1)
- Husimi (1)
- Hybridbildgebung (1)
- Hypertonic (1)
- Hypothetical particle physics models (1)
- Hämodynamik (1)
- Hüftkopfnekrose (1)
- IG-FET (1)
- II-IV Halbleiter (1)
- II-VI Semiconductors (1)
- II-VI heterostructures (1)
- II-VI-semiconductor (1)
- II-VI-semiconductors (1)
- III - V Halbleiter (1)
- III - V semiconductors (1)
- III-V semiconductor quantum dot (1)
- III–V semiconductor devices (1)
- IPES (1)
- IR-TrueFISP (1)
- ITO (1)
- Identität (1)
- Image Reconstruction (1)
- Images (1)
- Imaging (1)
- Imaging spin-filter (1)
- Impaktversuche (1)
- Impedance Spectroscopy (1)
- Impedanzspektroskopie (1)
- Implantat (1)
- Impulsformung (1)
- Impulslaserbeschichten (1)
- Impulsmikroskopie (1)
- In situ (1)
- In vivo (1)
- In-vivo (1)
- InAs/GaAs Quantenpunkte (1)
- InAs/GaAs quantum dots (1)
- Incommensurate spin structure (1)
- Indium (1)
- Infarct Zone (1)
- Infarkt (1)
- Infektionsbildgebung (1)
- Information (1)
- Infrarot (1)
- Infrarotemission (1)
- Infrarotspektroskopie (1)
- Inhomogeneities (1)
- Inhomogenität (1)
- Inkommensurable Zykloide (1)
- Insulating thin films (1)
- Insulator surfaces (1)
- Integrated circuit (1)
- Integriert-optisches Bauelement (1)
- Integriertes Lernen (1)
- Interband cascade lasers (1)
- Interesse (1)
- Interface Conductivity (1)
- Interface physics (1)
- Interferenz <Physik> (1)
- Intersubband-Resonanz (1)
- Intrinsic charm (1)
- Inverse Photoemission (1)
- Inverse Photoemissions (1)
- Inverse Probleme (1)
- Inversion Recovery (1)
- Inversion Symmetry Breaking (1)
- Inversionsasymmetrische Halbleiter (1)
- Ionization (1)
- Iridate (1)
- Iron Oxide Nanoparticle (1)
- Iron-oxide (1)
- Iron-uptake (1)
- Irradiation (1)
- Isaac (1)
- Ischämie (1)
- Isomerisierungsreaktion (1)
- Isomerization (1)
- Jaynes-Cummings ladder (1)
- Jena / Institut fuer Optik und Quantenelektronik Jena (1)
- Josephson effect (1)
- Josephson junction (1)
- Josephson junctions (1)
- Josephson-Kontakt (1)
- K* µ+μ− (1)
- KTaO3 (1)
- KWIC (1)
- Kalium (1)
- Kantenzustand (1)
- Kapazität (1)
- Kardio-MRT (1)
- Kationische Lipidbilayer (1)
- Kavitation (1)
- Keramikfaser (1)
- Keramischer Werkstoff (1)
- Kern-Schale-Struktur (1)
- Kernspinrelaxation (1)
- Kernspintomograph (1)
- Kinematik (1)
- Kirchhoff's law (1)
- Knochen (1)
- Knochenstruktur (1)
- Knochenzement (1)
- Koadsorbat (1)
- Kohaerente Optik (1)
- Kohlenwasserstoffsensorik (1)
- Kohärente 2D Spektroskopie (1)
- Kohärente Anregung (1)
- Kohärente Optik (1)
- Kollektivanregung (1)
- Kollektive Anregung (1)
- Kolloider Halbleiter (1)
- Kondensierte Materie (1)
- Kondo (1)
- Kondo-Modell (1)
- Kondo-System (1)
- Kongreß (1)
- Konjugierte Polymere (1)
- Kontamination (1)
- Kontrollierte Wirkstofffreisetzung (1)
- Kooperatives Lernen (1)
- Koppler (1)
- Kopplung von Festkörper- und Gaswärmeleitung (1)
- Koronarperfusion (1)
- Korrelation (1)
- Kosmische Strahlung (1)
- Krach (1)
- Kraft (1)
- Kraftmessung (1)
- Kristall (1)
- Kristallfläche (1)
- Kristalloberfläche (1)
- Kristallwachstum (1)
- Kristallzüchtung (1)
- Künstliche Synapsen (1)
- LAALO3/SRTIO3 interfaces (1)
- LC-Oszillator (1)
- LDOS (1)
- LED (1)
- LHS (1)
- LaAlO3 (1)
- LaAlO3/SrTiO3 (1)
- LaAlO\(_3\)/SrTiO\(_3\) (1)
- LaVO3 (1)
- Laborgerät (1)
- Labormikroskopie (1)
- Ladungsdichtewelle (1)
- Ladungslokalisierung (1)
- Ladungsträger (1)
- Ladungsträgergenerierung (1)
- Ladungsträgerrekombination (1)
- Landau-Niveau (1)
- Lanthanoxid (1)
- Lanthantitanate (1)
- Large detector systems for particle and astroparticle physics (1)
- Laser absorption spectroscopy (1)
- Laserablation (1)
- Laserabsorptionspektroskopie (1)
- Laserarray (1)
- Laserchemie (1)
- Lasererzeugtes Plasma (1)
- Laserspektroskopie (1)
- Laserverstaerker (1)
- Laserverstärker (1)
- Lasing (1)
- Latentwärmespeicher (1)
- Lattice Light-Sheet (1)
- Lautstärkereduktion (1)
- Lead-free double perovskite (1)
- Leerlaufspannung (1)
- Legierungs-Hubbard-Modell (1)
- Legionella (1)
- Legionella pneumophila (1)
- Legionellen (1)
- Legionärskrankheit (1)
- Lehr-Lern-Forschung (1)
- Lehr-Lern-Labor (1)
- Lehramt (1)
- Lehramtsstudierende (1)
- Lehramtsstudium (1)
- Lehranalyse (1)
- Lehrerbildung (1)
- Leistungsverstärkung (1)
- Lepton (1)
- Leptonic (1)
- Leptons (1)
- Lernerfolg (1)
- Lernvideos (1)
- Lesions (1)
- Licht Materie Wechselwirkung (1)
- Lichtinduzierter Effekt (1)
- Lichtwellenleiter (1)
- Light-Matter-Interaction (1)
- Light-Sheet (1)
- Lipid (1)
- Lipidmembran (1)
- Lithografie <Halbleitertechnologie> (1)
- Lithographie <Halbleitertechnologie> (1)
- Lithography (1)
- Localization Microscopy (1)
- Localized states (1)
- Logic Gate (1)
- Logisches Gatter (1)
- Lokales Wachstum (1)
- Long-range order (1)
- Low energy electron microscopy LEEM (1)
- Low temperature effects (1)
- Low-Dimensional Electron Systems (1)
- Low-dimensional molecular metals (1)
- Low-e (1)
- Luminescence (1)
- Lumineszenzdiode (1)
- Lumineszenzlöschung (1)
- Lung Function (1)
- Lung Imaging (1)
- Lung cancer (1)
- Lungenbildbgebung (1)
- Lungenfunktionsprüfung (1)
- Lungenkrebs (1)
- Luttinger liquide (1)
- Lärm (1)
- Lärmbelastung (1)
- MIR spectroscopy (1)
- MIR-Spektroskopie (1)
- MOLLI (1)
- MPGD (1)
- MPI (1)
- MPS (1)
- MR guidance (1)
- MR imaging (1)
- MR microscopy (1)
- MR-MPI-Tomograph (1)
- MR-imaging (1)
- MRI criteria (1)
- MRI reporter (1)
- MRS (1)
- MRT der Lunge (1)
- MU-M (1)
- Ma (1)
- Macroscopic transport (1)
- Magnesiumphosphat (1)
- Magnesiumphosphate (1)
- Magnetfeld-Wechselwirkung (1)
- Magnetfeldsensor (1)
- Magnetic Resonance (1)
- Magnetic Resonance Relaxometry (1)
- Magnetic properties of thin films interfaces (1)
- Magnetic-resonance (1)
- Magnetisch (1)
- Magnetische Anisotropien (1)
- Magnetische Anregung (1)
- Magnetische Halbleiter (1)
- Magnetische Suszeptibilität (1)
- Magnetischer Sensor (1)
- Magnetisierung (1)
- Magneto-Electric Effect (1)
- Magneto-Elektrischer Effekt (1)
- Magneto-optik (1)
- Magneto-optische Eigenschaften (1)
- Magnetoelectric effect (1)
- Magnetometrie (1)
- Magnetometry (1)
- Magnetoresistance (1)
- Magnetpartikelspektroskopie (1)
- Magnetresonanz-Relaxometrie (1)
- Magnetresonanzbildgebung (1)
- Magnetresonanzmikroskopie (1)
- Magnetsensor (1)
- Magnetspule (1)
- Magnetteilchen (1)
- Mahlprozess (1)
- Mais (1)
- Majorana bound state (1)
- Majorana-Nullmoden (1)
- Malaria (1)
- Malignant effusion (1)
- Manganese Silicide (1)
- Manganesesilicide (1)
- Manganion (1)
- Mangansilizid (1)
- Maske (Halbleitertechnologie) (1)
- Mass Spectrum (1)
- Massenspektrometrie (1)
- Massenspektroskopie (1)
- Materialanalytik (1)
- Materials science (1)
- Measurement (1)
- Measuring masses (1)
- Mechanik (1)
- Medicine (1)
- Medizin (1)
- Mehrfach-Solarzelle (1)
- Mehrphotonen-Spektroskopie (1)
- Membranschwingung (1)
- Membranspannung (1)
- Membranviskosität (1)
- Memkondensator (1)
- Meniere’s disease (1)
- Mercury Telluride (1)
- Mercury telluride (1)
- Mesoskopischer Transport (1)
- Mesoskopisches System (1)
- Metall (1)
- Metall-Halbleiter-Kontakt (1)
- Metallcluster (1)
- Metallimplantat (1)
- Metalloxide (1)
- Metallschicht (1)
- Metamaterial (1)
- Methanol (1)
- Metrologie (1)
- Mexico City (1)
- Micelle (1)
- Micro-Hall Magnetometry (1)
- Micro-SQUID (1)
- Microcavities (1)
- Microcavity (1)
- Microcavity devices (1)
- Microresonator (1)
- Microscopy (1)
- Microstructure Modelling (1)
- Microstructure–Property–Relationship (1)
- Mid-infrared photoluminescence (1)
- Mie-Streuung (1)
- Mikro-SQUID (1)
- Mikrocomputertomographie (1)
- Mikrofertigung (1)
- Mikrohallmagnetometrie (1)
- Mikrokavitäten (1)
- Mikrolaser (1)
- Mikroporosität (1)
- Mikroskop (1)
- Mikroskopische Technik (1)
- Mikrospektralanalyse (1)
- Mikrostrukturmodellierung (1)
- Mikrostruktur–Eigenschafts–Korrelationen (1)
- Mikrosystemtechnik (1)
- Mikrotubulus (1)
- Millimeterwelle (1)
- Mischkristall (1)
- Missing Energy (1)
- Mn)As" (1)
- MnSi (1)
- Mode propagation (1)
- Model Based Reconstruction Algorithms in Magnetic Resonance Imaging (1)
- Modellbasierte-Rekonstruktionsalgorithmen in der Magnetresonanztomografie (1)
- Modellbildung (1)
- Moden (1)
- Modenpropagation (1)
- Modulation (1)
- Moelucar beam epitaxy (1)
- Molecular Physics (1)
- Molecular and Optical Physics (1)
- Molecular beam Epitaxy (1)
- Molecular beam epitxy (1)
- Molekularbewegung (1)
- Molekulare Sonde (1)
- Molekularelektronik (1)
- Molekularer Schalter (1)
- Molekularstrahl Epitaxie (1)
- Molekülkontakte (1)
- Molekülorbital (1)
- Molekülspektroskopie (1)
- Molekülsymmetrie (1)
- Molekülzustand (1)
- Momentum- and spin-resolved hard X-ray photoelectron spectroscopy (1)
- Monolage (1)
- Monolayer (1)
- Monte Carlo simulation (1)
- Monte-Carlo-Simulation (1)
- Motivation (1)
- Mott Transistion (1)
- Mott insulator (1)
- Mott-Schottky Analyse (1)
- Mott-Übergang (1)
- Mott–Schottky analysis (1)
- Mouse (1)
- Mouse models (1)
- Multiferroika (1)
- Multimedia (1)
- Multimode-Laser (1)
- Multiple-Scattering (1)
- Multiproteinkomplex (1)
- Muon spectrometers (1)
- Muskelfaser (1)
- Mustervergleich (1)
- Myokardiale Perfusion (1)
- Myokardiale T1ρ-Quantifizierung (1)
- Myon (1)
- NEXAFS spectroscopy (1)
- NIR OLED (1)
- NIXSW (1)
- NLO QCD (1)
- NMR-Imaging (1)
- NMR-Mammographie (1)
- NMR-Spektrometer (1)
- NMR-microscopy (1)
- NMR-spectroscopy (1)
- NNLO (1)
- NSCLC (1)
- Nahfeld Optik (1)
- Nano-Optik (1)
- Nanoantenne (1)
- Nanodot-Speicher (1)
- Nanolithografie (1)
- Nanooptic (1)
- Nanooptics (1)
- Nanoparticles (1)
- Nanoporöser Stoff (1)
- Nanosonde (1)
- Nanostructure (1)
- Nanostructures (1)
- Nanotechnologie (1)
- Nanowires (1)
- Natrium-23 (1)
- Natriumhydroxid (1)
- Natur und Technik (1)
- Natur und Technikunterricht (1)
- Navigator (1)
- Netzwerk (1)
- Neue Physik (1)
- Neuroinformatik (1)
- Neuronale Netzwerke (1)
- Neutrino Mass (1)
- Neutrino detectors (1)
- Neutronenstreuung (1)
- New Small Wheel (1)
- New physics (1)
- Newton (1)
- Nicht-Transparente Medien (1)
- Nicht-kartesische Bildgebung (1)
- Nicht-kleinzelliges Bronchialkarzinom (1)
- Nichtflüchtiger Speicher (1)
- Nichtlineare Optik (1)
- Nichtunterscheidbarkeit (1)
- Niederdimensionale Molekulare Metalle (1)
- Niere (1)
- Nitride (1)
- Non-Cartesian Imaging (1)
- Non-Hermitian skin effect (1)
- Non-transparency (1)
- Nonlinear Dynamics (1)
- Nuclear (1)
- Näherungsverfahren (1)
- OFET (1)
- OLEDs (1)
- OSI (1)
- Oberflächenanalyse (1)
- Oberflächenchemie (1)
- Oberflächenlegierung (1)
- Oberflächenphonon (1)
- Oberflächenplasmon (1)
- Oberflächenplasmonen (1)
- Oberflächenpräparation (1)
- Oberflächenröntgenbeugung (1)
- Oberflächenspannung (1)
- Oil (1)
- Oncolytic virotherapy (1)
- Onedimensional (1)
- Optical Spectroscopy (1)
- Optimale Kontrolle (1)
- Optische Anisotropie (1)
- Optische Antennen (1)
- Optisches Filter (1)
- Orbital (1)
- Orbital Angular Momentum (1)
- Orbitaltomographie (1)
- Ordered metal adsorbates on semiconductor surfaces (1)
- Ordnungs-Unordnungs-Umwandlung (1)
- Organic Light Emitting Diode (1)
- Organic Photovoltaic (1)
- Organic Photovoltaics (1)
- Organic Solar Cells (1)
- Organic and hybrid semiconductors (1)
- Organic semiconductors (1)
- Organik (1)
- Organik-Metall Grenzflächen (1)
- Organische Dünnschichten (1)
- Organische Leuchtdioden (1)
- Organische Moleküle (1)
- Organische Solarzellen (1)
- Organische Verbindungen (1)
- Organischer Stoff (1)
- Oxid (1)
- Oxide (1)
- Oxide Heterostructure (1)
- Oxidhalogenide (1)
- Oxygenierung (1)
- P(P) over-bar collisions (1)
- P(P)over-bar collicions (1)
- P123 (1)
- P3HT (1)
- PB-PB Collisions (1)
- PCM (1)
- PLD (1)
- PP Collicions (1)
- PP collisions (1)
- PT-Transformation (1)
- PUMP (1)
- PWV (1)
- Paarpotentiale (1)
- Pair Prodution (1)
- Pair-Production (1)
- Paneel (1)
- Papier-Solarzelle (1)
- Parallel imaging (1)
- Paramagnetic resonance (1)
- Parametric down-conversion (1)
- Particle accelerators (1)
- Particle dark matter (1)
- Particle physics (1)
- Particle production (1)
- Particle properties (1)
- Particle tracking detectors (Gaseous detectors) (1)
- Particles (1)
- Parton Ditributions (1)
- Patientenkomfort (1)
- Pattern Matching (1)
- PbSnSe (1)
- Peierls-Übergang (1)
- Pentacen (1)
- Peptide (1)
- Perfluorkarbon (1)
- Perfusionsmessung (1)
- Perowskite (1)
- Perowskit‐Halbleiter (1)
- Perowskit‐Solarzellen (1)
- Perturbative QCD (1)
- Pfadintegral (1)
- Pflanzenbildgebung (1)
- Pflanzengewebe (1)
- Phase-encoding (1)
- Phased (1)
- Phasen-Kodierung (1)
- Phasendynamik (1)
- Phasenkohärenz (1)
- Phasenkontrastverfahren (1)
- Phasenraumdarstellung (1)
- Phasenschieber (1)
- Phasenumwandlung (1)
- Phenol-Formaldehyd-Kondensationsprodukt (1)
- Phonon (1)
- Phosphor-31-NMR-Spektroskopie (1)
- Photoanregung (1)
- Photocurrent (1)
- Photodetektor (1)
- Photoemission electron microscopy PEEM (1)
- Photoemission spectroscopy (1)
- Photoemissionselektronenmikroskopie (1)
- Photofragmentation (1)
- Photoisomerisation (1)
- Photoisomerization (1)
- Photolumineszenz Quenching (1)
- Photon detectors for UV, visible and IR photons (vacuum) (1)
- Photonic crystals (1)
- Photonik (1)
- Photons (1)
- Photophysics (1)
- Photophysik (1)
- Photoviltaics (1)
- Phthalocyanine (1)
- Physical Sciences (1)
- Physical sciences (1)
- Physikalische Charakterisierung (1)
- Physikalische Schicht (1)
- Physikalische Zeit (1)
- Physikdidaktik (1)
- Physioloische MRT (1)
- Plasmon propagation (1)
- Plasmonen (1)
- Plasmonics (1)
- Plasmonik (1)
- Plastic electronics (1)
- Pluronic (1)
- Plus (1)
- Plus Plus (1)
- Polarer Halbleiter (1)
- Polarisation (1)
- Polarisationspulsformung (1)
- Polarisiertes Licht (1)
- Polariton-Kondensation (1)
- Polariton-Laser (1)
- Polymerhalbleiter (1)
- Polymerlösung (1)
- Porengröße (1)
- Positionierte Quantenpunkte (1)
- Positionierung (1)
- Predictions (1)
- Production Cross-Section (1)
- Production cross-section (1)
- Professionelle Unterrichtswahrnehmung (1)
- Programm (1)
- Proteins (1)
- Proton-Proton- Collisions (1)
- Proton-Proton-Streuung (1)
- Protonen-NMR-Spektroskopie (1)
- Protons (1)
- Prototype (1)
- Prozessierung (1)
- Präbolus (1)
- Präpolarisationssystems (1)
- Präzisionsmessung (1)
- Pseudorapidity (1)
- Pt (1)
- Pulmonary function (1)
- Pulse Shaping (1)
- Pulse shaping (1)
- Pulsed laser deposition (1)
- Pulswelle (1)
- Pulswellengeschwindigkeit (1)
- Pulver (1)
- Pumpen <Laser> (1)
- Purcell-Effekt (1)
- Pyrolyse (1)
- Pyrometrie (1)
- Q2DEG (1)
- QA-Methode (1)
- QCD Corrections (1)
- QKD (1)
- QW interface profile (1)
- Quanten anomalen Hall-Effekt (1)
- Quanten-Dash (1)
- Quanten-Kontrolle (1)
- Quanten-Monte-Carlo (1)
- Quanten-Spin-Hall-Effekt (1)
- Quantenelektrodynamik (1)
- Quantenfilm (1)
- Quantenkryptologie (1)
- Quantenoptik in Halbleitersystemen (1)
- Quantensensor (1)
- Quantensensorik (1)
- Quantenspinsystem (1)
- Quantentransport (1)
- Quantentrogzustände (1)
- Quantenwell-Laser (1)
- Quantum Control (1)
- Quantum Plasmonics (1)
- Quantum Spin Hall Effect (1)
- Quantum Well (1)
- Quantum Well States (1)
- Quantum chromodynamics (1)
- Quantum chronodynamics (1)
- Quantum confined Stark effect (1)
- Quantum electrodynamics (1)
- Quantum optics with artificial atoms (1)
- Quantum well (1)
- Quantum wells (1)
- Quantum-well, -wire and -dot devices (1)
- Quantumwire (1)
- Quark (1)
- Quark & gluon jets (1)
- Quark pair procuction (1)
- Quarkonium Production (1)
- Quarks (1)
- Quasi-1D Elektronensysteme (1)
- Quasi-eindimensionale Organische Metalle (1)
- Quasiparticle Lifetime (1)
- Quasiteilchen-Lebensdauer (1)
- Quasiteilcheninterferenz (1)
- RAKI (1)
- RECOLA (1)
- REELS (1)
- RF Coil arrays (1)
- RF Coils (1)
- RMnO3 (1)
- RNA-SEQ (1)
- RTD (1)
- Radial Imaging (1)
- Radiale Bildgebung (1)
- Radiation calculations (1)
- Radiative-corrections (1)
- Radikalanionensalz (1)
- Radiologische Diagnostik (1)
- Ramanspektroskopie (1)
- Rapid Prototyping (1)
- Rapidity (1)
- Rare earth manganites (1)
- Rashba (1)
- Rashba-Splitting (1)
- Rastermikroskop (1)
- Rastertunnelspektoskopie (1)
- Rats (1)
- Reaction kinetics and dynamics (1)
- Reaktionskinetik (1)
- Real-time MRI (1)
- Recombination Dynamics (1)
- Reduction (1)
- Reflexion <Physik> (1)
- Reflexionsgeometrie (1)
- Regimes (1)
- Regionales Blutvolumen (1)
- Registrierung <Bildverarbeitung> (1)
- Relativistic heavy-ion collisions (1)
- Relaxation Parameter Mapping in Magnetic Resonance Imaging (1)
- Relaxographie (1)
- Relaxography (1)
- Renewable energies (1)
- Repräsentation (1)
- Repulsion of organic molecules (1)
- Repulsion organischer Moleküle (1)
- Resonante Tunneldioden (1)
- Resonanztunneldiode (1)
- Resonator (1)
- Resonatoren (1)
- Resonators (1)
- Resorcin (1)
- Retrospective Motion Compensation (1)
- Retrospektive Bewegungskorrektur (1)
- Ringresonator (1)
- Rissbildung (1)
- Rissverlauf (1)
- Root s=7 (1)
- Root-S=13 TEV (1)
- Rotary EXcitation (REX) (1)
- Rotary Excitation (1)
- Ru(0001) (1)
- Ruthenium (1)
- Röngenbeugung (1)
- Röntgen-Weitwinkelstreuung (1)
- Röntgendetektor (1)
- Röntgendichroismus (1)
- Röntgenzirkulardichroismus (1)
- SANS (1)
- SARPES (1)
- SAXS (1)
- SEM (1)
- SENSE (1)
- SET (1)
- SET-Transistor (1)
- SHERPA (1)
- SMART (1)
- SQUID (1)
- SRTIO3 (1)
- STED-Mikroskopie (1)
- STO (1)
- STXM (1)
- Salmonella-typhimurium (1)
- Salzlösung (1)
- San Diego <Calif. (1)
- Saphir (1)
- Sauerstoff (1)
- Sauerstoffbegasung (1)
- Sauerstofffehlstellen (1)
- Sb2Te3 (1)
- Scaffold fabrication (1)
- Scale (1)
- Scanning tunneling microscopy (1)
- Schattenmaske (1)
- Schichtsysteme (1)
- Schottky-Kontakt (1)
- Schwache Kopplung (1)
- Schwingungsphase (1)
- Schwingungszustand (1)
- Schüleraktivierung (1)
- Schülerversuch (1)
- Schülervorstellungen (1)
- Seeds (1)
- Sel-MQC (1)
- Selbst-Kalibrierung (1)
- Selbstbild (1)
- Selbstenergie (1)
- Selbstkonzept (1)
- Selbstnavigation (1)
- Self-assembly (1)
- Self-navigation (1)
- Self-organization (1)
- Seltene Erden (1)
- Seltenerdverbindungen (1)
