High Resolution Gas Phase Studies Of Inner-shell Excitation And Decay

High resolution {dollar}L\sb{lcub}2,3{rcub}{dollar} x-ray absorption near-edge structure of P, S and Cl compounds are reported and analyzed with the aid of SW-X{dollar}\alpha{dollar} calculations. In the post-edge region, the outgoing channels are dominated by the d channels, and the post-edge features can be understood by the interactions between the d channels and the bonding environment, such as crystal-field splitting, and centrifugal potential. The pre-edge structures are found to be influenced by the d characters mixed into the unoccupied orbitals, which are again determined by the bonding environment.;High resolution photoelectron spectra are reported for the inner valence region of {dollar}N\sb2{dollar} and CO. Vibronic couplings in the extremely complicated 30-40eV binding energy region are clearly resolved for the first time. A preliminary assignment, based on calculations which only considered the electronic excitations, is given.;High resolution photoelectron spectra are reported for the core levels of {dollar}SiH\sb4{dollar} (Si 2p), {dollar}PH\sb3{dollar} (P 2p), {dollar}GeH\sb4{dollar} (Ge 3d), and {dollar}AsH\sb4{dollar} (As 3d). Vibronic couplings are resolved for all these levels, and an analysis of the Franck-Condon factors, aided by ab initio MCSCF and Local Density Functional calculations, reveals the periodic trends for the vibrational structure.;The excitations from the Br 3d level of H Br to the continuum and the unoccupied orbitals, and the subsequent decays, are systematically analyzed. By comparison with a high resolution Br 3d photoelectron spectrum of H Br, the ligand field splitting effects are found to be dominant in the H Br Br 3d photoelectron, the MVV normal Auger, and the 3d photoabsorption spectra. In contrast, ligand field splitting is absent in the high resolution H Br Br 3d resonant Auger spectra. The resonant decay after the Br 3d {dollar}\to \sigma\sp\*{dollar} antibonding transition involves both atomic and molecular decay processes, and the competition between these two processes can be influenced by varying the photon energy and by isotope substitution. The resonant decay after the Br 3d {dollar}\to 5p\pi{dollar} Rydberg transition shows the characteristics of the Auger resonance Raman effect: the resonant Auger peak positions move linearly with the photon energy, and the lifetime broadening does not contribute to the widths of the resonant Auger peaks. Moreover, the ligand-field splitting effects are also absent from the resonant Auger spectra. These results demonstrate the exciting prospect of using resonant Auger spectroscopy for very high resolution studies on core hole decay processes, eliminating both lifetime broadening and ligand field splitting