@article{SchleierGerlachPratimMukhopadhyayetal.2022,
  author    = {Schleier, Domenik and Gerlach, Marius and Pratim Mukhopadhyay, Deb and Karaev, Emil and Schaffner, Dorothee and Hemberger, Patrick and Fischer, Ingo},
  title     = {Ammonia Borane, NH\(_{3}\)BH\(_{3}\): A Threshold Photoelectron-Photoion Coincidence Study of a Potential Hydrogen-Storage Material},
  series = {Chemistry-A European Journal},
  volume    = {28},
  journal   = {Chemistry-A European Journal},
  number    = {42},
  doi       = {10.1002/chem.202201378},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318895},
  year      = {2022},
  abstract  = {We have investigated the photoionization of ammonia borane (AB) and determined adiabatic ionization energy to be 9.26±0.03 eV for the X\(^{+}\) \(^{2}\)E←X \(^{1}\)A\(_{1}\) transition. Although the threshold photoelectron spectrum appears at first glance to be similar to the one of the isosteric ethane, the electronic situation differs markedly, due to different orbital energies. In addition, an appearance energy AE\(_{0K}\)-(NH\(_{3}\)BH\(_{3}\), NH\(_{3}\)BH\(_{2}\)\(^{+}\))= 10.00±0.03 eV has been determined, corresponding to the loss of a hydrogen atom at the BH\(_{3}\)-site. From the data, a 0 K bond dissociation energy for the B-H bond in the cation of 71.5±3 kJ mol\(^{-1}\) was derived, whereas the one in the neutral compound has been estimated to be 419±10 kJ mol\(^{-1}\).},
  language  = {en}
}
@article{GerlachMonningerSchleieretal.2021,
  author    = {Gerlach, Marius and Monninger, Sophie and Schleier, Domenik and Hemberger, Patrick and Goettel, James T. and Braunschweig, Holger and Fischer, Ingo},
  title     = {Photoelectron Photoion Coincidence Spectroscopy of NCl\(_{3}\) and NCl\(_{2}\)},
  series = {ChemPhysChem},
  volume    = {22},
  journal   = {ChemPhysChem},
  number    = {21},
  doi       = {10.1002/cphc.202100537},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257322},
  pages     = {2164-2167},
  year      = {2021},
  abstract  = {We investigate NCl\(_{3}\) and the NCl\(_{2}\) radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl\(_{3}\) is broad and unstructured due to the large geometry change. An ionization energy of 9.7±0.1 eV is estimated from the spectrum and supported by computations. NCl2 is generated by photolysis at 213 nm from NCl\(_{3}\) and its ms-TPES shows an extended vibrational progression with a 90 meV spacing that is assigned to the symmetric N-Cl stretching mode in the cation. An adiabatic ionization energy of 9.94 ± 0.02 eV is determined.},
  language  = {en}
}
@article{ReuschHolzmeierGerlachetal.2019,
  author    = {Reusch, Engelbert and Holzmeier, Fabian and Gerlach, Marius and Fischer, Ingo and Hemberger, Patrick},
  title     = {Decomposition of Picolyl Radicals at High Temperature: A Mass Selective Threshold Photoelectron Spectroscopy Study},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  number    = {72},
  doi       = {10.1002/chem.201903937},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208132},
  pages     = {16652-16659},
  year      = {2019},
  abstract  = {The reaction products of the picolyl radicals at high temperature were characterized by mass-selective threshold photoelectron spectroscopy in the gas phase. Aminomethylpyridines were pyrolyzed to initially produce picolyl radicals (m /z =92). At higher temperatures further thermal reaction products are generated in the pyrolysis reactor. All compounds were identified by mass-selected threshold photoelectron spectroscopy and several hitherto unexplored reactive molecules were characterized. The mechanism for several dissociation pathways was outlined in computations. The spectrum of m /z =91, resulting from hydrogen loss of picolyl, shows four isomers, two ethynyl pyrroles with adiabatic ionization energies (IE\(_{ad}\)) of 7.99 eV (2-ethynyl-1H -pyrrole) and 8.12 eV (3-ethynyl-1H -pyrrole), and two cyclopentadiene carbonitriles with IE′s of 9.14 eV (cyclopenta-1,3-diene-1-carbonitrile) and 9.25 eV (cyclopenta-1,4-diene-1-carbonitrile). A second consecutive hydrogen loss forms the cyanocyclopentadienyl radical with IE′s of 9.07 eV (T\(_0\)) and 9.21 eV (S\(_1\)). This compound dissociates further to acetylene and the cyanopropynyl radical (IE=9.35 eV). Furthermore, the cyclopentadienyl radical, penta-1,3-diyne, cyclopentadiene and propargyl were identified in the spectra. Computations indicate that dissociation of picolyl proceeds initially via a resonance-stabilized seven-membered ring.},
  language  = {en}
}
@phdthesis{Falge2012,
  author    = {Falge, Mirjam},