- Semiconductor heterostrctures (1)
- Semiconductor laser (1)
- Semiconductors physics (1)
- Sendedioden (1)
- Sequenzentwicklung (1)
- Shapiro (1)
- Shockley–Read–Hall (1)
- Showers (1)
- Signal Formation (1)
- Silicium (1)
- Silicium Fehlstelle (1)
- Siliciumdioxid (1)
- Siliciumhalbleiter (1)
- Siliciumvakanz (1)
- Silicon Carbide (1)
- Silicon vacancy (1)
- Siliconsuboxide (1)
- Siliziumkarbid (1)
- Simulation methods and programs (1)
- Simultanbildgebung (1)
- Single Molecule Imaging (1)
- Single Molecule Localization Microscopy (1)
- Single Photon Sources (1)
- Single electron transfer (1)
- Single photon emission (1)
- Single-Molecule Transistor (1)
- Single-Photon (1)
- Single-Photon Detectors (1)
- Singlet Fission (1)
- Skalierung (1)
- Skyrmion (1)
- SmB\(_{6}\) (1)
- Soft matter (1)
- Soft-tissue infection (1)
- Sol-Gel-Prozess (1)
- Sol-Gel-Synthese (1)
- Solar Cell (1)
- Solar cell (1)
- Solar energy (1)
- Solar-Cell (1)
- Solartechnik (1)
- Sorption (1)
- Soybean seeds (1)
- Spatially resolved 2D spectroscopy (1)
- Spectroscopy (1)
- Speicher (1)
- Speicherelement (1)
- Speichertransistor (1)
- Spektrale Editierung (1)
- Spektrale Interferenz (1)
- Spektrales Lochbrennen (1)
- Spektromikroskopie (1)
- Spektroskopische Bildgebung (1)
- Spektroskopische Flussmessung (1)
- Spezifische Wärme (1)
- Spin Defekt (1)
- Spin Drehmoment (1)
- Spin Relaxation (1)
- Spin-Bahn-Kopplung (1)
- Spin-Echo (1)
- Spin-Hall-Effekt (1)
- Spin-Injektion (1)
- Spin-LED (1)
- Spin-Ladungs-Umwandlung (1)
- Spin-Lock (1)
- Spin-Orbit Coupling (1)
- Spin-Orbit-Torque (1)
- Spin-Phonon Kopplung (1)
- Spin-Polarisation (1)
- Spin-Transfer-Drehmoment (1)
- Spin-eins-System (1)
- Spin-orbit coupling (1)
- Spin-phonon coupling (1)
- Spindiffusion (1)
- Spindrehmoment Bauteil (1)
- Spinelectronic (1)
- Spinelektronik (1)
- Spinentropie (1)
- Spinflip-Streuung (1)
- Spinkette (1)
- Spinpolarisation (1)
- Spinpolarisierte Rastertunnelmikroskopie, Temperaturabhängige Phasenübergänge (1)
- Spinrelaxation (1)
- Spintronic (1)
- Spinventil (1)
- Spiral imaging (1)
- Spontaneous symmetry breaking (1)
- Sprödbruch (1)
- Spulen (1)
- Spulen-Array (1)
- Sputter deposition (1)
- Stabilisierung (1)
- Standardmodell (1)
- Standardmodell <Elementarteilchenphysik> (1)
- Staphylococcus aureus (1)
- States (1)
- Steifigkeit (1)
- Step Ru surface (1)
- Stiffness (1)
- Stochastische Resonanz (1)
- Storage (1)
- Stoßwelle (1)
- Strahlungskopplung (1)
- Strain (1)
- Strange Baryon Production (1)
- Strom-Spannungs-Kennlinie (1)
- Stromantwort (1)
- Strong interaction (1)
- Strontiumtitanat (1)
- Strontiumvanadate (1)
- Strukturbestimmung (1)
- Strukturbildung (1)
- Student-Lab (1)
- Störstelle (1)
- Störstellenverteilung (1)
- Subject (1)
- Suboxid (1)
- Subwavelength structures (1)
- Sugar-transport (1)
- Supercapacitor (1)
- Superconductor (1)
- Superkondensator (1)
- Superparamagnetic Iron Oxide (1)
- Superparamagnetische Eisenoxid Kontrastmittel (1)
- Superpartners (1)
- Superprisma (1)
- Superradiance & subradiance (1)
- Supersymmetrie (1)
- Supraleiter 2. Art (1)
- Surface (1)
- Surface Raman spectroscopy (1)
- Surface plasmon (1)
- Symmetrie (1)
- Symmetries (1)
- Systembau (1)
- Systems (1)
- Systole (1)
- T1 (1)
- T1 Relaxation (1)
- T1 quantification (1)
- T1-Relaxtion (1)
- T1-Wichtung (1)
- T2 (1)
- T2* (1)
- T2*-Relaxation (1)
- TCSPC (1)
- TGRAPPA (1)
- THz (1)
- TI (1)
- TOSSI (1)
- TSC (1)
- TTF (1)
- TT\(_{1rho}\) mapping (1)
- T\(_{1P}\) dispersion (1)
- T\(_{1P}\) mapping (1)
- Table-top (1)
- Tageslichtelement (1)
- Tageslichtnutzung (1)
- Talbot–Lau interferometer (1)
- Tamm-Plasmonen (1)
- Tau leptons (1)
- Tauola (1)
- Tautomerisation (1)
- Teilchendetektor (1)
- Telekommunikation (1)
- Tensor (1)
- Tensor Tomography (1)
- Terahertz (1)
- Terahertz spectroscopy (1)
- Teststand (1)
- Theorie (1)
- Therapy (1)
- Thermodynamik (1)
- Thermoelektrischer Effekt (1)
- Thermoelektrischer Generator (1)
- Thermokraft (1)
- Thermometry (1)
- Thin film growth (1)
- Thin intermetallic films (1)
- Thiophen (1)
- Thiophenderivate (1)
- TiOPc (1)
- TiO\(_2\) (1)
- Tieftemperatur-Rastertunnelmikroskopie (1)
- Tieftemperaturphänomene (1)
- Tieftemperaturverhalten (1)
- Time hole (1)
- Time measurement (1)
- Time-domain NMR (1)
- Time-of-flight energy recording (1)
- Time-resolved photoemission electron microscopy (1)
- Time-resolved photoluminescence (1)
- To-leading order (1)
- Tool (1)
- Topolectrics (1)
- Topological Insulator (1)
- Topological Insulators (1)
- Topological insulator (1)
- Topological insulators (1)
- Topological metamaterial (1)
- Topologische Laser (1)
- Topologische Supraleitung (1)
- Topology (1)
- Trabekel (1)
- Tracking (1)
- Transient Electrical Methods (1)
- Transiente Absorptionsspektroskopie (1)
- Transitzeitmethode (1)
- Transmission <Physik> (1)
- Transmissionsmikroskopie (1)
- Transporteigenschaft (1)
- Transportmessung (1)
- Transverse-Momentum (1)
- Transverse-momentum (1)
- Traveling Wave Magnetic Particle Imaging (1)
- Triangular lattice (1)
- Tribenzotriquinacen (1)
- Triplett (1)
- Triticeae (1)
- Triticum aestivum (1)
- Tumors (1)
- Tunneldioden (1)
- Tunneleffekt (1)
- Tunneling spectroscopy (1)
- Tunnelkontakt (1)
- Tunnelkontakte (1)
- Tunnelspektroskopie (1)
- Turbo Spin-Echos (1)
- Twin Domains (1)
- Twin Suppression (1)
- Two-color pump-probe spectroscopy (1)
- Two-photon absorption (1)
- Two-photon polymerization (1)
- Type II quantum wells (1)
- Type-II quantum well (1)
- U-Wert (1)
- U-value (1)
- UHECR (1)
- URu2Si2 (1)
- UTE (1)
- UV-VIS (1)
- UV-VIS-Spektroskopie (1)
- Ulrakurze Echozeit (1)
- Ultrafast Spectroscopy (1)
- Ultrafast X-Ray Science (1)
- Ultrafast measurements (1)
- Ultrakurze Laserpulse (1)
- Ultrakurzer Lichtpuls (1)
- Ultrakurzzeit Spektroskopie (1)
- Ultrarelativistic Heavy-Ion (1)
- Ultraschnelle Informationsverarbeitung (1)
- Ultraschnelle Röntgenstrahlung (1)
- Ultraschneller Prozess (1)
- Ultrathin Transmission Target (1)
- Undersampling (1)
- Undulation (1)
- Unterabtastung (1)
- Ununterscheidbarkeit (1)
- Uran (1)
- VCAM (1)
- VCSEL (1)
- VEGF (1)
- VIDE (1)
- VIDED (1)
- VIP (1)
- VIS-Spektroskopie (1)
- Vacuum chambers (1)
- Vakuum (1)
- Vakuumisolationspanel (1)
- Vapor-liquid-solid (1)
- Vascular endothelial Growth Factor (1)
- Vcsels (1)
- Vektorboson (1)
- Vektorfeldformer (1)
- Vektorfeldkontrolle (1)
- Verglasung (1)
- Vergleich (1)
- Vergleichsstudie (1)
- Verstärker (1)
- Verstärkung (1)
- Verteilte Bragg-Reflexion (1)
- Vertikalresonator (1)
- Very strong coupling (1)
- Verzerrung (1)
- Videoanalyse (1)
- Viscosity (1)
- Vizinal (1)
- Volkov-Pankratov states (1)
- Volladdierer (1)
- Volume Reconstruction (1)
- Von-Willebrand-factor (1)
- Vortices (1)
- Vulkanologie (1)
- W & Z bosons (1)
- W(110) (1)
- W-Boson (1)
- WW (1)
- Wabengitter (1)
- Wachstum (1)
- Wachstumsprozess (1)
- Wasserfenster (1)
- Wassertransport (1)
- Waste Heat Recovery (1)
- Weak-Interactions (1)
- Weakly interacting massive particles (1)
- Wechselwirkung intensiver Laserpulse mit Materie (1)
- Weiche Materie (1)
- Wiedemann Franz law (1)
- Wiedemann-Franz-Gesetz (1)
- Wigner (1)
- Wigner-Verteilung (1)
- Winkel- und spin-aufgelöste Photoelektronenspektroskopie im harten Röntgenbereich (1)
- Winkelaufgelöste Photoelektronenspektroskopie (1)
- Winkelaufgelöste Photoemission mit harten Röntgenstrahlen (1)
- Winkelaufgelöste Photoemissionspektroskopie (1)
- Winkelaufgelöste Photoemissionsspektroskopie (1)
- Wire chambers (MWPC, Thin-gap chambers, drift chambers, drift tubes, proportional chambers etc) (1)
- Wurzel (1)
- Wärmeschutzverglasung (1)
- Wärmetransport (1)
- Würzburg / Sonderforschungsbereich Erkennung (1)
- X-Ray Dark-Field (1)
- X-ray (1)
- X-ray analysis (1)
- X-ray imaging (1)
- XANES (1)
- XAS (1)
- XPEEM (1)
- XSW (1)
- Xerogel (1)
- Xylem (1)
- Y-Schalter (1)
- YAG-Laser (1)
- Yu-Shiba-Rusinov-Zustände (1)
- Yukawa coupling (1)
- Zahnimplantat (1)
- Zahnmedizin (1)
- Zeitauflösung (1)
- Zerstörungsfreie Werkstoffprüfung (1)
- Zinc oxide (1)
- Zinn-dotiertes Indiumoxid (1)
- Zirkularpolarisation (1)
- ZnMnSe (1)
- ZnO (1)
- ZnSe heterostructure (1)
- ZnSe-Heterostruktur (1)
- ZnTe (1)
- Zwei-Photonen-Photoelektronenspektroskopie (1)
- Zwei-Photonen-Polymerisation (1)
- Zweiphotonen-Photoemissionsspektroskopie (1)
- Zweiphotonenabsorption (1)
- Zwillingsbildung (1)
- Zwischenschicht (1)
- \(\alpha\)-phase (1)
- \(\beta\)-phase (1)
- aberration (1)
- ablation (1)
- accumulation (1)
- acoustic surface plasmon (1)
- active learning (1)
- adaptive Kontrolle (1)
- adaptive Optimierung (1)
- adaptive Pulsformung (1)
- adaptive Quantenkontrolle (1)
- adaptive control (1)
- adaptive optics (1)
- adaptive pulse shaping (1)
- adiabatic modetransission (1)
- adsoption (1)
- adsorption-induced deformation (1)
- aerogel (1)
- aerogels (1)
- agreement (1)
- alloy (1)
- alloy Hubbard model (1)
- aluminum-zinc-oxide (1)
- alveolar (1)
- anatomical (1)
- anatomisch (1)
- anatomy (1)
- angle resolved photo emission spectroscopy (1)
- angle-resolved photoelectron spectroscopy (1)
- angle-resolved photoemission (1)
- angle-resolved photoemission spectroscopy (1)
- anorganic (1)
- anorganische geordnete Halbleiter (1)
- antiferromagnet (1)
- aorta (1)
- apolipoprotein-E (1)
- applied mathematics (1)
- approximation (1)
- aqueous solution (1)
- array (1)
- arterial elasticity (1)
- artificial synapse (1)
- associated production (1)
- association (1)
- atheriosclerosis (1)
- atmospheric aerosols (1)
- atmospheric chemistry (1)
- atom (1)
- atomar kleine Lücke (1)
- atomic and molecular spectroscopy, (1)
- atomic gases (1)
- atomic-scale gap (1)
- aufdruckbare Solarzellenfarbe (1)
- ballistic (1)
- ballistischer Transport (1)
- ballistisches Transport Regime (1)
- barium titanate (1)
- bathophenanthroline (1)
- binding energy (1)
- biochemical assays (1)
- bioelectrochemistry (1)
- biogeochemistry (1)
- biomaterials (1)
- biomedical engineering (1)
- bismuth (1)
- bistabiles Schalten (1)
- bistable switching (1)
- black carbon (1)
- black-blood (1)
- blazars (1)
- blood (1)
- blood flow (1)
- body weight (1)
- bone cement (1)
- bone imaging (1)
- boron (1)
- boron-nitride (1)
- boson (1)
- brain images (1)
- branched flow (1)
- breaking (1)
- bulk heterojunction (1)
- burried interfaces (1)
- calcium fluoride nanoparticles (1)
- calorimeter (1)
- camelina-sativa (1)
- cantilever-bending technique (1)
- capability (1)
- capacity (1)
- carbon nanotube (1)
- cardiac MRI (1)
- cardiac imaging (1)
- cardiac shunt (1)
- cardiac ventricles (1)
- cardiovascular system (1)
- carrier density (1)
- carrier transport (1)
- carrier-induced ferromagnetism (1)
- catalysis (1)
- catalyst (1)
- catheter tip (1)
- cationic lipid bilayer (1)
- cavity device (1)
- cavity polaritons (1)
- ce compounds (1)
- central carbon metabolism (1)
- central metabolism (1)
- ceramic fibers (1)
- chalcogenide (1)
- chalcogenides (1)
- characterization (1)
- characterization and analytical techniques (1)
- charge (1)
- charge carrier generation (1)
- charge carrier transport in organic thin films (1)
- charge separation (1)
- charge transfer satellites (1)
- charge transfer state (1)
- charge transport (1)
- charged heavy long-lived particles (1)
- chargino (1)
- chemisorption (1)
- children (1)
- circular polarization (1)
- clinically isolated syndromes (1)
- cluster (1)
- cluster dynamical mean-field theory (1)
- coconut cocos-nucifera (1)
- coexistence (1)
- coherence (1)
- coherent control (1)
- coherent imaging (1)
- coherent light (1)
- coherent multidimensional spectroscopy (1)
- coherent potential approximation (1)
- coil (1)
- coil-array (1)
- collective excitation (1)
- color centers (1)
- color tuning (1)
- colour flow (1)
- communication (1)
- comparative study (1)
- complex‐valued machine learning (1)
- compound refractive X-ray lenses (1)
- compound semiconductor (1)
- computed tomography (CT) (1)
- condensed phase (1)
- condensed-matter physics (1)
- confinement (1)
- confocal microscopy (1)
- conjugated polymers (1)
- conjugation (1)
- contact force (1)
- contamination (1)
- contrast-enhanced (1)
- copper (1)
- coronary arteries (1)
- coronene (1)
- correction (1)
- correlated oxides (1)
- correlation (1)
- correlation function (1)
- correlation properties (1)
- cosmic rays (1)
- coulomb coupled quantum dots (1)
- coupler (1)
- coupling of gaseous and solid thermal conduction (1)
- coupling strength (1)
- coupling-constant dependence (1)
- covalent organic framework (1)
- crosslinked coating (1)
- cryo deposition (1)
- cryogenic temperature (1)
- crystal (1)
- crystal growth (1)
- crystalline (1)
- current response (1)
- cystic fibrosis (1)
- dark matter (1)
- darkfield imaging (1)
- data augmentation (1)
- daylighting (1)
- decays (1)
- deep learning (1)
- deformation (1)
- delamination (1)
- delocalization (1)
- density functional calculations (1)
- density weighted imaging (1)
- density weighting (1)
- density-functional theory (1)
- dental implant (1)
- detected magnetic-resonance (1)
- developing oilseeds (1)
- developmental signaling (1)
- devices (1)
- devices for energy harvesting (1)
- dewatering (1)
- dfb-laser (1)
- diabolical points (1)
- diboson production (1)
- dichteangepasste k-Raum Abtastung (1)
- dielectric oxides (1)
- diffraction (1)
- diffusion tensor imaging (1)
- digital Lock-In (1)
- digitaler Lock-In (1)
- diindenoperylene (1)
- dilatometer (1)
- dilute magnetic semiconductors (1)
- dilute nitride (1)
- diluted magnetic Semiconductor (1)
- diluted magnetic semiconductors (1)
- diode laser (1)
- diphoton decay (1)
- diphoton events (1)
- disease (1)
- dispersion (1)
- distant dipolar field (1)
- distributions (1)
- disturbance (1)
- dot (1)
- downconversion (1)
- dreMR (1)
- dressed states (1)
- droplet epitaxy (1)
- dynamic imaging (1)
- dynamic light scattering (1)
- dynamic-iconic representation (1)
- dynamical mean field (1)
- dynamische Bildgebung (1)
- dynamische Lichtstreuung (1)
- dysfunction (1)
- dünne intermetallische Filme (1)
- e(+)e(-) Collisions (1)
- echo time (1)
- economic growth (1)
- edge states (1)
- eindimensionale Systeme (1)
- electrical excitation (1)
- electrically driven (1)
- electrically triggered (1)
- electrochemistry (1)
- electromagnetic calorimeter (1)
- electromagnon (1)
- electromigration (1)
- electron beam lithography (1)
- electron tunneling (1)
- electron-hole scattering (1)
- electron-vibration coupling (1)
- electronic and spintronic devices (1)
- electronic correlations (1)
- electronic coupling (1)
- electronic phase transitions (1)
- electronic transport (1)
- electronic transport in nanocrystalline materials (1)
- electrostatics (1)
- electroweak production (1)
- elektrische Anregung (1)
- elektronische Struktur (1)
- embryo (1)
- emphysema (1)
- emulsions (1)
- energetic jet (1)
- energies (1)
- energy storage (1)
- energy-dispersive (1)
- enhanced green fluorescent protein (1)
- ensemble modeling (1)
- entanglement (1)
- envelope function approximation (1)
- environmental sciences (1)
- epitaxial structures (1)
- epr spectroskopy (1)
- evolutionary optimization (1)
- evolutionärer Algorithmus (1)
- exchange (1)
- exciplexes (1)
- excitations (1)
- excited electrons (1)
- exciton binding energy (1)
- exciton blocking layer (1)
- exciton-polariton (1)
- exciton-polariton condensates (1)
- exciton‐polaritons (1)
- experimental and theoretical determination of electron density (1)
- explanatory videos (1)
- explosive volcanism (1)
- explosiver Vulkanismus (1)
- extrinsic (1)
- extrinsisch (1)
- facet (1)
- faceting (1)
- far-infrared spectroscopy (1)
- fatigue (1)
- femtosecond (1)
- femtosecond laser spectroscopy (1)
- femtosecond pulse shaping (1)
- femtosecond pulses (1)
- fermions (1)
- ferroelectricity (1)
- ferromagnet (1)
- ferromagnetic resonance (1)
- ferromagnetische Halbleiter (1)
- ferromagnetische Resonanz (1)
- ferromagnets (1)
- field free point (FFP) (1)
- field-effect transistor (1)
- films (1)
- flash memory (1)
- floating gate transistor (1)
- flow (1)
- flow dynamics (1)
- flow patterns (1)
- fluorescence (1)
- fluorescence imaging (1)
- fluorescence microscopy (1)
- fluorine (1)
- flux balance analysis (1)
- flux guides (1)
- flüssige Phase (1)
- four-wave mixing (1)
- fourier transform spectroscopy (1)
- fragmentation (1)
- fragmentation energy (1)
- fragmentation functions (1)
- free breathing (1)
- free electron laser (1)
- free respiration (1)
- free space (1)
- frequency combs (1)
- fs (1)
- full adder (1)
- full-field microscopy (1)
- fully hadronic (1)
- functional (1)
- functional magnetic resonance imaging (1)
- funktionell (1)
- funktionelle Lungenbildgebung (1)
- funktionelle MRT (1)
- g-Faktor (1)
- g-Wert (1)
- g-value (1)
- gain (1)
- gallium nitride (1)
- gallium phosphide (1)
- gamma gamma channel (1)
- gamma radiation (1)
- gamma-ray bursts (1)
- gapless Andreev bound states (1)
- gas adsorption (1)
- gasb (1)
- gekoppelte Kavitäten (1)
- geminale Rekombination (1)
- gene alleles (1)
- gene family evolution (1)
- gene-expression data (1)
- geometrische Struktur (1)
- geordnete Metalladsorbate auf Halbleiteroberflächen (1)
- glycine peptides (1)
- grain boundaries (1)
- grand unification (1)
- graphene (1)
- grating interferometer (1)
- grating interferometry (1)
- gravitational waves (1)
- group refractive index (1)
- growth (1)
- guidelines (1)
- h-dimerization (1)
- hadron colliders (1)
- hadronic Recoil (1)
- hadronic decays (1)
- hadronischer Rückstoß (1)
- half-Heusler (1)
- halfmetals (1)
- halogenation (1)
- hard double-patron interactions (1)
- hard x-ray photoemission (1)
- harmonic (1)
- heart rate (1)
- heat conversion (1)
- heat currents (1)
- heating (1)
- heavy fermion insulators (1)
- heralded entanglement (1)
- heterogen (1)
- heterogeneous (1)
- heteromolecular interfaces (1)
- heterorganic monolayer (1)
- heterostructures (1)
- heterotrophic arabidopsis cells (1)
