| Near-edge soft x-ray photoionization spectra were measured with high resolution in energy for a series of molecules in the gas phase, using the Free University of Berlin plane-grating SX-700-II monochromator at the synchrotron radiation source BESSY. Analysis of the spectra provides details of the core-excited electronic states which are accessed, including quantum defects, natural linewidths, vibrational spacings, molecular geometries, and molecular-field splittings. The interpretation of these results characterizes the valence and Rydberg orbitals which are populated by the transitions, as well as the core orbitals which are vacated.; Photoionization spectra of carbon monoxide were measured near the carbon and oxygen K edges. Vibrational spacings and bond lengths are derived for several resonances. Results are consistent with the equivalent-core model and indicate the different influences of the carbon and oxygen 1s core holes. Corresponding spectra of H{dollar}sb2{dollar}CO and D{dollar}sb2{dollar}CO were also measured. Assignment of the complex vibrational structure in the valence-shell and Rydberg resonances is facilitated by a comparison of the spectra for the two isotopic species. Geometric and vibrational parameters are derived for several carbon 1s core-excited states. Isotopic shifts are observed in the energies and linewidths of some core-excited states.; Sulfur hexafluoride photoionization spectra, measured near the sulfur L{dollar}sb{lcub}2,3{rcub}{dollar} edges, show several series of weak, narrow Rydberg resonances. The high resolution and good counting statistics allow a complete assignment of these states. The lineshapes of the broad inner-well resonances also observed in these spectra are analyzed to establish the magnitudes of vibrational and lifetime broadening in these states.; Spectra of the H{dollar}sb2{dollar}S and D{dollar}sb2{dollar}S molecules were also measured near the sulfur L{dollar}sb{lcub}2,3{rcub}{dollar} edges. Besides lower-energy transitions to inner-well states, a complex manifold of overlapping Rydberg resonances is observed. The rich fine structure of these states arises mainly from the removal of orbital degeneracies in the molecular field. Additional structure due to vibrational excitations in the final state is identified by a comparison of the spectra for the two isotopic species. |
