R. Sankari

Probing the valence character of O 1s-->Rydberg excited O2 by participator Auger decay measurements and partial ion yield spectroscopy following x-ray absorption.

The valence character of O 1s-->Rydberg excited O2 is investigated by means of participator Auger decay spectroscopy, performed at selected photon energies across the K-shell resonance region, and by means of partial ion yield x-ray absorption spectroscopy. For several of the excitation energies studied, the authors find substantial sigma*(4Sigmau-, 2Sigmau-) valence character being mixed with nssigma and npsigma (4Sigmau-, 2Sigmau-) Rydberg states. An experimental indication of a coupling between the channels associated with quartet and doublet ion cores is considered and discussed. New spectroscopic constants are derived for the singly ionized X 2Pig state of O2 based on the observation of at least 20 vibrational sublevels.

Multiple ionization of Xe—comparison of de-excitation pathways following 3d5/2 ionization and 3d5/2→ 6p resonance excitation

The partial ion yield spectra of Xen+ ions (n = 1–8) were detected by an ion time-of-flight mass analyser in the photon energy range of 664–694 eV, and the branching ratios of ions following the 3d−15/2 ionization and the 3d5/2→ 6p resonance excitation were obtained. The branching ratios were found to be almost the same. Theoretical de-excitation pathways and branching ratios of ions following the 3d5/2→ 6p resonance excitation were obtained using the single-configuration approximation and a semi-empirical model, and results were compared with the experiments and the previously published calculations for the 3d−1 ionization.

Ion production by cascade Auger transitions following the Xe 4d−1 → 6p excitation

Cascade Auger transitions following the Xe 4d → 6p excitation have been studied both experimentally and theoretically. The low kinetic energy part from 2 to 30 eV of the resonance Auger spectra has been recorded with different photon bandwidths which have enabled us to separate most of the first and second step Auger transitions from each other. The results for ion production obtained from the electron spectra are compared with the results of the partial ion yield spectra. The present theoretical results based on multiconfiguration Dirac–Fock (MCDF) approach are compared with the experimental findings and with earlier theoretical results. The discrepancies between the electron and ion data reported previously were found to originate from the difficulties in the treatment of the Auger group rates.

The Kr valence photoelectron satellite lines in the photon energy region below the 3d threshold

The photoelectron spectrum of krypton was recorded with various photon energies from 60 to 88 eV in the binding energy range of Kr 4s photoelectron line and valence satellite lines. Strong photon energy dependence was found in the experimental cross-sections of the satellite lines. The high experimental resolution of the measured spectra allowed us to really separate close lying states. This, together with the measurement of the angular anisotropy parameter β at hν = 88 eV enabled us to verify the origin of the satellite lines, i.e. whether they are created by shake-up, conjugated shake-up, or by correlation of bound or continuum states during 4s or 4p photoionization.