- heterovalent heterointerfaces (1)
- hidden-beauty states (1)
- high contrast (1)
- high energy physics (1)
- high field (1)
- high field MRI (1)
- high field NMR (1)
- high harmonic generation (1)
- high power laser (1)
- high temperature (1)
- high temperature thermal insulation materials (1)
- high transverse momentum jets (1)
- high-energy collider experiment (1)
- high-harmonic generation (1)
- high-intensity laser-matter interaction (1)
- high-order finite element (1)
- high-order harmonic generation (1)
- high-power laser (1)
- high-speed photography (1)
- high-throughput (1)
- histology (1)
- hochauflösende Bildgebung (1)
- hochauflösende Elektronenbeugung (1)
- hole (1)
- hole-burning (1)
- hubbard-model (1)
- hybrid imaging (1)
- hydrocarbons (1)
- hydrogen (1)
- hyperpolarized HE-3 (1)
- illumination (1)
- image processing (1)
- image quality (1)
- image reconstruction (1)
- imaging agents (1)
- imaging techniques (1)
- impact experiments (1)
- impedance spectroscopy (1)
- impurities (1)
- in vivo MR-Spektroscopy (1)
- in-line phase contrast (1)
- in-situ (1)
- inclusive cross section (1)
- inctracellular (1)
- indium phosphide (1)
- indium-tin oxide (1)
- induced (1)
- induced phase transition (1)
- induced superconductivity (1)
- infants (1)
- infarct (1)
- infarction (1)
- infection (1)
- inorganic LEDs (1)
- instrumentation (1)
- insulator (1)
- integral (1)
- integrated circuits (1)
- integrated optics (1)
- interband cascade laser (1)
- interface conductivity (1)
- interface properties (1)
- interfaces (1)
- intermixing (1)
- intermolecular zero-quantum coherence (1)
- interplay of surface states (1)
- intersubband resonance (1)
- intrazellulär (1)
- intrinsic (1)
- intrinsisch (1)
- ion-specific effects (1)
- ionenspezifische Effekte (1)
- iron oxide contrast agent (1)
- iron pnictides (1)
- isomerization (1)
- jet energy scale (1)
- jet production (1)
- jet shapes (1)
- jets (1)
- josephson junction (1)
- kardiale MRT (1)
- keV (1)
- keramische Fasern (1)
- kinematics (1)
- kink instability (1)
- komplexe Gitterkopplung (1)
- kondensierte Phase (1)
- konjugiert (1)
- laboratory (1)
- lamellar micelles (1)
- large artery vasculitis (1)
- large optical cavity (1)
- laser (1)
- laser array (1)
- laser physics (1)
- lasers (1)
- lasing (1)
- latent heat (1)
- lead-lead collision (1)
- learning (1)
- lesion size (1)
- lesions (1)
- lifetimes (1)
- lift-off (1)
- light (1)
- light matter coupling (1)
- light scattering and absorption (1)
- light sources (1)
- light-matter interaction (1)
- light–matter interaction (1)
- lineage-specific genes (1)
- linear combination (1)
- lipid biosynthesis (1)
- lipid imaging (1)
- liquid cell (1)
- liquid phase (1)
- liquid-metal-jet (1)
- liquid-metal-jet anode X-ray source (1)
- liquids (1)
- local density (1)
- local supersymmetry (1)
- localized surface plasmon (1)
- long-lived neutral particle (1)
- low-emissivity coating (1)
- low-temperature magnetotransport (1)
- low-valent compounds (1)
- magnesium phosphate (1)
- magnetic (1)
- magnetic dopants (1)
- magnetic field relaxation (1)
- magnetic nanoparticles (1)
- magnetic oxide (1)
- magnetic properties (1)
- magnetic resonance imaging (MRI) (1)
- magnetic semiconductors (1)
- magnetic sensor (1)
- magnetic topological insulator (1)
- magnetic-resonance behavior (1)
- magnetische Anisotropie (1)
- magnetization (1)
- magnetized sphere/cylinder (1)
- magneto optics (1)
- magneto-optical properties (1)
- magnetometry (1)
- magnetoresistance (1)
- magnetoresistive effect (1)
- magnetoresistiver Effekt (1)
- magnetotransport (1)
- maize kernels (1)
- mapping function (1)
- maser (1)
- mass spectrocopy (1)
- materials design (1)
- matrix element effects (1)
- mbe (1)
- mean-field theory (1)
- mechanic (1)
- mechanical stiffness (1)
- mechanische Steifigkeit (1)
- mechanisms (1)
- medical device (1)
- medical imaging (1)
- melt electrowriting (1)
- membrane tension (1)
- membrane viscosity (1)
- memristive Funktionen (1)
- memristive functions (1)
- mercury (1)
- mesoscopic transport (1)
- mesoskopisch (1)
- mesoskopischer Transport (1)
- metabolism (1)
- metal surfaces (1)
- metal-insulator transition (1)
- metal-organic (1)
- metal-to-insulator transition (1)
- metall-organisch (1)
- metals (1)
- methanofullerenes (1)
- micro cavity (1)
- micro pattern gaseous detectors (1)
- micro-photoluminescence (1)
- microlaser (1)
- micromegas detectors (1)
- microresonator (1)
- microresonators (1)
- microscope (1)
- microstructure (1)
- microtomography (1)
- mid-infrared (1)
- mid-infrared sensing (1)
- mid-infrared wavelength applications (1)
- milling process (1)
- mixing state (1)
- mo (1)
- mobility (1)
- mode (1)
- mode matching (1)
- mode matching method (1)
- model Bessel function (1)
- model calculation (1)
- modeling (1)
- modelling (1)
- moisture (1)
- molecular Dynamics (1)
- molecular contacts (1)
- molecular doping (1)
- molecular electronics (1)
- molecular imaging (1)
- molecular movie (1)
- molecular transport (1)
- molecule (1)
- molecule-metal interfaces (1)
- molekulare Dynamik (1)
- molekulare Elektronik (1)
- mono-mode laser (1)
- monodispersity (1)
- monolayers (1)
- monolithic grating (1)
- monomodige Laser (1)
- morphometry (1)
- motivation (1)
- mott insulator (1)
- mouse models (1)
- mram (1)
- multi-messenger physics (1)
- multi-spin flip (1)
- multi-terminal devices (1)
- multichromophores (1)
- multiferroics (1)
- multifunctional nanoparticles (1)
- multilayer (1)
- multimodal imaging (1)
- multiple Botenteilchen (1)
- muon (1)
- muon spectrometer (1)
- muons (1)
- muscle fiber (1)
- myocardial infarction (1)
- n-doping (1)
- nano CT (1)
- nano-CT (1)
- nanoactivity (1)
- nanoantenna (1)
- nanoelectronic (1)
- nanoelectronics (1)
- nanographenes (1)
- nanolithography (1)
- nanoparticle (1)
- nanophotonics (1)
- nanophotonics and plasmonics (1)
- nanoscience and technology (1)
- nanostructured (1)
- narrow-gap semiconductor (1)
- near-IR chromophores (1)
- near-field optics (1)
- near-gap spectra (1)
- neural networks (1)
- neutralino (1)
- neutron reflectometry (1)
- new physics (1)
- nexafs (1)
- nicht-diagonale langreichweitige Ordnung (1)
- nichtgeminale Rekombination (1)
- nichtkarthesische Bildgebung (1)
- nichtlinearer Magnetotransport (1)
- niederdimensionale Elektronensysteme (1)
- niedrigemittierende Beschichtung (1)
- noise and multimode dynamics (1)
- non-Cartesian imaging (1)
- non-Cartesian trajectories (1)
- non-classical light (1)
- non-destructive testing (1)
- non-triggered (1)
- nondestructive testing (1)
- nonlinear dynamics (1)
- nonlinear magnetotransport (1)
- nonlinear optics (1)
- nonlinear spectroscopy (1)
- non‐fullerene acceptors (1)
- ntcda (1)
- nuclear magnetic resonance spectroscopy (1)
- nuclear power (1)
- number (1)
- obstructive pulmonary disease (1)
- oil storage (1)
- oilseeds (1)
- oligo-DNA (1)
- oncolytic viruses (1)
- one-dimensional (1)
- one-dimensional systems (1)
- open circuit voltage (1)
- optical (1)
- optical antenna (1)
- optical antennas (1)
- optical lattice (1)
- optical physics (1)
- optical polarization conversion (1)
- optical resonator (1)
- optics (1)
- optimale Teilchendurchmesser (1)
- optimum particle diameter (1)
- optisch (1)
- opto electronics (1)
- optoelectronic devices (1)
- optoelektronische Bauelemente (1)
- orbital imaging (1)
- orbital tomography (1)
- organic bulk heterojunction solar cell (1)
- organic field-effect transistor (1)
- organic molecules (1)
- organic semicondcutors (1)
- organic thin-films (1)
- organic thin‐film transistors (1)
- organic-inorganic hybrid nanostructures (1)
- organic-metal interfaces (1)
- organic–metal interface (1)
- organische Solarzellen (1)
- organische ungeordnete Halbleiter (1)
- oscillating biomagnetic fields (1)
- oscillator strengths (1)
- output elasticities (1)
- oxide (1)
- oxide heterostructure (1)
- oxide heterostructures (1)
- oxides (1)
- oxidische Heterostruktur (1)
- oxygen-enhanced (1)
- p-Halbleiter (1)
- pair potentials (1)
- pair production (1)
- paramagnetic resonance (1)
- parity (1)
- particle (1)
- partizipierende Medien (1)
- passivation (1)
- patterning (1)
- pentacene (1)
- performance (1)
- perovskite solar cells (1)
- perovskites (1)
- perylene dyes (1)
- phase change material (1)
- phase coherence (1)
- phase contrast (1)
- phase contrast imaging (1)
- phase dynamics (1)
- phase retarder (1)
- phase stepping (1)
- phase transition (1)
- phase transitions and critical phenomena (1)
- phase-change (1)
- phase-contrast CMR (1)
- phase-contrast MRI (1)
- phase-space-representation (1)
- phased (1)
- phased-array (1)
- phasematching (1)
- phenolic resin (1)
- phonon (1)
- phosphorescence (1)
- phosphorus (1)
- photo-CELIV (1)
- photochemical air-pollution (1)
- photoelectron spectrocsopy (1)
- photoelectron spectrscopy (1)
- photoinduced transport (1)
- photoinduzierter Transport (1)
- photoluminescence excitation (1)
- photoluminescence spectroscopy (1)
- photon (1)
- photon bunching (1)
- photon counting (1)
- photon lasing (1)
- photonic crystal (1)
- photonic crystals (1)
- photonic devices (1)
- photonic dot (1)
- photonics (1)
- photonische Kristalle (1)
- photonischer Punkt (1)
- photon‐correlation (1)
- photoreflectance (1)
- photosensor (1)
- physical characterisation (1)
- physical chemistry (1)
- physical sciences (1)
- physical time (1)
- physics education (1)
- physics transition (1)
- pi-conjugated (1)
- pinned orbital moments (1)
- plant reproduction (1)
- plant roots (1)
- plaque (1)
- plaque characteristics (1)
- plasmon (1)
- plasmon group velocity (1)
- plasmonic waveguides (1)
- plasmons (1)
- point emitters (1)
- polarition condensate (1)
- polariton (1)
- polariton condensation (1)
- polariton laser (1)
- polaritons (1)
- polarization (1)
- polarization pulse shaping (1)
- polaron delocalization (1)
- polyacene (1)
- polymer electrolytes (1)
- polymer thermoelectrics (1)
- polymers (1)
- population inversion (1)
- population oscillations (1)
- pore size (1)
- porous (1)
- porös (1)
- power gain (1)
- pp collisions (1)
- pre-service teachers (1)
- prebolus (1)
- prefrontal cortex (1)
- printed paper photovoltaics (1)
- processing (1)
- professional vision (1)
- program (1)
- proton (1)
- proton MRI (1)
- proton-lead collision (1)
- proton-proton-collisions (1)
- proton-proton-collistion (1)
- proton-prton-collision (1)
- proximity effect (1)
- pulse-wave velocity (1)
- pulsed ODMR (1)
- pulswave velocity (1)
- pyrolysis (1)
- quantitative MRI (1)
- quantitative computed tomography (1)
- quantitative epr (1)
- quantized vortices (1)
- quantum Monte Carlo (1)
- quantum billiard (1)
- quantum communication (1)
- quantum communications (1)
- quantum dash (1)
- quantum dot systems (1)
- quantum gases (1)
- quantum information (1)
- quantum information technology (1)
- quantum interference (1)
- quantum mechanical coupling (1)
- quantum mechanics (1)
- quantum metrology (1)
- quantum optics in semiconductors (1)
- quantum repeaters (1)
- quantum sensing (1)
- quantum spin Hall effect (1)
- quantum transport (1)
- quantum wire (1)
- quantum-dots (1)
- quantum-well -wire and -dot devices (1)
- quantum-well laser (1)
- quantumcascade laser (1)
- quasi-one-dimensional organic metals (1)
- radiation (1)
- radiation transport (1)
- radiative coupling (1)
- radical (1)
- radioactive waste (1)
- radiofrequency ablation (1)
- ray (1)
- reaction cross section (1)
- rectification (1)
- redispergierte Nanopartikel-Sole (1)
- redispersed nanoparticle sol (1)
- registration (1)
- repositories (1)
- resistance (1)
- resistive micromegas (1)
- resolution enhancement (1)
- resonance (1)
- resonances (1)
- resonant inelastic x-ray scattering (1)
- resonant scattering (1)
- resonant tunneling (1)
- resonant tunneling diodes (1)
- resonante Streuung (1)
- resonante Tunneldioden (1)
- resonator (1)
- resonators (1)
- retrospective (1)
- robust (1)
- rotating magnetic field (1)
- s-Channel (1)
- s-shape (1)
- sFLIM (1)
- saccharomyces cerevisiae (1)
- saccotomy (1)
- salt solutions (1)
- samarium hexaboride (1)
- sapwood (1)
- scanning (1)
- scattering characteristics (1)
- secondary phases (1)
- seed (1)
- seed aging (1)
- seed quality (1)
- seeds (1)
- selected area growth (1)
- selective multiple quantum filter (1)
- selektiver Mehrquantenfilter (1)
- self-assembled monolayer (SAM) (1)
- self-assembly (1)
- self-calibration (1)
- self-concept (1)
- self-diffusion (1)
- self-gating (1)
- self-navigation (1)
- semi-magnetic (1)
- semiconductor microavity (1)
- semiconductor surfaces (1)
- semileptonic & radiative decays (1)
- semimagnetic semiconductor (1)
- semimagnetisch (1)
- shape-truncation functions (1)
- shear viscosity (1)
- shocks (1)
- side-peak emission (1)
- single crystal (1)
- single crystalline (1)
- single electron transport (1)
- single molecule microscopy (1)
- single photon (1)
- single quantum dot (1)
- single top quark (1)
- single-crystalline Ru surfaces (1)
- single-electron tunneling (1)
- single-photon detectors (1)
- single-photon source (1)
- single-top-quarks (1)
- singlet (1)
- site-controlled (1)
- site-controlled quantum dot (1)
- site-controlled quantum dots (1)
- small animal (1)
- soft x-ray (1)
- soft x-ray photoemission (1)
- software (1)
- sol gel (1)
- sol-gel process (1)
- sol-gel-technology (1)
- solar cell (1)
- solar glazing (1)
- solid state physics (1)
- solid support (1)
- solitons (1)
- sorption (1)
- spatially resolved photoluminescence (1)
- specific heat (1)
- spectra (1)
- spectral editing (1)
- spectral interferometry (1)
- spectroscopic imaging (1)
- spektroskopie (1)
- spezifische Absorptionsrate (1)
- spin Hall effect (1)
- spin Injektion (1)
- spin dephasing (1)
- spin entropy (1)
- spin label (1)
- spin labeling (1)
- spin lock (1)
- spin physics (1)
- spin relaxation (1)
- spin torque (1)
- spin torque device (1)
- spin transport (1)
- spin valve (1)
- spin-flip Raman spectroscopy (1)
- spin-lock (1)
- spin-orbit-coupling (1)
- spin-orbit-interaction (1)
- spin-orbit-torque (1)
- spin-phonon coupling (1)
- spin-resolved ARPES (1)
- spin-transfer torque (1)
- spindiffusion (1)
- spindynamic (1)
- spindynamics (1)
- spinflip scattering (1)
- spinpolarized scanning tunneling microscopy, temperature dependent phase transitions (1)
- spintronic (1)
- spintronik (1)
- standard semiconductor laser (1)
- standing wave formation (1)
- steady-state free precession (1)
- steam (1)
- stehende Röntgenwellenfelder (1)
- stenosis (1)
- steps (1)
- stimulated (1)
- stimulated echo (1)
- stimulated emission (1)
- stimuliertes Echo (1)
- structure determination (1)
- students' conceptions (1)
- sub-micron (1)
- sub-mikrometer (1)
- subcutaneous implanation (1)
- sucrose allocation (1)
- super-resolution (1)
- superconductors (1)
- supercritical CO<sub>2</sub> (1)
- supercurrent (1)
- superfluid (1)
- supergauge transformations (1)
- superparamagnetische Eisenoxid Kontrastmittel (1)
- superprism (1)
- superradiance (1)
- superradiant pulse emission (1)
- supersymmetry (1)
- surface (1)
- surface collisions (1)
- surface morphology (1)
- surface plasmon (1)
- surface preparation (1)
- surface roughness (1)
- surface stress (1)
- surgical and invasive medical procedures (1)
- sustainable energy source (1)
- symmetries (1)
- synthesis (1)
- synthetic MRI (1)
- system (1)
- tapered laser (1)
- tapers (1)
- targeted metabolite profiling (1)
- tau leptons (1)
- tautomerization (1)
- technological constraints (1)
- telecommunication spectral range (1)
- telescope (1)
- telluride (1)
- temperature (1)
- temporal bone (1)
- ternary organic solar cells (1)
- test facility (1)
- thermal barrier coating (1)
- thermal devices (1)
- thermal gating (1)
- thermal insulation (1)
- thermoelectric characterization (1)
- thermoelectric generator (1)
- thermoelectric generators (1)
- thin film (1)
- thin-film transistors (1)
- thorax (1)
- three terminal device (1)
- thulium telluride (1)
- time (1)
- time hole (1)
- time inhomogeneities (1)
- time resolved (1)
- time-of-flight mass spectrometry (1)
- time-resolved (1)
- time-resolved photoluminescence (1)
- timeresolved spectroscopy (1)
- tissue (1)
- tissue characterization (1)
- tomographic imaging method (1)
- tomography (1)
- top quark (1)
- top quark mass (1)
- top quarks (1)
- top-quark (1)
- top-quark mass (1)
- topological (1)
- topological analysis (1)
- topological magnetoelectric effect (1)
- topological materials (1)
- topological matter (1)
- topological superconductor (1)
- topological surface states (1)
- topological transitions (1)
- topologische Analyse (1)
- total energy (1)
- trARPES (1)
- transfer dynamics (1)
- transiente Absorption (1)
- transiente absorption spectroscopy (1)
- transition metal (1)
- transition metal dichalcogenide (1)
- transition metal oxides (1)
- transmission microscopy (1)
- transport gap (1)
- transport measurement (1)
- transport spectroscopy (1)
- transverse energy–energy correlation function (1)
- transverse relaxation (1)
- trap (1)
- trap distribution (1)
- trap states (1)
- trapped atoms/ions (1)
- triangular lattice (1)
- triplet excitons (1)
- triplets (1)
- tryptophan (1)
- tunable laser (1)
- tunnel contacts (1)
- tunneling diodes (1)
- twin suppression (1)
- two photon interference (1)
- two-dimensional electron gas (1)
- two-dimensional spectroscopy (1)
- two-photon absorption (1)
- type II GaIn(As)Sb/GaSb (1)
- type II quantum wells (1)
- ultra-short laser pulses (1)
- ultracold (1)
- ultrafast (1)
- ultrafast optics (1)
- ultrafast photonics (1)
- ultrafast spectroscopy (1)
- ultrakurz (1)
- ultraschnell (1)
- ultraschnelle Optik (1)
- ultrashort (1)
- ultraviolet photoelectron spectroscopy (1)
- undulation (1)
- up-conversion (1)
- vacancies (1)
- vacuum insulation panel (1)
- vapor-liquid-solid (1)
- variability (1)
- variable density sampling (1)
- vasa vasorum (1)
