@phdthesis{Lang2015,
  author    = {Lang, Melanie},
  title     = {Valence Shell Photoionization of Soot Precursors with Synchrotron Radiation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117038},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {A series of combustion relevant species like radicals, carbenes and polycyclic aromatic hydrocarbons were characterized in the gas phase by vacuum UV synchrotron radiation and their ionization energies (IE) and further spectroscopic details of the respective cations were retrieved from threshold photoelectron spectra. The reactive intermediates were generated by flash vacuum pyrolysis from stable precursor molecules. Furthermore three polycyclic aromatic hydrocarbons were investigated by threshold photoelectron spectroscopy, too. The experiment was performed at the VUV beamline of the Swiss Light Source in Villigen/Switzerland and the iPEPICO (imaging photoelectron photoion coincidence) setup was applied to correlate ions and electrons from the same ionization event. From the threshold photoelectron spectra and from quantum chemical computations the vibrational structure of the molecule cations and the geometry changes upon ionization were assigned. The ionization energies of the two C4H5 isomers 2-butyn-1-yl and 1-butyn-3-yl were assigned to 7.94±0.02 eV and 7.97±0.02 eV, respectively. The isomerization between the two isomers was computed to have a barrier of 2.20 eV, so a rearrangement between the two radicals cannot be excluded. From the threshold photoelectron spectra of the two constitutional C4H7 isomers 1-methylallyl and 2-methylallyl the ionization energies were assigned to 7.48±0.02 eV and to 7.59±0.02 eV for 1-E-methylallyl and 1-Z-methylallyl, as well as to 7.88±0.01 eV for 2-methylallyl. The two radicals 9-fluorenyl, C13H9, and benzhydryl, C13H11, were observed to ionize at 7.01±0.02 eV and 6.7 eV. The threshold photoelectron spectrum of benzhydryl also incorporated the signal of the diphenylmethyl carbene, C13H10, which has an IE at 6.8 eV. In addition, the head-to-head dimers of 9-fluorenyl and benzhydryl were observed as products in the pyrolysis. C26H18 has an IE at 7.69±0.04 eV and C26H22 has an IE at 8.13±0.04 eV. The three polycyclic aromatic hydrocarbon DHP (C14H16) 1-PEN (C18H22) and THCT (C22H16) were investigated in an effusive beam. The ionization energies were determined to IE(DHP)= 7.38±0.02 eV, IE(1-PEN)=7.58±0.05 eV and IE(THCT)=6.40±0.02 eV. Furthermore the thermal decomposition and the dissociative photoionization of diazomeldrum's acid was investigated. The pyrolysis products yielded beside several other products the two not yet (by photoelectron spectroscopy) characterized molecules E-formylketene, C3O2H2 and 2-diazoethenone, N2C2O. The dissociative photoionization showed the Wolff rearrangement to occur at higher internal energies.},
  subject      = {Ultraviolett-Photoelektronenspektroskopie},
  language  = {en}
}
@phdthesis{Holzmeier2015,
  author    = {Holzmeier, Fabian},
  title     = {Photoionization of Nitrogen-Containing Reactive Molecules with Synchrotron Radiation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-127763},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {The photoionization of several nitrogen-containing reactive intermediates relevant in combustion processes was investigated in the gas phase employing VUV synchrotron radiation. The intermediates were either freshly prepared and stored under cryogenic temperatures during the experiment or generated in situ by vacuum flash pyrolysis of suitable precursor molecules. The iPEPICO (imaging photoelectron photoion coincidence) setups of the VUV beamlines at the Swiss Light Source and Synchrotron SOLEIL were then used to record mass-selected threshold photoelectron (TPE) spectra. TPE spectra reveal the ionization energy and vibrational structure in the cationic states can often be resolved, which enables to distinguish different isomers. Accurate ionization energies for the radicals carbonyl amidogen, pyrrolyl, and 3-picolyl, and for the closed shell molecules isocyanic acid and cyanovinylacetylene were obtained. The analysis of the dissociative photoionization of the pyrolysis precursors enables in some cases to retrieve thermochemical data. Beyond, the absolute photoionization cross section of the cyclic carbene cyclopropenylidene was determined, NEXAFS and normal Auger spectra of isocyanic acid were recorded and analyzed at the O1s, N1s, and C1s edges, and the dissociative photoionization and pyrolysis of 1,4-di-tert-butyl-1,4-azaborinine was studied.},
  subject      = {Dissoziative Photoionisation},
  language  = {en}
}
@phdthesis{Kissner2022,
  author    = {Kißner, Katharina},
  title     = {Manipulation of electronic properties in strongly correlated Cerium-based surface alloys},
  doi       = {10.25972/OPUS-27306},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-273067},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Photoelectron spectroscopy proves as a versatile tool for investigating various aspects of the electronic structure in strongly correlated electron systems. Influencing the manifestation of strong correlation in Ce-based surface alloys is the main task of this work. It is shown, that the manifestation of the Kondo ground state is influenced by a multitude of parameters such as the choice of the metal binding partner in binary Ce compounds, the surface alloy layer thickness and accompanying variations in the lattice structure as well as the interfaces to substrate or vacuum. Gaining access to these parameters allows to directly influence essential state variables, such as the f level occupancy nf or the Kondo temperature TK. The center of this work are the intermetallic thin films of CePt5/Pt(111) and CeAgx/Ag(111). By utilizing different excitation energies, photoemission spectroscopy provides access to characteristic features of Kondo physics in the valence band, such as the Kondo resonance and its spin-orbit partner at the Fermi level, as well as the multiplet structure of the Ce 3d core levels. In this work both approaches are applied to CePt5/Pt(111) to determine nf and TK for a variety of surface alloy layer thicknesses. A temperature dependent study of the Ce 3d core levels allows to determine the systems TK for the different layer thicknesses. This leads to TK ≈200-270K in the thin layer thickness regime and TK >280K for larger layer thicknesses. These results are confirmed by fitting the Ce 3d multiplet based on the Gunnarsson-Sch{\"o}nhammer formalism for core level spectroscopy and additionally by valence band photoemission spectra of the respective Kondo resonances. The influence of varying layer thickness on the manifestation of strong correlation is subsequently studied for the surface alloy CeAgx/Ag(111). Furthermore, the heavy element Bi is added, to investigate the effects of strong spin-orbit coupling on the electronic structure of the surface alloy.},
  subject      = {Korrelation},
  language  = {en}
}
@phdthesis{Krause2009,
  author    = {Krause, Stefan},
  title     = {Determination of the transport levels in thin films of organic semiconductors},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-40470},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2009},
  abstract  = {The approach of using the combination of Ultraviolet (UPS) and Inverse Photoemission (IPS) to determine the transport levels in thin films of organic semiconductors is the scope of this work. For this matter all influences on the peak position and width in Photoelectron Spectroscopy are discussed with a special focus on organic semiconductors. Many of these influences are shown with experimental results of the investigation of diindenoperylene on Ag(111). These findings are applied to inorganic semiconductors silicon in order to establish the use of UPS and IPS on a well-understood system. Finally, the method is used to determine the transport level of several organic semiconductors (PTCDA, Alq3, CuPc, DIP, PBI-H4) and the corresponding exciton binding energies are calculated by comparison to optical absorption data.},
  subject      = {Organischer Halbleiter},
  language  = {en}
}