  title     = {Dynamik gekoppelter Elektronen-Kern-Systeme in Laserfeldern},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-72889},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Die vorliegende Arbeit besch{\"a}ftigt sich mit der theoretischen Untersuchung zweier Themenkomplexe: der Erzeugung Hoher Harmonischer in Molek{\"u}len und dem Einfluss von gekoppelter Elektronen-Kern-Dynamik auf Ultrakurzpuls-Ionisationsprozesse und Quantenkontrolle. W{\"a}hrend bei der Untersuchung der Hohen Harmonischen die Auswirkungen der Kernbewegung auf die Spektren im Mittelpunkt des Interesses stehen, wird bei der Analyse der gekoppelter Elektronen-Kern-Dynamik das Hauptaugenmerk auf die nicht-adiabatischen Effekte gerichtet, die auftreten, wenn Kern- und Elektronenbewegung sich nicht, wie es im Rahmen der Born-Oppenheimer-N{\"a}herung in der Quantenchemie h{\"a}ufig angenommen wird, voneinander trennen lassen.},
  subject      = {Nichtadiabatischer Prozess},
  language  = {de}
}
@phdthesis{Bradeanu2005,
  author    = {Bradeanu, Ioana Lavinia},
  title     = {Photoionization and excitation of free variable size van der Waals clusters in the inner shell regime},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-16372},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {The studies presented in this thesis deal with resonant and non-resonant excitation of free variable size clusters using synchrotron radiation in the soft X-ray regime. The post collision interaction (PCI) effect is investigated in free variable size krypton and argon clusters near the Kr 3d and Ar 2p ionization energies. The core ionization energies of surface and bulk sites in variable size clusters can be clearly distinguished. This is mostly due to the polarization screening. It is found that the asymmetry, which is a consequence of PCI, is characteristically smaller for clusters than for isolated atoms. Moreover, there is less asymmetry for bulk sites than for surface sites in variable size rare gas clusters. We assign the results in terms of mechanisms that are based on quantum mechanical models of post collision interaction. Complementary experiments on the photoionization of free van der Waals clusters are performed by using zero kinetic energy (ZEKE) photoelectron spectroscopy in the Ar 2p-, Kr 3d-, Ne 1s-, and N2-regimes. The experimental approach is also suitable to detect cluster size dependent changes in electronic structure. This also allows us to study post collision interaction in variable size clusters. The parameters of the PCI profiles deduced for ZEKE experiments indicate that there are no significant changes in core ionization dynamics compared to near-threshold experiments. Results from model calculations in Kr 3d ionization energy indicate that different geometric sites can be clearly distinguished from each other by their substantial shift in Kr 3d ionization energy, though the dimer shows almost the same Kr 3d ionization energy as the free atom. A comparison with the experimental results indicates that there is resemblance with the model calculations, even though close-lying ionization energies are blended and require deconvolutions of the experimental spectra. It is evident from the present work that one can observe distinct shifts in core ionization energies in van der Waals clusters that are formed in wide size distributions of a jet expansion. The emission of ultraviolet fluorescence radiation from variable size argon clusters is investigated with high spectral resolution in the Ar 2p-excitation regime. The fluorescence excitation spectra reveal strong fluorescence intensity in the Ar 2p-continuum, but no evidence for the occurrence of discrete low-lying core-exciton states in the near-edge regime. This finding is different from the absorption and photoionization cross sections of argon clusters and the solid. The dispersed fluorescence shows a broad molecular band centered near 280 nm. The present results are consistent with the formation of singly charged, excited moieties within the clusters, which are assigned as sources of the radiative relaxation in the 280 nm regime. A fast energy transfer process (interatomic Coulombic decay, ICD) is assigned to be primarily the origin of these singly charged, excited cations besides intra-cluster electron impact ionization by Auger electrons. Our findings give possibly the first experimental evidence for ICD in the core level regime. Free, variable size nitrogen clusters are investigated in the N 1s excitation regime in comparison with the free molecule and solid nitrogen. The conversion of Rydberg states into core excitons, surface and bulk, was studied. The experimental results are simulated by ab initio calculations using (N2)13 as a reasonable prototype cluster structure that allows us to simulate both surface and bulk properties in comparison with the isolated molecule. The present results clearly show that there are specific properties, such as molecular orientation, in molecular van der Waals clusters, which do not exist in atomic van der Waals clusters. It is shown that inner and outer surface sites give rise to distinct energy shifts of the low lying surface core excitons.},
  subject      = {Photoionisation},
  language  = {en}
}