- vascular cell adhesion molecules (1)
- vascular surgery (1)
- vaskuläre Adhäsionsmoleküle (1)
- vector-field control (1)
- vector-field shaper (1)
- vector-like quarks (1)
- ventilation (1)
- verborgene Grenzflächen (1)
- verdünnte Nitride (1)
- vertebral artery (1)
- vertical (1)
- vertikal (1)
- vestibular aqueduct (VA) (1)
- vibronic electronic excitation (1)
- vicinal (1)
- video analysis (1)
- vis spectroscopy (1)
- water (1)
- water oxidation (1)
- water window (1)
- wavefront (1)
- waveguide (1)
- weak ferromagnetism (1)
- weit abstimmbare Laser (1)
- weite Abstimmbarkeit (1)
- well (1)
- wells (1)
- widely tunable laser (1)
- winkelaufgelöste Photoelektronenspektroskopie (1)
- wires (1)
- worm-like micelles (1)
- wässrige Lösung (1)
- x-ray absorption spectroscopy (1)
- x-ray diffraction (1)
- x-ray emission spectroscopy (1)
- x-ray imaging (1)
- x-ray inline phase contrast (1)
- x-ray magnetic circular dichroism (1)
- x-ray micro computed tomography (1)
- x-ray microscopy (1)
- x-ray spectroscopy (1)
- x-rays (1)
- xerogel (1)
- xylem cavitation (1)
- zeitafgelöst (1)
- zeitaufgelöste Spektroskopie (1)
- zone plate (1)
- zweidimensional (1)
- Übergangsmetalldichalkogenide (1)
- Überstruktur (1)
- √s=8 TeV (1)
Institute
- Physikalisches Institut (788) (remove)
Sonstige beteiligte Institutionen
- Wilhelm-Conrad-Röntgen-Forschungszentrum für komplexe Materialsysteme (4)
- Universitätsklinikum Würzburg (3)
- Röntgen Center for Complex Material Systems (RCCM), Am Hubland, 97074 W¨urzburg, Germany (2)
- ATLAS Collaboration (1)
- Arizona State University, Tempe, Arizona, USA (1)
- Bavarian Center for Applied Energy Research (ZAE Bayern), 97074 Würzburg, Germany (1)
- Bavarian Center for Applied Energy Research e.V. (ZAE Bayern) (1)
- Bayerisches Zentrum für Angewandte Energieforschung e.V. (1)
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut fuer biophysikalische Chemie (1)
- CERN (1)
ResearcherID
- D-1250-2010 (1)
- N-7500-2014 (1)
We present the optical characterization of GaAs-based InAs quantum dots (QDs) grown by molecular beam epitaxy on a digitally alloyed InGaAs metamorphic buffer layer (MBL) with gradual composition ensuring a redshift of the QD emission up to the second telecom window. Based on the photoluminescence (PL) measurements and numerical calculations, we analyzed the factors influencing the energies of optical transitions in QDs, among which the QD height seems to be dominating. In addition, polarization anisotropy of the QD emission was observed, which is a fingerprint of significant valence states mixing enhanced by the QD confinement potential asymmetry, driven by the decreased strain with increasing In content in the MBL. The barrier-related transitions were probed by photoreflectance, which combined with photoluminescence data and the PL temperature dependence, allowed for the determination of the carrier activation energies and the main channels of carrier loss, identified as the carrier escape to the MBL barrier. Eventually, the zero-dimensional character of the emission was confirmed by detecting the photoluminescence from single QDs with identified features of the confined neutral exciton and biexciton complexes via the excitation power and polarization dependences.
Exziton-Polaritonen (Polaritonen), hybride Quasiteilchen, die durch die starke Kopplung von Quantenfilm-Exzitonen mit Kavitätsphotonen entstehen, stellen auf Grund ihrer vielseitigen und kontrollierbaren Eigenschaften einen vielversprechenden Kandidaten für die Entwicklung einer neuen Generation von nichtlinearen und integrierten elektrooptischen Bauteilen dar. Die vorliegende Arbeit beschäftigt sich mit der Entwicklung und Untersuchung kompakter elektrooptischer Bauelemente auf der Basis von Exziton-Polaritonen in Halbleitermikrokavitäten.
Als erstes wird die Implementierung einer elektrisch angeregten, oberflächenemittierenden Polariton-Laserdiode vorgestellt, die ohne ein externes Magnetfeld arbeiten kann. Dafür wird der Schichtaufbau, der Q-Faktor, das Dotierprofil und die RabiAufspaltung der Polariton-Laserdiode optimiert. Der Q-Faktor des finalen Aufbaus beläuft sich auf Q ~ 16.000, während die Rabi-Aufspaltung im Bereich von ~ 11,0 meV liegt. Darauf aufbauend werden Signaturen der Polariton-Kondensation unter elektrischer Anregung, wie ein nichtlinearer Anstieg der Intensität, die Reduktion der Linienbreite und eine fortgesetzte Verschiebung der Emission zu höheren Energien oberhalb der ersten Schwelle, demonstriert. Ferner werden die Kohärenzeigenschaften des Polariton-Kondensats mittels Interferenzspektroskopie untersucht.
Basierend auf den optimierten Halbleiter-Mikroresonatoren wird eine Kontaktplattform für die elektrische Anregung ein- und zweidimensionaler Gitterstrukturen entwickelt. Dazu wird die Bandstrukturbildung eines Quadrat- und Graphen-Gitters unter elektrischer Anregung im linearen Regime untersucht und mit den Ergebnissen der optischen Charakterisierung verglichen. Die erhaltenen Dispersionen lassen sich durch das zugehörige Tight-Binding-Modell beschreiben. Ferner wird auch eine elektrisch induzierte Nichtlinearität in der Emission demonstriert. Die untersuchte Laser-Mode liegt auf der Höhe des unteren Flachbandes und an der Position der Γ-Punkte in der zweiten Brillouin-Zone. Die zugehörige Modenstruktur weist die erwartete Kagome-Symmetrie auf. Abschließend wird die Bandstrukturbildung eines SSH-Gitters mit eingebautem Defekt unter elektrischer Anregung untersucht und einige Eigenschaften des topologisch geschützten Defektzustandes gezeigt. Dazu gehört vor allem die Ausbildung der lokalisierten Defektmode in der Mitte der S-Bandlücke. Die erhaltenen Ergebnisse stellen einen wichtigen Schritt in der Realisierung eines elektrisch betriebenen topologischen Polariton-Lasers dar.
Abschließend wird ein elektrooptisches Bauteil auf der Basis von Polaritonen in einem Mikrodrahtresonator vorgestellt, in dem sich die Propagation eines PolaritonKondensats mittels eines elektrostatischen Feldes kontrollieren lässt. Das Funktionsprinzip des Polariton-Schalters beruht auf der Kombination einer elektrostatischen Potentialsenke unterhalb des Kontaktes und der damit verbundenen erhöhten ExzitonIonisationsrate. Der Schaltvorgang wird sowohl qualitativ als auch quantitativ analysiert und die Erhaltenen Ergebnisse durch die Modellierung des Systems über die GrossPitaevskii-Gleichung beschrieben. Zusätzlich wird ein negativer differentieller Widerstand und ein bistabiles Verhalten in der Strom-Spannungs-Charakteristik in Abhängigkeit von der Ladungsträgerdichte im Kontaktbereich beobachtet. Dieses Verhalten wird auf gegenseitig konkurrierende Kondensats-Zustände innerhalb der Potentialsenke und deren Besetzung und damit direkt auf den räumlichen Freiheitsgrad der PolaritonZustände zurückgeführt.
Masers as telecommunication amplifiers have been known for decades, yet their application is strongly limited due to extreme operating conditions requiring vacuum techniques and cryogenic temperatures. Recently, a new generation of masers has been invented based on optically pumped spin states in pentacene and diamond. In this study, we pave the way for masers based on spin S = 3/2 silicon vacancy (V\(_{Si}\)) defects in silicon carbide (SiC) to overcome the microwave generation threshold and discuss the advantages of this highly developed spin hosting material. To achieve population inversion, we optically pump the V\(_{Si}\) into their m\(_S\) = ±1/2 spin sub-states and additionally tune the Zeeman energy splitting by applying an external magnetic field. In this way, the prerequisites for stimulated emission by means of resonant microwaves in the 10 GHz range are fulfilled. On the way to realising a maser, we were able to systematically solve a series of subtasks that improved the underlying relevant physical parameters of the SiC samples. Among others, we investigated the pump efficiency as a function of the optical excitation wavelength and the angle between the magnetic field and the defect symmetry axis in order to boost the population inversion factor, a key figure of merit for the targeted microwave oscillator. Furthermore, we developed a high-Q sapphire microwave resonator (Q ≈ 10\(^4\)–10\(^5\)) with which we find superradiant stimulated microwave emission. In summary, SiC with optimized spin defect density and thus spin relaxation rates is well on its way of becoming a suitable maser gain material with wide-ranging applications.
In this work, a bridge was built between the so-far separate fields of spin defects and 2D systems: for the first time, an optically addressable spin defect (VB-) in a van der Waals material (hexagonal boron nitride) was identified and exploited. The results of this thesis are divided into three topics as follows:
1.) Identification of VB-:
In the scope of this chapter, the defect ,the negatively charged boron vacancy VB-, is identified and characterized. An initialization and readout of the spin state can be demonstrated optically at room temperature and its spin Hamiltonian contributions can be quantified.
2.) Coherent Control of VB-:
A coherent control is required for the defect to be utilized for quantum applications, which
Kavitäts-Exziton-Polaritonen (Polaritonen) sind hybride Quasiteilchen, die sich aufgrund starker Kopplung von Halbleiter-Exzitonen mit Kavitätsphotonen ausbilden. Diese Quasiteilchen weisen eine Reihe interessanter Eigenschaften auf, was sie einerseits für die Grundlagenforschung, andererseits auch für die Entwicklung neuartiger Bauteile sehr vielversprechend macht. Bei Erreichen einer ausreichend großen Teilchendichte geht das System in den Exziton-Polariton-Kondensationszustand über, was zur Emission von laserartigem Licht führt. Organische Halbleiter als aktives Emittermaterial zeigen in diesem Kontext großes Potential, da deren Exzitonen neben großen Oszillatorstärken auch hohe Bindungsenergien aufweisen. Deshalb ist es möglich, unter Verwendung organischer Halbleiter selbst bei Umgebungsbedingungen äußerst stabile Polaritonen zu erzeugen. Eine wichtige Voraussetzung zur Umsetzung von integrierten opto-elektronischen Bauteilen basierend auf Polaritonen ist der kontrollierte räumliche Einschluss sowie die Realisierung von frei konfigurierbaren Potentiallandschaften. Diese Arbeit beschäftigt sich mit der Entwicklung und der Untersuchung geeigneter Plattformen zur Erzeugung von Exziton-Polaritonen und Polaritonkondensaten in hemisphärischen Mikrokavitäten, in die organische Halbleiter eingebettet sind.
Charge transfer in ternary solar cells employing two fullerene derivatives: where do electrons go?
(2022)
Earlier reports demonstrated that ternary organic solar cells (OSC) made of donor polymers (D) blended with different mixtures of fullerene acceptors (A : A) performed very similarly. This finding is surprising, as the corresponding fullerene LUMO levels are slightly different, which might result in decisive differences in the charge transfer step. We investigate ternary OSC (D : A : A) made of the donor polymer P3HT with stoichiometric mixtures of different fullerene derivatives, PC\(_{60}\)BM : PC\(_{70}\)BM and PC\(_{70}\)BM : IC\(_{60}\)BA, respectively. Using quantitative electron paramagnetic resonance (EPR) we can distinguish between positive and negative polarons, localized on the specific molecules. We found that after the initial charge transfer step, the electrons are re-distributed over two nearby acceptors in agreement with their stoichiometry and their relative LUMO energy difference. Remarkably, the measured ΔLUMO differences in fullerene mixtures are reduced by an order of magnitude compared to that of the pristine materials, i. e., below 1 meV for PC\(_{60}\)BM : PC\(_{70}\)BM and (20±5) meV for PC\(_{70}\)BM : IC\(_{60}\)BA. Furthermore, we found that this reduced ΔLUMO explains the shift in open circuit voltage for D : A : A organic solar cells. We attribute these findings to hybridization, leading to an effective fullerene LUMO. Consequently, multi-acceptor blends are indeed a viable option for photodetectors and solar cells, as they combine the best electron acceptor and light absorbing properties.
Thermoplastic polymers have a history of decades of safe and effective use in the clinic as implantable medical devices. In recent years additive manufacturing (AM) saw increased clinical interest for the fabrication of customizable and implantable medical devices and training models using the patients’ own radiological data. However, approval from the various regulatory bodies remains a significant hurdle. A possible solution is to fabricate the AM scaffolds using materials and techniques with a clinical safety record, e.g. melt processing of polymers. Melt Electrowriting (MEW) is a novel, high resolution AM technique which uses thermoplastic polymers. MEW produces scaffolds with microscale fibers and precise fiber placement, allowing the control of the scaffold microarchitecture. Additionally, MEW can process medical-grade thermoplastic polymers, without the use of solvents paving the way for the production of medical devices for clinical applications. This pathway is investigated in this thesis, where the layout is designed to resemble the journey of a medical device produced via MEW from conception to early in vivo experiments. To do so, first, a brief history of the development of medical implants and the regenerative capability of the human body is given in Chapter 1. In Chapter 2, a review of the use of thermoplastic polymers in medicine, with a focus on poly(ε-caprolactone) (PCL), is illustrated, as this is the polymer used in the rest of the thesis. This review is followed by a comparison of the state of the art, regarding in vivo and clinical experiments, of three polymer melt AM technologies: melt-extrusion, selective laser sintering and MEW. The first two techniques already saw successful translation to the bedside, producing patient-specific, regulatory-approved AM implants. To follow in the footsteps of these two technologies, the MEW device parameters need to be optimized. The MEW process parameters and their interplay are further discussed in Chapter 3 focusing on the importance of a steady mass flow rate of the polymer during printing. MEW reaches a balance between polymer flow, the stabilizing electric field and moving collector to produce reproducible, high-resolution scaffolds. An imbalance creates phenomena like fiber pulsing or arcing which result in defective scaffolds and potential printer damage. Chapter 4 shows the use of X-ray microtomography (µCT) as a non-destructive method to characterize the pore-related features: total porosity and the pore size distribution. MEW scaffolds are three-dimensional (3D) constructs but have long been treated in the literature as two-dimensional (2D) ones and characterized mainly by microscopy, including stereo- and scanning electron microscopy, where pore size was simply reported as the distance between the fibers in a single layer. These methods, together with the trend of producing scaffolds with symmetrical pores in the 0/90° and 0/60/120° laydown patterns, disregarded the lateral connections between pores and the potential of MEW to be used for more complex 3D structures, mimicking the extracellular matrix. Here we characterized scaffolds in the aforementioned symmetrical laydown patterns, along with the more complex 0/45/90/135° and 0/30/60/90/120/150° ones. A 2D pore size estimation was done first using stereomicroscopy, followed by and compared to µCT scanning. The scaffolds with symmetrical laydown patterns resulted in the predominance of one pore size, while those with more complex patterns had a broader distribution, which could be better shown by µCT scans. Moreover, in the symmetrical scaffolds, the size of 3D pores was not able to reach the value of the fiber spacing due to a flattening effect of the scaffold, where the thickness of the scaffold was less than the fiber spacing, further restricting the pore size distribution in such scaffolds. This method could be used for quality assurance of fabricated scaffolds prior to use in in vitro or in vivo experiments and would be important for a clinical translation. Chapter 5 illustrates a proof of principle subcutaneous implantation in vivo experiment. MEW scaffolds were already featured in small animal in vivo experiments, but to date, no analysis of the foreign body reaction (FBR) to such implants was performed. FBR is an immune reaction to implanted foreign materials, including medical devices, aimed at protecting the host from potential adverse effects and can interfere with the function of some medical implants. Medical-grade PCL was used to melt electrowrite scaffolds with 50 and 60 µm fiber spacing for the 0/90° and 0/60/120° laydown patterns, respectively. These implants were implanted subcutaneously in immunocompetent, outbred mice, with appropriate controls, and explanted after 2, 4, 7 and 14 days. A thorough characterization of the scaffolds before implantation was done, followed by a full histopathological analysis of the FBR to the implants after excision. The scaffolds, irrespective of their pore geometry, induced an extensive FBR in the form of accumulation of foreign body giant cells around the fiber walls, in a manner that almost occluded available pore spaces with little to no neovascularization. This reaction was not induced by the material itself, as the same reaction failed to develop in the PCL solid film controls. A discussion of the results was given with special regard to the literature available on flat surgical meshes, as well as other hydrogel-based porous scaffolds with similar pore sizes. Finally, a general summary of the thesis in Chapter 6 recapitulates the most important points with a focus on future directions for MEW.
Point-spread function engineering for single-molecule localization microscopy in brain slices
(2022)
Single-molecule localization microscopy (SMLM) is the method of choice to study biological specimens on a nanoscale level. Advantages of SMLM imply its superior specificity due to targeted molecular fluorescence labeling and its enhanced tissue preservation compared to electron microscopy, while reaching similar resolution. To reveal the molecular organization of protein structures in brain tissue, SMLM moves to the forefront: Instead of investigating brain slices with a thickness of a few µm, measurements of intact neuronal assemblies (up to 100 µm in each dimension) are required. As proteins are distributed in the whole brain volume and can move along synapses in all directions, this method is promising in revealing arrangements of neuronal protein markers. However, diffraction-limited imaging still required for the localization of the fluorophores is prevented by sample-induced distortion of emission pattern due to optical aberrations in tissue slices from non-superficial planes. In particular, the sample causes wavefront dephasing, which can be described as a summation of Zernike polynomials. To recover an optimal point spread function (PSF), active shaping can be performed by the use of adaptive optics. The aim of this thesis is to establish a setup using a deformable mirror and a wavefront sensor to actively shape the PSF to correct the wavefront phases in a super-resolution microscope setup. Therefore, fluorescence-labeled proteins expressed in different anatomical regions in brain tissue will be used as experiment specimen. Resolution independent imaging depth in slices reaching tens of micrometers is aimed.
Improved radiological examinations with newly developed 3D models may increase understanding of Meniere's disease (MD). The morphology and course of the vestibular aqueduct (VA) in the temporal bone might be related to the severity of MD. The presented study explored, if the VA of MD and non-MD patients can be grouped relative to its angle to the semicircular canals (SCC) and length using a 3D model. Scans of temporal bone specimens (TBS) were performed using micro-CT and micro flat panel volume computed tomography (mfpVCT). Furthermore, scans were carried out in patients and TBS by computed tomography (CT). The angle between the VA and the three SCC, as well as the length of the VA were measured. From these data, a 3D model was constructed to develop the vestibular aqueduct score (VAS). Using different imaging modalities it was demonstrated that angle measurements of the VA are reliable and can be effectively used for detailed diagnostic investigation. To test the clinical relevance, the VAS was applied on MD and on non-MD patients. Length and angle values from MD patients differed from non-MD patients. In MD patients, significantly higher numbers of VAs could be assigned to a distinct group of the VAS. In addition, it was tested, whether the outcome of a treatment option for MD can be correlated to the VAS.
In this study we characterize the tautomerization of HPc on Cu(111) as a charge-carrier-induced reversible one-electron process. An analysis of the bias-dependent tautomerization rate finds an energy threshold that corresponds to the energy of the N-H stretching mode. By using the tautomerization of the molecule as a detector for charge carrier transport in the so-called molecular nanoprobe (MONA) technique, we provide evidence for an inhomogeneous coupling between the fourfold-symmetric molecule and sixfold-symmetric surface. We conclude the study by comparing the energy dependence of charge carrier transport on the Cu(111) to the Ag(111) surface. While the MONA technique is limited to the detection of hot-electron transport for Ag(111), our data reveal that the lower onset energy of the Cu surface state also allows for the detection of hot-hole transport. The influence of surface and bulk transport on the MONA technique is discussed.
This work investigates the correlations between spin states and the light emission properties of organic light-emitting diodes (OLEDs), which are based on the principle of thermally activated delayed fluorescence. The spin-spin interactions responsible for this mechanism are investigated in this work using methods based on spin-sensitive electron paramagnetic resonance (EPR). In particular, this method has been applied to electrically driven OLEDs. The magnetic resonance has been detected by electroluminescence, giving this method its name: electroluminescence detected magnetic resonance (ELDMR).
Initial investigations on a novel deep blue TADF emitter were performed. Furthermore, the ELDMR method was used in this work to directly detect the spin states in the OLED. These measurements were further underlined by time-resolved experiments such as transient electro- and photoluminescence.
Laser spectroscopic gas sensing has been applied for decades for several applications
as atmospheric monitoring, industrial combustion gas analysis or fundamental research.
The availability of new laser sources in the mid-infrared opens the spectral fingerprint
range to the technology where multiple molecules possess their fundamental ro-vibrational
absorption features that allow very sensitive detection and accurate discrimination of
the species. The increasing maturity of quantum cascade lasers that cover this highly
interesting spectral range motivated this research to gain fundamental knowledge about
the spectra of hydrocarbon gases in pure composition and in complex mixtures as they
occur in the petro-chemical industry. The long-term target of developing accurate and fast
hydrocarbon gas analyzers, capable of real-time operation while enabling feedback-loops,
would lead to a paradigm change in this industry.
This thesis aims to contribute to a higher accuracy and more comprehensive understanding
of the sensing of hydrocarbon gas mixtures. This includes the acquisition of yet
unavailable high resolution and high accuracy reference spectra of the respective gases,
the investigation of their spectral behavior in mixtures due to collisional broadening of
their transitions and the verification of the feasibility to quantitatively discriminate the
spectra when several overlapping species are simultaneously measured in gas mixtures.
To achieve this knowledge a new laboratory environment was planned and built up to
allow for the supply of the individual gases and their arbitrary mixing. The main element
was the development of a broadly tunable external-cavity quantum cascade laser based
spectrometer to record the required spectra. This also included the development of a new
measurement method to obtain highly resolved and nearly gap-less spectral coverage as
well as a sophisticated signal post-processing that was crucial to achieve the high accuracy
of the measurements. The spectroscopic setup was used for a thorough investigation of
the spectra of the first seven alkanes as of their mixtures. Measurements were realized
that achieved a spectral resolution of 0.001 cm-1 in the range of 6-11 µm while ensuring an
accuracy of 0.001 cm-1 of the spectra and attaining a transmission sensitivity of 2.5 x 10-4
for long-time averaging of the acquired spectra.
These spectral measurements accomplish a quality that compares to state-of-the art
spectral databases and revealed so far undocumented details of several of the investigated
gases that have not been measured with this high resolution before at the chosen measurement
conditions. The results demonstrate the first laser spectroscopic discrimination of a
seven component gas mixture with absolute accuracies below 0.5 vol.% in the mid-infrared
provided that a sufficiently broad spectral range is covered in the measurements. Remaining
challenges for obtaining improved spectral models of the gases and limitations of the
measurement accuracy and technology are discussed.
Novel appraches to the molecular beam epitaxy of core-shell nanowires in the group II telluride material system were explored in this work. Significant advances in growth spurred the development of a flexible and reliable platform for a charge transport characterization of the topological insulator HgTe in a tubular nanowire geometry. The transport results presented provide an important basis for the design of future studies that strive for the experimental realization of topological charge transport in the quantum wire limit.
Optical quantum information science and technologies require the capability to generate, control, and detect single or multiple quanta of light. The need to detect individual photons has motivated the development of a variety of novel and refined single-photon detectors (SPDs) with enhanced detector performance. Superconducting nanowire single-photon detectors (SNSPDs) and single-photon avalanche diodes (SPADs) are the top-performer in this field, but alternative promising and innovative devices are emerging. In this review article, we discuss the current state-of-the-art of one such alternative device capable of single-photon counting: the resonant tunneling diode (RTD) single-photon detector. Due to their peculiar photodetection mechanism and current-voltage characteristic with a region of negative differential conductance, RTD single-photon detectors provide, theoretically, several advantages over conventional SPDs, such as an inherently deadtime-free photon-number resolution at elevated temperatures, while offering low dark counts, a low timing jitter, and multiple photon detection modes. This review article brings together our previous studies and current experimental results. We focus on the current limitations of RTD-SPDs and provide detailed design and parameter variations to be potentially employed in next-generation RTD-SPD to improve the figure of merits of these alternative single-photon counting devices. The single-photon detection capability of RTDs without quantum dots is shown.
Magnetic nanoparticles (MNPs) have been adapted for many applications, e.g., bioassays for the detection of biomarkers such as antibodies, by controlled engineering of specific surface properties. Specific measurement of such binding states is of high interest but currently limited to highly sensitive techniques such as ELISA or flow cytometry, which are relatively inflexible, difficult to handle, expensive and time-consuming. Here we report a method named COMPASS (Critical-Offset-Magnetic-Particle-SpectroScopy), which is based on a critical offset magnetic field, enabling sensitive detection to minimal changes in mobility of MNP ensembles, e.g., resulting from SARS-CoV-2 antibodies binding to the S antigen on the surface of functionalized MNPs. With a sensitivity of 0.33 fmole/50 µl (≙7 pM) for SARS-CoV-2-S1 antibodies, measured with a low-cost portable COMPASS device, the proposed technique is competitive with respect to sensitivity while providing flexibility, robustness, and a measurement time of seconds per sample. In addition, initial results with blood serum demonstrate high specificity.
Effective lifting of the topological protection of quantum spin Hall edge states by edge coupling
(2022)
The scientific interest in two-dimensional topological insulators (2D TIs) is currently shifting from a more fundamental perspective to the exploration and design of novel functionalities. Key concepts for the use of 2D TIs in spintronics are based on the topological protection and spin-momentum locking of their helical edge states. In this study we present experimental evidence that topological protection can be (partially) lifted by pairwise coupling of 2D TI edges in close proximity. Using direct wave function mapping via scanning tunneling microscopy/spectroscopy (STM/STS) we compare isolated and coupled topological edges in the 2D TI bismuthene. The latter situation is realized by natural lattice line defects and reveals distinct quasi-particle interference (QPI) patterns, identified as electronic Fabry-Pérot resonator modes. In contrast, free edges show no sign of any single-particle backscattering. These results pave the way for novel device concepts based on active control of topological protection through inter-edge hybridization for, e.g., electronic Fabry-Pérot interferometry.
The future of water-derived hydrogen as the “sustainable energy source” straightaway bets on the success of the sluggish oxygen-generating half-reaction. The endeavor to emulate the natural photosystem II for efficient water oxidation has been extended across the spectrum of organic and inorganic combinations. However, the achievement has so far been restricted to homogeneous catalysts rather than their pristine heterogeneous forms. The poor structural understanding and control over the mechanistic pathway often impede the overall development. Herein, we have synthesized a highly crystalline covalent organic framework (COF) for chemical and photochemical water oxidation. The interpenetrated structure assures the catalyst stability, as the catalyst’s performance remains unaltered after several cycles. This COF exhibits the highest ever accomplished catalytic activity for such an organometallic crystalline solid-state material where the rate of oxygen evolution is as high as ∼26,000 μmol L\(^{–1}\) s\(^{–1}\) (second-order rate constant k ≈ 1650 μmol L s\(^{–1}\) g\(^{–2}\)). The catalyst also proves its exceptional activity (k ≈ 1600 μmol L s\(^{–1}\) g\(^{–2}\)) during light-driven water oxidation under very dilute conditions. The cooperative interaction between metal centers in the crystalline network offers 20–30-fold superior activity during chemical as well as photocatalytic water oxidation as compared to its amorphous polymeric counterpart.
Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the 2–4 μm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor's electrical response and how they allow controlling the device's sensing abilities.
Thin films of transition metal oxides open up a gateway to nanoscale electronic devices beyond silicon characterized by novel electronic functionalities. While such films are commonly prepared in an oxygen atmosphere, they are typically considered to be ideally terminated with the stoichiometric composition. Using the prototypical correlated metal SrVO\(_{3}\) as an example, it is demonstrated that this idealized description overlooks an essential ingredient: oxygen adsorbing at the surface apical sites. The oxygen adatoms, which are present even if the films are kept in an ultrahigh vacuum environment and not explicitly exposed to air, are shown to severely affect the intrinsic electronic structure of a transition metal oxide film. Their presence leads to the formation of an electronically dead surface layer but also alters the band filling and the electron correlations in the thin films. These findings highlight that it is important to take into account surface apical oxygen or—mutatis mutandis—the specific oxygen configuration imposed by a capping layer to predict the behavior of ultrathin films of transition metal oxides near the single unit-cell limit.
Thermoelectric materials utilizing ionic transport open-up entirely new possibilities for the recuperation of waste heat. Remarkably, solid state electrolytes which have entered the focus of battery research in recent years turn-out to be promising candidates also for ionic thermoelectrics. Here, the dynamics of ionic transport and thermoelectric properties of a methacrylate based polymer blend in combination with a lithium salt is analyzed. Impedance spectroscopy data indicates the presence of just one transport mechanism irrespective of lithium salt concentration. In contrast, the temperature dependent ionic conductivity increases with salt concentration and can be ascribed to a Vogel–Fulcher–Tammann (VFT) behavior. The obtained Seebeck coefficients of 2 mV K\(^{−1}\) allow for high power outputs while the polymer matrix maintains the temperature gradient by its low thermal conductivity. Adding multi-walled carbon nanotubes to the polymer matrix allows for variation of the Seebeck coefficient as well as the ionic and electronic conductivities. As a result, a transition between a high temperature VFT regime and a low temperature Arrhenius regime appears at a critical temperature, T\(_{c}\), shifting upon addition of salt. The observed polarity change in Seebeck voltage at T\(_{c}\) suggests a new mode of thermoelectric operation, which is demonstrated by a proof-of-concept mixed electronic-ionic-thermoelectric generator.
Excitons in atomically thin transition-metal dichalcogenides (TMDs) have been established as an attractive platform to explore polaritonic physics, owing to their enormous binding energies and giant oscillator strength. Basic spectral features of exciton polaritons in TMD microcavities, thus far, were conventionally explained via two-coupled-oscillator models. This ignores, however, the impact of phonons on the polariton energy structure. Here we establish and quantify the threefold coupling between excitons, cavity photons, and phonons. For this purpose, we employ energy-momentum-resolved photoluminescence and spatially resolved coherent two-dimensional spectroscopy to investigate the spectral properties of a high-quality-factor microcavity with an embedded WSe\(_2\) van-der-Waals heterostructure at room temperature. Our approach reveals a rich multi-branch structure which thus far has not been captured in previous experiments. Simulation of the data reveals hybridized exciton-photon-phonon states, providing new physical insight into the exciton polariton system based on layered TMDs.
In this work the creation of silicon vacancy spin defects in silicon carbide with predictable properties is demonstrated. Neutron and electron irradiation was used to create silicon vacancy ensembles and proton beam writing to create isolated vacancies at a desired position. The coherence properties of the created silicon vacancies as a function of the emitter density were investigated and a power-law function established. Sample annealing was implemented to increase the coherence properties of existing silicon vacancies. Further, spectral hole burning was used to implement absolute dc-magnetometry.
Stationäre Gasturbinen können von großer Bedeutung für die Verlangsamung des Klima-wandels und bei der Bewältigung der Energiewende sein. Für die Weiterentwicklung von Gasturbinen zu höheren Betriebstemperaturen und damit einhergehend zu höheren Wirkungs-graden werden berührungslose Messverfahren zur Ermittlung der Oberflächentemperatur von Turbinenschaufeln und der Gastemperatur der heißen Verbrennungsgase während des Be-triebs benötigt. Im Rahmen dieser Arbeit werden daher Methoden der berührungslosen Tem-peraturmessung unter Verwendung von Infrarotstrahlung untersucht.
Die berührungslose Messung der Oberflächentemperatur moderner Turbinenschaufeln muss aufgrund derer infrarot-optischer Oberflächeneigenschaften im Wellenlängenbereich des mitt-leren Infrarots durchgeführt werden, in welchem die Turbinenbrenngase starke Absorptions-banden aufweisen. Zur Entwicklung eines adäquaten Strahlungsthermometers für diesen Zweck wurden im Rahmen dieser Arbeit daher durch Ermittlung von Transmissionsspektren von Kohlenstoffdioxid und Wasserdampf bei hohen Temperaturen und Drücken in einer ei-gens hierfür konstruierten Heißgas-Messzelle zunächst Wellenlängenbereiche identifiziert, in welchen die geplanten Messungen möglich sind. Anschließend wurde der Prototyp eines ent-sprechend konfigurierten Strahlungsthermometers im Zuge des Testlaufes einer vollskaligen Gasturbine erfolgreich erprobt.
Weiterhin wurden im Rahmen dieser Arbeit zwei mögliche Verfahren zur berührungslosen Gastemperaturmessung untersucht. Das erste untersuchte Verfahren setzt ebenfalls auf Strah-lungsthermometrie. Dieses Verfahren sieht vor, aufgrund der Temperaturabhängigkeit des spektralen Transmissionsgrades in den Randbereichen von gesättigten Absorptionsbanden von Gasen aus der in diesen Bereichen transmittierten spektralen Strahldichte auf die Gastempera-tur zu schließen. Im Rahmen dieser Arbeit wurden Voruntersuchungen für dieses Tempera-turmessverfahren durchgeführt. So konnten auf der Grundlage von experimentell ermittelten Transmissionsspektren von Kohlenstoffdioxid bei Drücken zwischen 5 kPa und 600 kPa und Gastemperaturen zwischen Raumtemperatur und 1073 K für das geplante Verfahren nutzbare Wellenlängenintervalle insbesondere im Bereich der Kohlenstoffdioxid-Bande bei 4,26 µm identifiziert werden.
Das zweite im Rahmen dieser Arbeit untersuchte Verfahren zur berührungslosen Gastem-peraturmessung basiert auf der Temperaturabhängigkeit der Wellenlängenposition der Trans-missionsminima der Absorptionsbanden von infrarot-aktiven Gasen. Im Hinblick darauf wur-de dieses Phänomen anhand von experimentell bestimmten hochaufgelösten Transmissions-spektren von Kohlenstoffdioxid überprüft. Weiterhin wurden mögliche Wellenlängenbereiche identifiziert und hinsichtlich ihrer Eignung für das geplante Verfahren charakterisiert. Als am vielversprechendsten erwiesen sich hierbei Teilbanden in den Bereichen um 2,7 µm und um 9,2 µm. Unter Beimischung von Stickstoff mit Partialdrücken von bis zu 390 kPa erwies sich zudem auch die Bande bei 4,26 µm als geeignet.
Die im Rahmen dieser Arbeit experimentell ermittelten Transmissionsspektren konnten dar-über hinaus schließlich durch Vergleich mit entsprechenden HITRAN-Simulationen verifiziert werden.
This thesis focused on the influence of the underlying crystal structure and hence, of the mutual molecular orientation, on the excited states in ordered molecular aggregates. For this purpose, two model systems have been investigated. In the prototypical donor-acceptor complex pentacene-perfluoropentacene (PEN-PFP) the optical accessibility of the charge transfer state and the possibility to fabricate highly defined interfaces by means of single crystal templates enabled a deep understanding of the spatial anisotropy of the charge transfer state formation. Transferring the obtained insights to the design of prototypical donor-acceptor devices, the importance of interface control to minimize the occurrence of charge transfer traps and thereby, to improve the device performance, could be demonstrated. The use of zinc phthalocyanine (ZnPc) allowed for the examination of the influence of molecular packing on the excited electronic states without a change in molecular species by virtue of its inherent polymorphism. Combining structural investigations, optical absorption and emission spectroscopy, as well as Franck-Condon modeling of emission spectra revealed the nature of the optical excited state emission in relation to the structural \(\alpha \) and \(\beta \) phase over a wide temperature range from 4 K to 300 K. As a results, the phase transition kinetics of the first order \(\alpha \rightarrow \beta\) phase transition were characterized in depth and applied to the fabrication of prototypical dual luminescent OLEDs.
Spin-Orbit Torques and Galvanomagnetic Effects Generated by the 3D Topological Insulator HgTe
(2021)
Nature shows us only the tail of the lion. But I have no doubt that the lion belongs with it even if he cannot reveal himself all at once. Albert Einstein
In my dissertation, I addressed the question of whether the 3D topological insulator mercury telluride (3D TI HgTe) is a suitable material for spintronics applications. This question was addressed by investigating the SOTs generated by the 3D TI HgTe in an adjacent ferromagnet (Permalloy) by using the ferromagnetic resonance technique (SOT-FMR).
In the first part of the dissertation, the reader was introduced to the mathematical description of the SOTs of a hybrid system consisting of a topological insulator (TI) and a ferromagnet (FM). Furthermore, the sample preparation and the measurement setup for the SOT-FMR measurements were discussed. Our SOT-FMR measurements showed that at low temperatures (T = 4.2 K) the out-of-plane component of the torque is dominant. At room temperature, both in-plane and out-of-plane components of the torque could be observed. From the symmetry of the mixing voltage (Figs. 3.14 and 3.15) we could conclude that the 3D TI HgTe may be efficient for the generation of spin torques in the permalloy [1]. The investigations reported here showed that the SOT efficiencies generated by the 3D TI HgTe are comparable with other existent topological insulators (see Fig. 3.17). We also discussed in detail the parasitic effects (such as thermovoltages) that can contribute to the correct interpretation of the spin torque efficiencies.
Although the results reported here provide several indications that the 3D TI HgTe might be efficient in exerting spin-torques in adjacent ferromagnets [2], the reader was repeatedly made aware that parasitic effects might contaminate the correct writing and reading of the information in the ferromagnet. These effects should be taken into consideration when interpreting results in the published literature claiming high spin-orbit torque efficiencies [2–4]. The drawbacks of the SOT-FMR measurement method led to a further development of our measurement concept, in which the ferromagnet on top of the 3D TI HgTe was replaced by a
spin-valve structure. In contrast with our measurements, in this measurement setup, the current flowing through the HgTe is known and changes in the spin-valve resistance can be read via the GMR effect.
Moreover, the SOT-FMR experiments required the application of an in-plane magnetic field up to 300 mT to define the magnetization direction in the ferromagnet. Motivated by this fact, we investigated the influence of an in-plane magnetic field in the magnetoresistance of the 3D TI HgTe. The surprising results of these measurements are described in the second part of the dissertation. Although the TI studied here is non-magnetic, its transversal MR (Rxy) showed an oscillating behavior that depended on the angle between the in-plane magnetic field and the electrical current. This effect is a typical property of ferromagnetic materials and is called planar Hall effect (PHE) [5, 6]. Moreover, it was also shown that the PHE amplitude (Rxy) and the longitudinal resistance (Rxx) oscillate as a function of the in-plane magnetic field amplitude for a wide range of carrier densities of the topological insulator.
The PHE was already described in another TI material (Bi2−xSbxTe3) [7]. The authors suggested as a possible mechanism the scattering of the electron off impurities that are polarized by an in-plane magnetic field. We critically discussed this and other theoretical proposed mechanisms existent in the literature [8, 9].
In this thesis, we attempted to explain the origin of the PHE in the 3D TI HgTe by anisotropies in the band structure of this material. The k.p calculations based on 6-orbitals were able to demonstrate that an interplay between Rashba, Dresselhaus, and in-plane magnetic field deforms the Fermi contours of the camel back band of the 3D TI HgTe, which could lead to anisotropies in its conductivity. However, the magnetic fields needed to experimentally observe this effect are as
high as 40 T, i.e., one order of magnitude higher than reported in our experiments. Additionally, calculations of the DoS to assess if there is a difference in the states for Bin parallel and Bin perpendicular to the current were, so far, inconclusive. Moreover, the complicated dependence of Rashba in the p-conducting
regime of HgTe [10] makes it not straightforward the inclusion of this term in the band structure calculations.
Despite the extensive efforts to understand the origin of the galvanomagnetic effects in the 3D TI HgTe, we could not determine a clear mechanism for the origin of the PHE and the MR oscillations studied in this thesis. However, our work clarifies and excludes a few mechanisms reported in the literature as the origin of these effects in the 3D TI HgTe. The major challenge, which still needs to be overcome, is to find a model that simultaneously explains the PHE, the gate dependence, and the oscillations in the magnetoresistance of the 3D TI HgTe as a function of the in-plane magnetic field.
To conclude, the author would like to express her hope to have brought the reader closer to the complexity of the questions addressed in this thesis and to have initiated them into the art of properly conducting electrical transport measurements on topological insulators with in-plane magnetic fields.
X-ray full-field microscopy at laboratory sources for photon energies above 10 keV suffers from either long exposure times or low resolution. The photon flux is mainly limited by the objectives used, having a limited numerical aperture NA. We show that this can be overcome by making use of the cone-beam illumination of laboratory sources by imaging the same field of view (FoV) several times under slightly different angles using an array of X-ray lenses. Using this technique, the exposure time can be reduced drastically without any loss in terms of resolution. A proof-of-principle is given using an existing laboratory metal-jet source at the 9.25 keV Ga K\(_α\)-line and compared to a ray-tracing simulation of the setup.
The SNR spectra model and measurement method developed in this work yield reliable application-specific optima for image quality. This optimization can either be used to understand image quality, find out how to build a good imaging device or to (automatically) optimize the parameters of an existing setup.
SNR spectra are here defined as a fraction of power spectra instead of a product of device properties. In combination with the newly developed measurement method for this definition, a close correspondence be- tween theory and measurement is achieved. Prior approaches suffer from a focus on theoretical definitions without fully considering if the defined quantities can be measured correctly. Additionally, discrepancies between assumptions and reality are common.
The new approach is more reliable and complete, but also more difficult to evaluate and interpret. The signal power spectrum in the numerator of this fraction allows to model the image quality of different contrast mechanisms that are used in high-resolution x-ray imaging. Superposition equations derived for signal and noise enable understanding how polychromaticity (or superposition in general) affects the image quality.
For the concept of detection energy weighting, a quantitative model for how it affects im- age quality was found. It was shown that—depending on sample properties—not detecting x-ray photons can increase image quality. For optimal computational energy weighting, more general formula for the optimal weight was found. In addition to the signal strength, it includes noise and modulation transfer.
The novel method for measuring SNR spectra makes it possible to experimentally optimize image quality for different contrast mechanisms. This method uses one simple measurement to obtain a measure for im- age quality for a specific experimental setup. Comparable measurement methods typically require at least three more complex measurements, where the combination may then give a false result. SNR spectra measurements can be used to:
• Test theoretical predictions about image quality optima.
• Optimize image quality for a specific application.
• Find new mechanisms to improve image quality.
The last item reveals an important limitation of x- ray imaging in general: The achievable image quality is limited by the amount of x-ray photons interacting with the sample, not by the amount incident per detector area (see section 3.6). If the rest of the imaging geometry is fixed, moving the detector only changes the field of view, not the image quality. A practical consequence is that moving the sample closer to the x-ray source increases image quality quadratically.
The results of a SNR spectra measurement represent the image quality only on a relative scale, but very reliable. This relative scale is sufficient for an optimization problem. Physical effects are often already clearly identifiable by the shape of the functional relationship between input parameter and measurement result.
SNR spectra as a quantity are not well suited for standardization, but instead allow a reliable optimization. Not satisfying the requirements of standardization allows to use methods which have other advantages. In this case, the SNR spectra method describes the image quality for a specific application. Consequently, additional physical effects can be taken into account. Additionally, the measurement method can be used to automate the setting of optimal machine parameters.
The newly proposed image quality measure detection effectiveness is better suited for standardization or setup comparison. This quantity is very similar to measures from other publications (e.g. CNR(u)), when interpreted monochromatically. Polychromatic effects can only be modeled fully by the DE(u). The measurement processes of both are different and the DE(u) is fundamentally more reliable.
Information technology and digital data processing make it possible to determine SNR spectra from a mea- sured image series. This measurement process was designed from the ground up to use these technical capabilities. Often, information technology is only used to make processes easier and more exact. Here, the whole measurement method would be infeasible without it. As this example shows, using the capabilities of digital data processing much more extensively opens many new possibilities. Information technology can be used to extract information from measured data in ways that analog data processing simply cannot.
The original purpose of the SNR spectra optimization theory and methods was to optimize high resolution x-ray imaging only. During the course of this work, it has become clear that some of the results of this work affect x-ray imaging in general. In the future, these results could be applied to MI and NDT x-ray imaging. Future work on the same topic will also need to consider the relationship between SNR spectra or DE(u) and sufficient image quality.This question is about the minimal image quality required for a specific measurement task.
Ziel dieser Arbeit war die Stabilisierung von Cadmiumsulfid CdS mit Pluronic P123, einem Polymer.
CdS ist ein Halbleiter, der zum Beispiel in der Photonik und bei optischen Anwendungen eingesetzt wird und ist deshalb äußerst interessant, da seine Bandlücke als Nanopartikel verschiebbar ist. Für die Photovoltaik ist es ein attraktives Material, da es im sichtbaren Licht absorbiert und durch die Bandlückenverschiebung effektiver absorbieren kann. Dies ist unter dem Namen Quantum Size Effekt bekannt. Als Feststoff ist CdS für einen solchen Anwendungsbereich weniger geeignet, zumal der Effekt der Bandlückenverschiebung dort nicht auftritt. Wissenschaftler bemühen sich deshalb CdS als Nanopartikeln zu stabilisieren, weil CdS in wässrigen Lösungen ein stark aggregierendes System, also stark hydrophob ist. Es wurden zwei Kriterien für die erfolgreiche Stabilisierung von CdS festgelegt. Zum einen muss das Cds homogen im Medium verteilt sein und darf nicht agglomerieren. Zum anderen, müssen die CdS Nanopartikel kleiner als 100 A sein.
In meiner Arbeit habe ich solche Partikel hergestellt und stabilisiert, d.h. verhindert, dass die Partikel weiterwachsen und gleichzeitig ihre Bandlücke verschoben wird. Die Herausforderung liegt nicht in der Herstellung, aber in der Lösung von CdS im Trägerstoff, da CdS in den meisten Flüssigkeiten nicht löslich ist und ausfällt. Die Stabilisierung in wässrigen Lösungen wurde das erste Mal durch Herrn Prof. Dr. Rempel mit Ethylendiamintetraessigsäure EDTA erfolgreich durchgeführt. Mit EDTA können jedoch nur sehr kleine Konzentrationen stabilisiert werden. Zudem können Parameter wie Größe und Geschwindigkeit der Reaktion beim Stabilisieren der CdS-Nanopartikel nicht angepasst oder beeinflusst werden. Dieses Problem ist dem, vieler medizinischer Wirkstoffe sehr ähnlich, die in hohen Konzentrationen verabreicht werden sollen, aber nicht oder nur schwer in Wasser löslich sind (Bsp. Kurkumin). Ein vielversprechender Lösungsweg ist dort, die Wirkstoffe in große Trägerpartikel (sog. Mizellen) einzuschleusen, die ihrerseits gut löslich sind. In meiner Arbeit habe ich genau diesen Ansatz für CdS verfolgt. Als Trägerpartikel/Mizelle wurde das bekannte Copolymer Pluronic P123 verwendet. Aus dieser Pluronic Produktreihe wird P123 gewählt, da es die größte Masse bei gleichzeitig höchstem Anteil von Polypropylenoxid PPO im Vergleich zur Gesamtkettenlänge hat. P123 ist ein ternäres Polyether oder Dreiblockkopolymer und wird von BASAF industriell produziert. Es besteht aus drei Böcken, dem mittlere Block Polypropylenoxid PPO und den beiden äußeren Blöcken Polyethylenoxid PEO. Der Buchstabe P steht für pastös, die ersten beiden Ziffern in P123 mit 300 multipliziert ergeben das molare Gewicht und die letzte Ziffer mit 10 multipliziert entspricht dem prozentualen Gewichtsanteil PEO. Die Bildung von Mizellen aus den P123 Molekülen kann bewusst über geringe Temperaturänderungen gesteuert werden. Bei ungefähr Raumtemperatur liegen Mizellen vor, die sich bei höheren Temperaturen von sphärischen in wurmartige Mizellen umwandeln. Oberhalb einer Konzentration von 30 Gewichtsprozent wtp bilden die Mizellen außerdem einen Flüssigkristall. Ich habe in meiner Arbeit zunächst P123 mit Hilfe von Röntgenstreuung untersucht. Anders als andere Methoden gibt Röntgenstreuung direkten Aufschluss über die Morphologie der Stoffe. Röntgenstreuung kann die Mischung von P123 mit CdS abbilden und lässt darauf schließen, ob das Ziel erreicht werden konnte, stabile CdS Nanopartikel in P123 zu binden.
Für die Stabilisierung der Nanopartikel ist es zunächst notwendig die richtigen Temperaturen für die Ausgangslösungen und gemischten Lösungen zu finden. Dazu muss P123 viel genauer untersucht werden, als der momentane Kenntnisstand in der Literatur. Zu diesem Zweck als auch für die Analyse des stabilisierten CdS habe ich ein neues Instrument am LRM entwickelt, sowie eine temperierbare Probenumgebung für Flüssigkeiten fürs Vakuum, um morphologische Eigenschaften aus Streuamplituden und -winkeln zu entschlüsseln. Diese Röntgenstreuanlage wurde konzipiert und gebaut, um auch im Labor P123 in kleinen Konzentrationen messen zu können. Röntgenkleinwinkelstreuung eignet sich besonders als Messmethode, da die Probe mit einer hohen statistischen Relevanz in Flüssigkeit und in verschiedenen Konzentrationen analysiert werden kann.
Für die Konzentrationen 5, 10 und 30 wtp konnte das temperaturabhängige Verhalten von P123 präzise mit Röntgenkleinwinkelstreuung SAXS gemessen und dargestellt werden. Für 5 wtp konnten die Größen der Unimere und Mizellen bestimmt werden. Trotz der nicht vorhandenen Absolutkalibration für diese Konzentration konnten dank des neu eingeführten Parameters kappa eine Dehydrierung der Mizellen mit steigender Temperatur abgeschätzt, sowie eine Hysterese zwischen dem Heizen und Abkühlen festgestellt werden. Für die Konzentration von 10 wtp wurden kleinere Temperaturschritte gewählt und die Messungen zusätzlich absolut kalibriert. Es wurden die Größen und Streulängendichten SLD der Unimere und Mizellen präzise bestimmt und ein vollständiges Form-Phasendiagramm erstellt. Auch für diese Konzentration konnte eine Hysterese eindeutig an der Größe, SLD und am Parameter kappa gezeigt werden, sowie eine Dehydrierung des Mizellenkerns. Dies beweist, dass der Parameter kappa geeignet ist, um bei nicht absolut kalibrierten Messungen, Aussagen über die Hydrierung und Hysterese komplexer Kern-Hülle Modelle zu machen. Für die Konzentration von 30 wtp konnte zwischen 23°C und 35°C eine FCC Struktur nachgewiesen werden. Dabei vergrößert sich die Gitterkonstante der FCC Struktur von 260 A auf 289 A in Abhängigkeit der Temperatur.
Durch das Mischen zweier Lösungen, zum einen CdCl2 und 30 wtp P123 und zum anderen Na2S und 30 wtp P123, konnte CdS erfolgreich stabilisiert werden. Mit einer Kamera wurde die Gelbfärbung der Lösung, und somit die Bildung des CdS, in Abhängigkeit der Zeit untersucht. Es konnte festgestellt werden, dass das Bilden der CdS Nanopartikel je nach Konzentration und Temperierprogramm zwischen 30 und 300 Sekunden dauert und einer logistischen Wachstumsfunktion folgt. Höhere Konzentrationen CdS bewirken einen schnelleren Anstieg der Wachstumsfunktion. Mittels UV-Vis Spektroskopie konnte gezeigt werden, dass die Bandlücke von CdS mit steigender Konzentration konstant bei 2,52 eV bleibt. Eine solche Verschiebung der Bandlücke von ungefähr 0,05 eV im Vergleich zum Festkörper, deutet auf einen CdS Partikeldurchmesser von 80A hin. Mit SAXS konnte gezeigt werden, dass sich die flüssigkristalline Struktur des P123 bei zwei verschiedenen Konzentrationen CdS, von 0,005 und 0,1 M, nicht ändert. Das CdS wird zwischen den Mizellen, also durch die Bildung des Flüssigkristalls, und im Kern der Mizelle aufgrund seiner Hydrophobizität stabilisiert. Die Anfangs definierten Kriterien für eine erfolgreiche Stabilisierung wurden erfüllt.
P123 ist ein hervorragend geeignetes Polymer, um hydrophobes CdS, sowohl durch die Bildung eines Flüssigkristalls, als auch im Kern der Mizelle zu stabilisieren.
The projects presented in this thesis cover the examination of the electronic and structural properties of organic thin films at noble metal-organic interfaces. Angle-resolved photoemission spectroscopy is used as the primary investigative tool due to the connection of the emitted photoelectrons to the electronic structure of the sample. The surveyed materials are of relevance for fundamental research and practical applications on their own, but also serve as archetypes for the photoemission techniques presented throughout the four main chapters of this thesis. The techniques are therefore outlined with their adaptation to other systems in mind and a special focus on the proper description of the final state.
The most basic description of the final state that is still adequate for the evaluation of photoemission data is a plane wave. Its simplicity enables a relatively intuitive interpretation of photoemission data, since the initial and final state are related to one another by a Fourier transform and a geometric factor in this approximation. Moreover, the initial states of some systems can be reconstructed in three dimensions by combining photoemission measurements at various excitation energies. This reconstruction can even be carried out solely based on experimental data by using suitable iterative algorithms.
Since the approximation of the final state in the photoemission process by a plane wave is not valid in all instances, knowledge on the limitations of its applicability is indispensable. This can be gained by a comparison to experimental data as well as calculations with a more detailed description of the photoemission final state. One possible appraoch is based on independently emitting atoms where the coherent superposition of partial, atomic final states produces the total final state. This approach can also be used for more intricate studies on organic thin films. To this end, experimental data can be related to theoretical calculations to gain extensive insights into the structural and electronic properties of molecules in organic thin films.
In a comprehensive study, we demonstrate the performance and typical application scenarios for laboratory-based nano-computed tomography in materials research on various samples. Specifically, we focus on a projection magnification system with a nano focus source. The imaging resolution is quantified with common 2D test structures and validated in 3D applications by means of the Fourier Shell Correlation. As representative application examples from nowadays material research, we show metallization processes in multilayer integrated circuits, aging in lithium battery electrodes, and volumetric of metallic sub-micrometer fillers of composites. Thus, the laboratory system provides the unique possibility to image non-destructively structures in the range of 170–190 nanometers, even for high-density materials.
Since the early days of Dirac flux quantization, magnetic monopoles have been sought after as a potential corollary of quantized electric charge. As opposed to magnetic monopoles embedded into the theory of electromagnetism, Weyl semimetals (WSM) exhibit Berry flux monopoles in reciprocal parameter space. As a function of crystal momentum, such monopoles locate at the crossing point of spin-polarized bands forming the Weyl cone. Here, we report momentum-resolved spectroscopic signatures of Berry flux monopoles in TaAs as a paradigmatic WSM. We carried out angle-resolved photoelectron spectroscopy at bulk-sensitive soft X-ray energies (SX-ARPES) combined with photoelectron spin detection and circular dichroism. The experiments reveal large spin- and orbital-angular-momentum (SAM and OAM) polarizations of the Weyl-fermion states, resulting from the broken crystalline inversion symmetry in TaAs. Supported by first-principles calculations, our measurements image signatures of a topologically non-trivial winding of the OAM at the Weyl nodes and unveil a chirality-dependent SAM of the Weyl bands. Our results provide directly bulk-sensitive spectroscopic support for the non-trivial band topology in the WSM TaAs, promising to have profound implications for the study of quantum-geometric effects in solids. Weyl semimetals exhibit Berry flux monopoles in momentum-space, but direct experimental evidence has remained elusive. Here, the authors reveal topologically non-trivial winding of the orbital-angular-momentum at the Weyl nodes and a chirality-dependent spin-angular-momentum of the Weyl bands, as a direct signature of the Berry flux monopoles in TaAs.
Spin-spin interactions in organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) are pivotal because radiative recombination is largely determined by triplet-to-singlet conversion, also called reverse intersystem crossing (RISC). To explore the underlying process, we apply a spin-resonance spectral hole-burning technique to probe electroluminescence. We find that the triplet exciplex states in OLEDs are highly spin-polarized and show that these states can be decoupled from the heterogeneous nuclear environment as a source of spin dephasing and can even be coherently manipulated on a spin-spin relaxation time scale T-2* of 30 ns. Crucially, we obtain the characteristic triplet exciplex spin-lattice relaxation time T-1 in the range of 50 mu s, which far exceeds the RISC time. We conclude that slow spin relaxation rather than RISC is an efficiency-limiting step for intermolecular donor:acceptor systems. Finding TADF emitters with faster spin relaxation will benefit this type of TADF OLEDs.
Simultaneous measurements of 3D wall shear stress and pulse wave velocity in the murine aortic arch
(2021)
Purpose
Wall shear stress (WSS) and pulse wave velocity (PWV) are important parameters to characterize blood flow in the vessel wall. Their quantification with flow-sensitive phase-contrast (PC) cardiovascular magnetic resonance (CMR), however, is time-consuming. Furthermore, the measurement of WSS requires high spatial resolution, whereas high temporal resolution is necessary for PWV measurements. For these reasons, PWV and WSS are challenging to measure in one CMR session, making it difficult to directly compare these parameters. By using a retrospective approach with a flexible reconstruction framework, we here aimed to simultaneously assess both PWV and WSS in the murine aortic arch from the same 4D flow measurement.
Methods
Flow was measured in the aortic arch of 18-week-old wildtype (n = 5) and ApoE\(^{−/−}\) mice (n = 5) with a self-navigated radial 4D-PC-CMR sequence. Retrospective data analysis was used to reconstruct the same dataset either at low spatial and high temporal resolution (PWV analysis) or high spatial and low temporal resolution (WSS analysis). To assess WSS, the aortic lumen was labeled by semi-automatically segmenting the reconstruction with high spatial resolution. WSS was determined from the spatial velocity gradients at the lumen surface. For calculation of the PWV, segmentation data was interpolated along the temporal dimension. Subsequently, PWV was quantified from the through-plane flow data using the multiple-points transit-time method. Reconstructions with varying frame rates and spatial resolutions were performed to investigate the influence of spatiotemporal resolution on the PWV and WSS quantification.
Results
4D flow measurements were conducted in an acquisition time of only 35 min. Increased peak flow and peak WSS values and lower errors in PWV estimation were observed in the reconstructions with high temporal resolution. Aortic PWV was significantly increased in ApoE\(^{−/−}\) mice compared to the control group (1.7 ± 0.2 versus 2.6 ± 0.2 m/s, p < 0.001). Mean WSS magnitude values averaged over the aortic arch were (1.17 ± 0.07) N/m\(^2\) in wildtype mice and (1.27 ± 0.10) N/m\(^2\) in ApoE\(^{−/−}\) mice.
Conclusion
The post processing algorithm using the flexible reconstruction framework developed in this study permitted quantification of global PWV and 3D-WSS in a single acquisition. The possibility to assess both parameters in only 35 min will markedly improve the analyses and information content of in vivo measurements.
Two-dimensional triangular lattices of group IV adatoms on semiconductor substrates provide a rich playground for the investigation of Mott-Hubbard physics. The possibility to combine various types of adatoms and substrates makes members of this material class versatile model systems to study the influence of correlation strength, band filling and spin-orbit coupling on the electronic structure - both experimentally and with dedicated many-body calculation techniques. The latter predict exotic ground states such as chiral superconductivity or spin liquid behavior for these frustrated lattices, however, experimental confirmation is still lacking. In this work, three different systems, namely the \(\alpha\)-phases of Sn/SiC(0001), Pb/Si(111), and potassium-doped Sn/Si(111) are investigated with scanning tunneling microscopy and photoemission spectroscopy in this regard. The results are potentially relevant for spintronic applications or quantum computing.
For the novel group IV triangular lattice Sn/SiC(0001), a combined experimental and theoretical study reveals that the system features surprisingly strong electronic correlations because they are boosted by the substrate through its partly ionic character and weak screening capabilities. Interestingly, the spectral function, measured for the first time via angle-resolved photoemission, does not show any additional superstructure beyond the intrinsic \(\sqrt{3} \times \sqrt{3} R30^{\circ}\) reconstruction, thereby raising curiosity regarding the ground-state spin pattern.
For Pb/Si(111), preceding studies have noted a phase transition of the surface reconstruction from \(\sqrt{3} \times \sqrt{3} R30^{\circ}\) to \(3 \times 3\) at 86 K. In this thesis, investigations of the low-temperature phase with high-resolution scanning tunneling microscopy and spectroscopy unveil the formation of a charge-ordered ground state. It is disentangled from a concomitant structural rearrangement which is found to be 2-up/1-down, in contrast to previous predictions. Applying an extended variational cluster approach, a phase diagram of local and nonlocal Coulomb interactions is mapped out. Based on a comparison of theoretical spectral functions with scattering vectors found via quasiparticle interference, Pb/Si(111) is placed in said phase diagram and electronic correlations are found to be the driving force of the charge-ordered state.
In order to realize a doped Mott insulator in a frustrated geometry, potassium was evaporated onto the well-known correlated Sn/Si(111) system. Instead of the expected insulator-to-metal transition, scanning tunneling spectroscopy data indicates that the electronic structure of Sn/Si(111) is only affected locally around potassium atoms while a metallization is suppressed. The potassium atoms were found to be adsorbed on empty \(T_4\) sites of the substrate which eventually leads to the formation of two types of K-Sn alloys with a relative potassium content of 1/3 and 1/2, respectively. Complementary measurements of the spectral function via angle-resolved photoemission reveal that the lower Hubbard band of Sn/Si(111) gradually changes its shape upon potassium deposition. Once the tin and potassium portion on the surface are equal, this evolution is complete and the system can be described as a band insulator without the need to include Coulomb interactions.
Tensor tomography is fundamentally based on the assumption of a both anisotropic and linear contrast mechanism. While the X-ray or neutron dark-field contrast obtained with Talbot(-Lau) interferometers features the required anisotropy, a preceding detailed study of dark-field signal origination however found its specific orientation dependence to be a non-linear function of the underlying anisotropic mass distribution and its orientation, especially challenging the common assumption that dark-field signals are describable by a function over the unit sphere. Here, two approximative linear tensor models with reduced orientation dependence are investigated in a simulation study with regard to their applicability to grating based X-ray or neutron dark-field tensor tomography. By systematically simulating and reconstructing a large sample of isolated volume elements covering the full range of feasible anisotropies and orientations, direct correspondences are drawn between the respective tensors characterizing the physically based dark-field model used for signal synthesization and the mathematically motivated simplified models used for reconstruction. The anisotropy of freely rotating volume elements is thereby confirmed to be, for practical reconstruction purposes, approximable both as a function of the optical axis' orientation or as a function of the interferometer's grating orientation. The eigenvalues of the surrogate models' tensors are found to exhibit fuzzy, yet almost linear relations to those of the synthesization model. Dominant orientations are found to be recoverable with a margin of error on the order of magnitude of 1 degrees. Although the input data must adequately address the full orientation dependence of dark-field anisotropy, the present results clearly support the general feasibility of quantitative X-ray dark-field tensor tomography within an inherent yet acceptable statistical margin of uncertainty.
Verlustarmer Ladungsträgertransport ist für die Realisierung effizienter und kleiner elektronischer Bauteile von großem Interesse. Dies hilft entstehende Wärme zu minimieren und den Energieverbrauch gleichzeitig zu reduzieren. Einzelne Streuprozesse, die den Verlust bei Ladungsträgertransport bestimmen, laufen jedoch auf Längenskalen von Nano- bis Mikrometern ab. Um diese detailliert untersuchen zu können, bedarf es Messmethoden mit hoher zeitlicher oder örtlicher Auflösung. Für Letztere gibt es wenige etablierte Experimente, häufig basierend auf der Rastertunnelmikroskopie, welche jedoch verschiedenen Einschränkungen unterliegen. Um die Möglichkeiten der Detektion von Ladungsträgertransport auf Distanzen der mittleren freien Weglänge und damit im ballistischen Regime zu verbessern, wurde im Rahmen dieser Dissertation die Molekulare Nanosonde charakterisiert und etabliert. Diese Messmethode nutzt ein einzelnes Molekül als Detektor für Ladungsträger, welche mit der Sondenspitze des Rastertunnelmikroskops (RTM) wenige Nanometer entfernt vom Molekül in das untersuchte Substrat injiziert werden. Die hohe Auflösung des RTM in Kombination mit der geringen Ausdehnung des molekularen Detektors ermöglicht dabei atomare Kontrolle von Transportpfaden über wenige Nanometer. Der erste Teil dieser Arbeit widmet sich der Charakterisierung der Molekularen Nanosonde. Hierfür werden zunächst die elektronischen Eigenschaften dreier Phthalocyanine mittels Rastertunnelspektroskpie untersucht, welche im Folgenden zur Charakterisierung des Moleküls als Detektor Anwendung finden. Die anschließende Analyse der Potentiallandschaft der Tautomerisation von H2Pc und HPc zeigt, dass die NH- Streckschwinung einem effizienten Schaltprozess zu Grunde liegt. Darauf basierend wird der Einfluss der Umgebung anhand von einzelnen Adatomen sowie des Substrats selbst auf den molekularen Schalter analysiert. In beiden Fällen zeigt sich eine signifikante Änderung der Potentiallandschaft der Tautomerisation. Anschließend wird der Einfluss geometrischer Eigenschaften des Moleküls selbst untersucht, wobei sich eine Entkopplung vom Substrat auf Grund von dreidimensionalen tert-Butyl-Substituenten ergibt. Zusätzlich zeigt sich bei dem Vergleich von Naphthalocyanin zu Phthalocyanin der Einfluss lateraler Ausdehnung auf die Detektionsfläche, was einen nicht-punktförmigen Detektor bestätigt. Im letzten Abschnitt werden zwei Anwendungen der Molekularen Nanosonde präsentiert. Zunächst wird mit Phthalocyanin auf Ag(111) demonstriert, dass die Interferenz von ballistischen Ladungsträgern auf Distanzen von wenigen Nanometern mit dieser Technik detektierbar ist. Im zweiten Teil zeigt sich, dass der ballistische Transport auf einer Pd(110)-Oberfläche durch die anisotrope Reihenstruktur auf atomarer Skala moduliert wird.
This thesis aims to investigate the form-phase diagram of aqueous solutions of the triblock copolymer Pluronic P123 focusing on its high-temperature phases. P123 is based on polyethylene as well as polypropylene oxide blocks and shows a variety of di erent temperaturedependent micelle morphologies or even lyotropic liquid crystal phases in aqueous solutions. Besides the already well-studied spherical aggregates at intermediate temperatures, the size and internal structure of both worm-like and lamellar micelles, which appear near the cloud point, is determined using light, neutron and X-ray scattering. By combining the results of time-resolved dynamic light as well as small-angle neutron and X-ray scattering experiments, the underlying structural changes and kinetics of the sphere-to-worm transition were studied supporting the random fusion process, which is proposed in literature. For temperatures near the cloud point, it was observed that aqueous P123 solutions below the critical crystallization concentration gelate after several hours, which is linked to the presence and structure of polymeric surface layers on the sample container walls as shown by neutron re ectometry
measurements. Using a hierarchical model for the lamellar micelles including their periodicity as well as domain and overall size, it is possible to unify the existing results in literature and propose a direct connection between the near-surface and bulk properties of P123 solutions at temperatures near the cloud point.
Neue physikalische Erkenntnisse vervollständigen die Sicht auf die Welt und erschließen gleichzeitig Wege für Folgeexperimente und technische Anwendungen. Das letzte Jahrzehnt der Festkörperforschung war vom zunehmenden Fokus der theoretischen und experimentellen Erkundung topologischer Materialien geprägt. Eine fundamentale Eigenschaft ist ihre Resistenz gegenüber solchen Störungen, welche spezielle physikalische Symmetrien nicht verletzen. Insbesondere die Topologischen Isolatoren - Halbleiter mit isolierenden Volumen- sowie gleichzeitig leitenden und spinpolarisierten Oberflächenzuständen - sind vielversprechende Kandidaten zur Realisierung breitgefächerter spintronischer Einsatzgebiete. Bis zur Verwirklichung von Quantencomputern und anderer, heute noch exotisch anmutender Konzepte bedarf es allerdings ein umfassenderes Verständnis der grundlegenden, physikalischen Zusammenhänge. Diese kommen vor allem an Grenzflächen zum Tragen, weshalb oberflächensensitive Methoden bei der Entdeckung der Topologischen Isolatoren eine wichtige Rolle spielten.
Im Rahmen dieser Arbeit werden daher strukturelle, elektronische und magnetische Eigenschaften Topologischer Isolatoren mittels Tieftemperatur-Rastertunnelmikroskopie und -spektroskopie sowie begleitenden Methoden untersucht.
Die Veränderung der Element-Ausgangskonzentration während dem Wachstum des prototypischen Topologischen Isolators Bi2Te3 führt zur Realisierung eines topologischen p-n Übergangs innerhalb des Kristalls. Bei einem spezifischen Verhältnis von Bi zu Te in der Schmelze kommt es aufgrund unterschiedlicher Erstarrungstemperaturen der Komponenten zu einer Ansammlung von Bi- und Te-reichen Gegenden an den gegenüberliegenden Enden des Kristalls. In diesen bildet sich infolge des jeweiligen Elementüberschusses durch Kristallersetzungen und -fehlstellen eine Dotierung des Materials aus. Daraus resultiert die Existenz eines Übergangsbereiches, welcher durch Transportmessungen verifiziert werden kann. Mit der räumlich auflösenden Rastertunnelmikroskopie wird diese Gegend lokalisiert und strukturell sowie elektronisch untersucht. Innerhalb des Übergangsbereiches treten charakteristische Kristalldefekte beider Arten auf - eine Defektunterdrückung bleibt folglich aus. Dennoch ist dort der Beitrag der Defekte zum Stromtransport aufgrund ihres gegensätzlichen Dotiercharakters vernachlässigbar, sodass der topologische Oberflächenzustand die maßgeblichen physikalischen Eigenschaften bestimmt. Darüber hinaus tritt der Übergangsbereich in energetischen und räumlichen Größenordnungen auf, die Anwendungen bei Raumtemperatur denkbar machen.
Neben der Veränderung Topologischer Isolatoren durch den gezielten Einsatz intrinsischer Kristalldefekte bieten magnetische Störungen die Möglichkeit zur Prüfung des topologischen Oberflächenzustandes auf dessen Widerstandsfähigkeit sowie der gegenseitigen Wechselwirkungen. Die Zeitumkehrinvarianz ist ursächlich für den topologischen Schutz des Oberflächenzustandes, weshalb magnetische Oberflächen- und Volumendotierung diese Symmetrie brechen und zu neuartigem Verhalten führen kann.
Die Oberflächendotierung Topologischer Isolatoren kann zu einer starken Bandverbiegung und einer energetischen Verschiebung des Fermi-Niveaus führen. Bei einer wohldosierten Menge der Adatome auf p-dotiertem Bi2Te3 kommt die Fermi-Energie innerhalb der Volumenzustands-Bandlücke zum Liegen. Folglich wird bei Energien rund um das Fermi-Niveau lediglich der topologische Oberflächenzustand bevölkert, welcher eine Wechselwirkung zwischen den Adatomen vermitteln kann. Für Mn-Adatome kann Rückstreuung beobachtet werden, die aufgrund der Zeitumkehrinvarianz in undotierten Topologischen Isolatoren verboten ist. Die überraschenderweise starken und fokussierten Streuintensitäten über mesoskopische Distanzen hinweg resultieren aus der ferromagnetischen Kopplung nahegelegener Adsorbate, was durch theoretische Berechnungen und Röntgendichroismus-Untersuchungen bestätigt wird. Gleichwohl wird für die Proben ein superparamagnetisches Verhalten beobachtet.
Im Gegensatz dazu führt die ausreichende Volumendotierung von Sb2Te3 mit V-Atomen zu einem weitreichend ferromagnetischen Verhalten. Erstaunlicherweise kann trotz der weitläufig verbreiteten Theorie Zeitumkehrinvarianz-gebrochener Dirac-Zustände und der experimentellen Entdeckung des Anormalen Quanten-Hall-Effektes in ähnlichen Probensystemen keinerlei Anzeichen einer spektroskopischen Bandlücke beobachtet werden. Dies ist eine direkte Auswirkung der dualen Natur der magnetischen Adatome: Während sie einerseits eine magnetisch induzierte Bandlücke öffnen, besetzen sie diese durch Störstellenresonanzen wieder. Ihr stark lokaler Charakter kann durch die Aufnahme ihrer räumlichen Verteilung aufgezeichnet werden und führt zu einer Mobilitäts-Bandlücke, deren Indizien durch vergleichende Untersuchungen an undotiertem und dotiertem Sb2Te3 bestätigt werden.
Magnetic random access memory (MRAM) technology aims to replace dynamic RAM (DRAM) due to its significantly lower power consumption and non-volatility [Dong08]. During the last couple of years the commercial focus was set on spin-transfer torque MRAM (STT-MRAM) systems, where a current is pushed through a ferromagnetic (FM) free layer and a reference layer which are separated by an insulator. The free layer can be set to parallel or anti-parallel depending on the current direction [Kim11]. Unfortunately these currents have to be quite high which could lead to damages of the tunnel barrier of the magnetic tunnel junction resulting in higher power consumption as well as reliability issues. At this point a new effect, where the current is passed below the ferromagnetic layer stack, can be exploited to change the direction of the free layer magnetization. The effect is known as spin-orbit torque (SOT) and describes the transfer of angular momentum onto an adjacent magnetization either by the spin Hall effect (SHE) or inverse spin galvanic effect (iSGE) [Manchon19]. The latter describes a spin accumulation due to a current. This is similar to the process of spin accumulation in TIs, where a current corresponds to an effective spin due to spin-momentum locking [Qi11]. Thus TIs exhibit a high current-to-spin conversion rate, which makes them a promising material system for SOT experiments. Among all TIs it is HgTe, which can be reliably grown as an insulator. This thesis covers the development of a working device for SOT measurements (SOT-device) in a CdTe/CdHgTe/HgTe/CdHgTe heterostructure. It involves the development of a tunnel barrier (ZrOx) as well as the investigation of the behavior of a ferromagnetic layer stack on top of etched HgTe. The main result of this work is the successful construction and evaluation of a working SOT-device, which exhibits the up to date most efficient switching of in-plane magnetized ferromagnetic layer stacks.
In order to avoid hybridization between HgTe and the adjacent ferromagnetic atoms, which would cause a breakdown of the topological surface state, it is necessary to implement a thin tunnel barrier in between the TI and free layer [Zhang16]. Aside from hybridization a tunnel barrier avoids shunting of the current, that is pushed on the surface of the HgTe/CdHgTe interface. Thus a bigger part of the current can be used for spin accumulation and, at the same time, the resistance measurement of the ferromagnetic layer stack is not perturbed. In chapter 3 the focus is set on investigating the tunneling characteristics of ZrOx on top of dry etched HgTe. Thin barriers are used as the interaction of the current generated spin and the adjacent magnetization decreases with distance. On the other hand too small insulator thicknesses lead to leakage currents which disturb heavily the measurement of the resistance of the ferromagnetic layer stack. Thus an optimum thickness of 10 ALD cycles (\(d\approx 1.6\rm\, nm\)) is determined which yields a resistance area product of \(R\cdot A \approx 3\rm\, k\Omega\mu m^{2}\). This corresponds to a tunneling resistance of \(R_{T}\approx 20\rm\, k\Omega\) over a structure surface of \(A_{T} = 0.12\rm\, \mu m^2\). Multiple samples with different thicknesses have been produced. All samples have been examined on their tunneling behavior. The resistance area product as a function of thickness shows a linear behavior on a logarithmic scale. Furthermore all working samples show non-linear I-V curves as well as parabolic dI/dV-curves. Additionally the tunneling resistance \(R_{T}\) increases with decreasing temperature. All above mentioned properties are typical for tunnel barriers which do not include pinholes [Jonsson00]. The last part of chapter 3 deals with thermal properties of HgTe. By measuring the second harmonic of a biasing AC current in the channel below the tunnel barrier it is attempted to extract the diffusion thermopower of the heated electrons. Unfortunately the measured signal showed a far superior contribution of the first harmonic. According to electric circuit simulations a small asymmetry in the barrier (penetration and leaving point of electrons) could be responsible for this behavior.
A ferromagnetic layer stack, consisting of PY/Cu/CoFe, serves as a sensor for magnetization changes due to external fields and current induced spin accumulations. The layer stack exhibits a giant magnetoresistance (GMR) which has been measured by a resistance bridge. The biggest peculiarity in depositing a GMR stack on top of HgTe is that its easy axis forms along only one of the crystal axes (\((110)\) or \((1\overline{1}0)\)). The reason for this anisotropy is still unclear. Sources such as an influence of the terminating material, miscut, furrows during IBE or sputter ripples have been ruled out. It can be speculated that the surface states due to HgTe might have an influence on the development of this easy axis but this would need further investigation. A consequence of this unexpected anisotropy is that every CdTe/CdHgTe/HgTe/CdHgTe wafer has first to be characterized in SQUID in order to find the easy axis. A ferromagnetic resonance (FMR) measurement confirmed this observation. The shape of the ferromagnetic layer stack is chosen to be an ellipse in order to support the easy axis direction by shape anisotropy. Over 8 million ellipses are used to generate a SQUID signal of \(m > 10^{-5}\rm\, emu\). This is sufficient to extract the main characteristics of an average nano pillar under the influence of an external magnetic field. As in the case of bigger structures the ellipse shaped structure shows a step-like behavior. A measured minor loop confirms the existence of the irreversible anti-parallel stable magnetic state. Furthermore this state persists for both directions at \(m=0\) resulting in an anti-ferromagnetic coupling between Py and CoFe.
The geometry of the SOT-device is chosen in such a way that the current induced spin aligns either parallel or anti-parallel to the effective magnetic field \(\vec{B}_{eff}=\vec{B}_{ext}+\vec{B}_{aniso}+\vec{B}_{shape}\), which acts on the pillar. Due to interaction of the spin with the adjacent magnetization of Py the magnetization direction gets changed by a torque \(\vec{T}\). In general this torque can be decomposed into two components a field-like torque \(\vec{\tau}_{FL}\) and a damping-like torque \(\vec{\tau}_{DL}\) [Manchon19]. In the case of TIs \(\vec{T}\) is additionally depending on the z-component of \(\vec{m}\) [Ndiaye17]. In our case the magnetization is lying in the sample plane (\(m_{z}=0\)) which results in \(\vec{\tau}_{DL}=0\). Thus, in the case of \(\vec{S}\parallel\left(\vec{\hat{z}}\times\vec{j}\right)\) and \(\vec{j}\parallel\vec{\hat{y}}\), the only spin dependent effective magnetic field is \(\vec{B}_{FL}=\tau_{FL}\cdot\vec{\hat{x}}\) which is lying parallel or anti-parallel to \(\vec{B}_{eff}\). The evaluation of \(\vec{B}_{FL}\) can therefore be done in the following manner. First a high \(B_{ext}\) has to be set along the easy axis of the pillar. Then \(B_{ext}\) has to be reduced just a few \(\rm\, Oe\) before the switching occurs at the magnetic field \(B_{ext,0}\). At the magnetic field \(\Delta B = B_{ext}-B_{ext,0}\approx 0.5\rm\, Oe\) the lower resistive state should be stable over a longer time range (\(10-30\rm\, min\)) in order to exclude switching due to fluctuations. Now a positive or negative current can be pushed through the channel below the pillar. For one of the two current directions the magnetization of Py switches. It is therefore not a thermal effect that drives the change of \(\vec{m}\). Current densities that are able to switch \(\vec{m}\) at small \(\Delta B\neq 0\) lie in the range of \(j\approx 10^{4}\rm\, A/cm^{2}\). In all experiments the switching efficiency \(\Delta B/j\) decreases with rising \(j\). Furthermore the efficiency as a function of \(j\) depends on the temperature as \(\Delta B/j\) values tend to be up to 20 times higher at \(T=1.8\rm\, K\) and \(j\approx 0\) than at \(T=4.2\rm\, K\). This temperature dependence suggests that switching occurs not due to Oersted fields. Furthermore the Biot-Savart fields had been calculated for four different models: an infinite long rectangular wire, two infinite planes, a full volume and two thin volume planes. Every model shows an efficiency, which is at least three times lower than the observation.
The highest efficiencies in our samples show up to 10 times higher values than in heavy-metal/ferromagnets heterostructures. In contrast to measurement procedures of most other groups our method leads to direct determination of SOT parameters like the effective magnetic field \(\vec{B}_{FL}\). Other groups make use of spin-transfer FMR (ST-FMR) where they AC bias their structure and extract SOT parameters (like \(\tau_{FL}\) and \(\tau_{DL}\)) from second harmonics by fitting theoretical models. Material systems consisting of TIs and magnetic insulators (MIs) on the other hand show 10 times higher efficiencies [Khang18,Li19]. In those cases the magnetization points out of the sample plane which is conceptually different from in-plane magnetic anisotropy geometries like in our case. The greatest benefit in-plane magnetic anisotropy systems is its easy realisation [Bhatti17]. Here only an elliptical shape has to be lithographically implemented instead of conducting research on the appropriate combination of material systems that result in perpendicular magnetic anisotropies [Apalkov16]. Despite the fact that in our case only \(\vec{\tau}_{FL}\) acts as the driving force for changing \(m\) our device still exhibits the up to date highest efficiencies in the class of in-plane magnetized anisotropies of all material classes ever recorded.
Das Ziel dieser Arbeit war die Entwicklung und Weiterentwicklung von Laserlichtquellen basierend auf der Interbandkaskadentechnologie in einem Wellenlängenbereich von ca. 3 bis 6 µm. Der Fokus lag dabei auf der Entwicklung von Kantenemitter-Halbleiterlasern, welche bei verschiedensten Emissionswellenlängen erfolgreich hergestellt werden konnten. Dabei wurde auf jeweilige Herausforderungen eingegangen, welche entweder durch die Herstellung selbst oder der anwendungstechnischen Zielsetzung bedingt war. Im Rahmen dieser Arbeit wurden verschiedene, spektral einzelmodige Halbleiterlaser im angesprochenen Wellenlängenbereich entwickelt und hergestellt. Basierend auf dem jeweiligen Epitaxiematerial und der angestrebten Emissionswellenlänge wurden Simulationen der optischen Lasermode durchgeführt und die grundlegenden für die Herstellung notwendigen Parameter bestimmt und experimentell umgesetzt. Des Weiteren wurden die verwendeten Verfahren für den jeweiligen Herstellungsprozess angepasst und optimiert. Das umfasst die in den ersten Kapiteln beschriebenen Schritte wie optische Lithografie, Elektronenstrahllithografie, reaktives Trockenätzen und verschiedene Arten der Materialdeposition. Mit einer Emissionswellenlänge von 2,8 µm wurde beispielsweise der bislang kurzwelligste bei Raumtemperatur im Dauerstrichbetrieb betriebene einzelmodige Interbandkaskadenlaser hergestellt. Dessen Leistungsmerkmale sind mit Diodenlasern im entsprechenden Emissionsbereich vergleichbar. Somit ergänzt die Interbandkaskadentechnologie bestehende Technologien nahtlos und es ist eine lückenlose Wellenlängenabdeckung bis in den mittleren Infrarotbereich möglich. Je nach Herstellungsprozess wurde außerdem auf die verteilte Rückkopplung eingegangen und die Leistungsfähigkeit des verwendeten Metallgitterkonzeptes anhand von Messungen an spektral einzelmodigen Bauteile aufgezeigt. Es wurden aber auch die je nach Zielsetzung unterschiedlichen Herausforderungen aufgezeigt und diskutiert. Für eine Anwendung wurden spezielle Laserchips mit zwei einzelmodigen Emissionswellenlängen bei 3928 nm und 4009 nm entwickelt. Die beiden Wellenlängen sind für die Detektion von Schwefeldioxid und Schwefelwasserstoff geeignet, welche zur Überwachung und Optimierung der Schwefelgewinnung durch das Claus-Verfahren notwendig sind. Bei der Umsetzung wurden auf einzelnen Chips zwei Laseremitter in einem Abstand von 70 µm platziert und mit je einem Metallgitter versehen. Das verwendete Epitaxiematerial war so konzipiert, dass es optimal für beide Zielwellenlängen verwendet werden kann. Die geforderten Eigenschaften wurden erfüllt und die Bauteile konnten erfolgreich hergestellt werden. Die Emissionseigenschaften und das spektrale Verhalten wurde bei beiden Zielwellenlängen bestimmt. Einzeln betrachtet erfüllen beide Emitter die notwendigen Eigenschaften um für spektroskopische Anwendungen eingesetzt werden zu können. Ergänzend wurde zum einen das Abstimmverhalten der Emissionswellenlänge in Abhängigkeit der Modulationsfrequenz des Betriebsstromes untersucht und zusätzlich die thermische Abhängigkeit der Betriebsparameter beider Kanäle zueinander bestimmt. Diese Abhängigkeit ist für eine simultane Messung mit beiden Kanälen notwendig. Das Konzept mit mehreren Stegwellenleitern pro Laserchip wurde in einem weiteren Fall noch stärker ausgearbeitet. Denn je nach Komplexität eines Gasgemisches sind zur Bestimmung der einzelnen Komponenten mehr Messpunkte bzw. Wellenlängen notwendig. Im zweiten Fall ist die Analyse der Kohlenwasserstoffe Methan, Ethan, Propan, Butan, Iso-Butan, Pentan und Iso-Pentan von Interesse, welche als Hauptbestandteile von Erdgas z.B. in Erdgasaufbereitungsanlagen oder zur Bestimmung des Heizwertes analysiert werden müssen. Die genannten Kohlenwasserstoffe zeigen ein starkes Absorptionsverhalten im Wellenlängenbereich von 3,3 bis 3,5 µm. Auf dem entsprechend angepassten Interbandkaskadenmaterial wurden Bauteile mit neun Wellenleitern pro Laserchip hergestellt. Mithilfe der neun einzelmodigen Emissionskanäle konnte ein Bereich von bis zu 190 nm (21 meV, 167 cm-1) adressiert werden. Außerdem wurde der sich mit zunehmender Wellenlänge ändernde Schichtaufbau und dessen Einfluss auf die Bauteileigenschaften diskutiert. Die Leistungsdaten der langwelligsten Epitaxie waren im Vergleich deutlich schwächer. Um diesen Nachteil zu kompensieren, wurde eine spezielle Wellenleitergeometrie mit doppeltem Steg genutzt. Die Eigenschaften des Konzeptes wurden zuerst mittels Simulation untersucht und ein entsprechendes Herstellungsverfahren entwickelt. Mit der Simulation als Grundlage wurden die verschiedenen Prozessparameter über mehrere Prozessläufe iterativ optimiert und somit die Performance der Laser verbessert. Auch mit diesem Verfahren konnte ausreichende Kopplung an das Metallgitter erzielt werden. Abschließend wurden mit diesem Herstellungsverfahren einzelmodige Laser im Wellenlängenbereich von 5,9 bis über 6 Mikrometern realisiert. Diese Laser emittierten im Dauerstrichbetrieb bei einer maximalen Betriebstemperatur von -2 °C. Insgesamt wurde anhand der im Rahmen dieser Arbeit entwickelten Bauteilen und de ren Charakterisierung gezeigt, dass diese die Anforderungen von TLAS Anwendungen erfüllen. Jedoch konnte nur auf einen Teil der Möglichkeiten eingegangen werden, den die Interbandkaskadentechnologie bietet, denn die angesprochenen Einsatzgebiete stellen nur einzelne grundlegende Möglichkeiten dieser Technologie mit Schwerpunkt auf laserbasierte Lichtquellen dar. Zusammenfassend kann allerdings gesagt werden, dass sich die Interbandkaskadentechnologie etabliert hat. Gerade durch die gezeigten Leistungsdaten bei den Wellenlängen um 2,9 µm, 3,4 µm und 4,0 µm im Dauerstrichbetrieb bei Raumtemperatur wird ersichtlich, dass im Bereich der Sensorik die ICL Technologie in Bezug auf niedriger Strom- bzw. Leistungsaufnahme quasi konkurrenzlos ist. Sicherlich werden die Anwendungsgebiete in Zukunft noch vielfältiger. Denn es sind auf jeden Fall weitere Fortschritte in Richtung höherer Emissionswellenlängen, deutlich höherer Betriebstemperaturen, verbreiterte Emissionsbereiche oder gänzlich andere Bauteil Konzepte wie z.B. für Frequenzkämme bzw. Terahertz Anwendungen zu erwarten. Diese Entwicklung betrifft nicht nur den Einsatz als Lichtquelle, denn auch Interbandkaskadendetektoren bzw. Solarzellen wurden schon realisiert und werden weiterentwickelt.
Reduced Recombination Losses in Evaporated Perovskite Solar Cells by Postfabrication Treatment
(2021)
The photovoltaic perovskite research community has now developed a large set of tools and techniques to improve the power conversion efficiency (PCE). One such arcane trick is to allow the finished devices to dwell in time, and the PCE often improves. Herein, a mild postannealing procedure is implemented on coevaporated perovskite solar cells confirming a substantial PCE improvement, mainly attributed to an increased open-circuit voltage (V\(_{OC}\)). From a V\(_{OC}\) of around 1.11 V directly after preparation, the voltage improves to more than 1.18 V by temporal and thermal annealing. To clarify the origin of this annealing effect, an in-depth device experimental and simulation characterization is conducted. A simultaneous reduction of the dark saturation current, the ideality factor (n\(_{id}\)), and the leakage current is revealed, signifying a substantial impact of the postannealing procedure on recombination losses. To investigate the carrier dynamics in more detail, a set of transient optoelectrical methods is first evaluated, ascertaining that the bulk carrier lifetime is increased with device annealing. Second, a drift-diffusion simulation is used, confirming that the beneficial effect of the annealing has its origin in effective bulk trap passivation that accordingly leads to a reduction of Shockley–Read–Hall recombination rates.
This work revealed spin states that are involved in the light generation of organic light-emitting diodes (OLEDs) that are based on thermally activated delayed fluorescence (TADF). First, several donor:acceptor-based TADF systems forming exciplex states were investigated. Afterwards, a TADF emitter that shows intramolecular charge transfer states but also forms exciplex states with a proper donor molecule was studied. The primary experimental technique was electron paramagnetic resonance (EPR), in particular the advanced methods electroluminescence detected magnetic resonance (ELDMR), photoluminescence detected magnetic resonance (PLDMR) and electrically detected magnetic resonance (EDMR). Additional information was gathered from time-resolved and continuous wave photoluminescence measurements.
Organic light emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) utilize molecular systems with a small energy splitting between singlet and triplet states. This can either be realized in intramolecular charge transfer states of molecules with near‐orthogonal donor and acceptor moieties or in intermolecular exciplex states formed between a suitable combination of individual donor and acceptor materials. Here, 4,4′‐(9H,9′H‐[3,3′‐bicarbazole]‐9,9′‐diyl)bis(3‐(trifluoromethyl) benzonitrile) (pCNBCzoCF\(_{3}\)) is investigated, which shows intramolecular TADF but can also form exciplex states in combination with 4,4′,4′′‐tris[phenyl(m‐tolyl)amino]triphenylamine (m‐MTDATA). Orange emitting exciplex‐based OLEDs additionally generate a sky‐blue emission from the intramolecular emitter with an intensity that can be voltage‐controlled. Electroluminescence detected magnetic resonance (ELDMR) is applied to study the thermally activated spin‐dependent triplet to singlet up‐conversion in operating devices. Thereby, intermediate excited states involved in OLED operation can be investigated and the corresponding activation energy for both, intra‐ and intermolecular based TADF can be derived. Furthermore, a lower estimate is given for the extent of the triplet wavefunction to be ≥ 1.2 nm. Photoluminescence detected magnetic resonance (PLDMR) reveals the population of molecular triplets in optically excited thin films. Overall, the findings allow to draw a comprehensive picture of the spin‐dependent emission from intra‐ and intermolecular TADF OLEDs.
This work consists of two parts. On the one hand, it describes simulation and
measurement of the effect of contaminations of the detector gas on the performance
of particle detectors, with special focus on Micromegas detectors. On the other
hand, it includes the setup of a production site for the finalization of drift panels
which are going to be used in the ATLAS NSW. The first part augments these
two parts to give an introduction into the theoretical foundations of gaseous particle
detectors.
As a non-destructive testing method, X-ray imaging has proved to be suitable for the examination of a variety of objects. The measurement principle is based on the attenuation of X-rays caused by these objects. This attenuation can be recorded as shades of intensity using X-ray detectors and thus contains information about the inner structure of the investigated object. Since X-rays are electromagnetic waves, they also experience a change of phase in addition to their attenuation while penetrating an object. In general, imaging methods based on this effect are referred to as phase contrast imaging techniques. In the laboratory, the two mainly used methods are the propagation based phase contrast or in-line phase contrast and the grating interferometry.
While in-line phase contrast - under certain conditions - shows edge enhancement at interfaces due to interference, phase contrast in the grating interferometry is only indirectly measurable by the use of several gratings. In addition to phase contrast, grating interferometry provides access to the so-called dark-field imaging contrast, which measures the scattering of X-rays caused by an object.
These two imaging techniques, together with a novel concept of laboratory X-ray sources, the liquid-metal-jet, form the main part of this work. Compared to conventional X-ray sources, the liquid-metal-jet source offers higher brightness. The term brightness is defined by the number of X-ray photons per second, emitting area (area of the X-ray spot) and solid angle at which they are emitted.
On the basis of this source, a high resolution in-line phase contrast setup was partially developed in the scope of this work. Several computed tomographies show the feasibility of in-line phase contrast and the improvement of image quality by applying phase retrieval algorithms.
Moreover, the determination of optimized sample positions for in-line phase contrast imaging is treated at which the edge enhancement is maximized. Based on primitive fiber objects, this optimization has proven to be a good approximation.
With its high brightness in combination with a high spatial coherence, the liquid-metal-jet source is also interesting for grating interferometry. The development of such a setup is also part of this work. The overall concept and the characterization of the setup is presented as well as the applicability and its limits for the investigation of various objects.
Due to the very unique concept of this grating interferometer it was possible to realize a modified interferometer system by using a single grating only. Its concept and results are also presented in this work.
Furthermore, a grating interferometer based on a microfocus X-ray tube was tested regarding its performance. Thereby, parameters like the anode material, acquisition geometry and gratings were altered in order to find the advantages and disadvantages of each configuration.
Growth, ageing and atherosclerotic plaque development alter the biomechanical forces acting on the vessel wall. However, monitoring the detailed local changes in wall shear stress (WSS) at distinct sites of the murine aortic arch over time has been challenging. Here, we studied the temporal and spatial changes in flow, WSS, oscillatory shear index (OSI) and elastic properties of healthy wildtype (WT, n = 5) and atherosclerotic apolipoprotein E-deficient (Apoe\(^{−/−}\), n = 6) mice during ageing and atherosclerosis using high-resolution 4D flow magnetic resonance imaging (MRI). Spatially resolved 2D projection maps of WSS and OSI of the complete aortic arch were generated, allowing the pixel-wise statistical analysis of inter- and intragroup hemodynamic changes over time and local correlations between WSS, pulse wave velocity (PWV), plaque and vessel wall characteristics. The study revealed converse differences of local hemodynamic profiles in healthy WT and atherosclerotic Apoe\(^{−/−}\) mice, and we identified the circumferential WSS as potential marker of plaque size and composition in advanced atherosclerosis and the radial strain as a potential marker for vascular elasticity. Two-dimensional (2D) projection maps of WSS and OSI, including statistical analysis provide a powerful tool to monitor local aortic hemodynamics during ageing and atherosclerosis. The correlation of spatially resolved hemodynamics and plaque characteristics could significantly improve our understanding of the impact of hemodynamics on atherosclerosis, which may be key to understand plaque progression towards vulnerability.
Coupling N identical emitters to the same field mode is a well-established method to enhance light-matter interaction. However, the resulting √N boost of the coupling strength comes at the cost of a “linearized” (effectively semiclassical) dynamics. Here, we instead demonstrate a new approach for enhancing the coupling constant of a single quantum emitter, while retaining the nonlinear character of the light-matter interaction. We consider a single quantum emitter with N nearly degenerate transitions that are collectively coupled to the same field mode. We show that in such conditions an effective Jaynes-Cummings model emerges with a boosted coupling constant of order √N. The validity and consequences of our general conclusions are analytically demonstrated for the instructive case N=2. We further observe that our system can closely match the spectral line shapes and photon autocorrelation functions typical of Jaynes-Cummings physics, proving that quantum optical nonlinearities are retained. Our findings match up very well with recent broadband plasmonic nanoresonator strong-coupling experiments and will, therefore, facilitate the control and detection of single-photon nonlinearities at ambient conditions.
Atherosclerosis is an inflammatory disease of large and medium-sized arteries, characterized by the growth of atherosclerotic lesions (plaques). These plaques often develop at inner curvatures of arteries, branchpoints, and bifurcations, where the endothelial wall shear stress is low and oscillatory. In conjunction with other processes such as lipid deposition, biomechanical factors lead to local vascular inflammation and plaque growth. There is also evidence that low and oscillatory shear stress contribute to arterial remodeling, entailing a loss in arterial elasticity and, therefore, an increased pulse-wave velocity. Although altered shear stress profiles, elasticity and inflammation are closely intertwined and critical for plaque growth, preclinical and clinical investigations for atherosclerosis mostly focus on the investigation of one of these parameters only due to the experimental limitations. However, cardiovascular magnetic resonance imaging (MRI) has been demonstrated to be a potent tool which can be used to provide insights into a large range of biological parameters in one experimental session. It enables the evaluation of the dynamic process of atherosclerotic lesion formation without the need for harmful radiation. Flow-sensitive MRI provides the assessment of hemodynamic parameters such as wall shear stress and pulse wave velocity which may replace invasive and radiation-based techniques for imaging of the vascular
function and the characterization of early plaque development. In combination with inflammation imaging, the analyses and correlations of these parameters could not only significantly advance basic preclinical investigations of atherosclerotic lesion formation and progression, but also the diagnostic clinical evaluation for early identification of high-risk plaques, which are prone to rupture. In this review, we summarize the key applications of magnetic resonance imaging for the evaluation of plaque characteristics through flow sensitive and morphological measurements. The simultaneous measurements of functional and structural parameters will further preclinical research on atherosclerosis and has the potential to fundamentally improve the detection of inflammation and vulnerable plaques in patients.
We demonstrate single-photon emission with a low probability of multiphoton events of 5% in the C-band of telecommunication spectral range of standard silica fibers from molecular beam epitaxy grown (100)-GaAs-based structure with InAs quantum dots (QDs) on a metamorphic buffer layer. For this purpose, we propose and implement graded In content digitally alloyed InGaAs metamorphic buffer layer with maximal In content of 42% and GaAs/AlAs distributed Bragg reflector underneath to enhance the extraction efficiency of QD emission. The fundamental limit of the emission rate for the investigated structures is 0.5 GHz based on an emission lifetime of 1.95 ns determined from time-resolved photoluminescence. We prove the relevance of a proposed technology platform for the realization of non-classical light sources in the context of fiber-based quantum communication applications.
Bloch oscillations are a phenomenon well known from quantum mechanics where electrons in a lattice experience an oscillatory motion in the presence of an electric field gradient. Here, the authors report on Bloch oscillations of hybrid light−matter particles, called exciton‐polaritons (polaritons), being confined in an array of coupled microcavity waveguides. To this end, the waveguide widths and their mutual couplings are carefully designed such that a constant energy gradient is induced perpendicular to the direction of motion of the propagating polaritons. This technique allows us to directly observe and study Bloch oscillations in real‐ and momentum‐space. Furthermore, the experimental findings are supported by numerical simulations based on a modified Gross–Pitaevskii approach. This work provides an important transfer of basic concepts of quantum mechanics to integrated solid state devices, using quantum fluids of light.