ATOMIC AND MOLECULAR PHOTOELECTRON SPECTROSCOPY STUDIES USING SYNCHROTRON RADIATION.

摘要

Using photons from the Canadian Synchrotron Radiation Facility (CSRF) at the Tantalus electron storage ring, gas phase photoelectron spectra of the Xe 4d(,3/2,5/2) core level, and the valence orbitals of CF(,4), SiF(,4), CF(,3)I, and XeF(,2) have been obtained as a function of photon energy. Theoretical branching ratios and partial cross sections obtained from MS-X(alpha) calculations, are compared with experiment for the molecular cases. These atomic and molecular systems were studied in order to further our understanding of shape resonances and many-body effects in photoionization.;Valence orbital branching ratios for CF(,4), SiF(,4), and CF(,3)I have been obtained from 21 to (TURN)100 eV photon energy. In general, the agreement between experiment and the MS-X(alpha) results is good. In contrast to the CF(,4) results which show little structure, five shape resonances are predicted for SiF(,4) at 3, 7, 13, 23, and 35 eV kinetic energies. Similarly, two shape resonances at 15 and 17 eV kinetic energies are predicted for CF(,3)I. Although much of the behavior of CF(,3)I is very similar to CF(,4), weak shape resonances at (TURN)13 eV kinetic energy have been observed on the 3e, 2e, and 1e orbitals. Intershell correlation effects in CF(,3)I have been found to occur above the I 4d edge on the I 5p lone pair orbital (4e).;Similarly, valence orbital branching ratios have been obtained for XeF(,2) from 21 to 50 eV photon energy. A number of strong resonances are predicted and observed, in spite of the apparent lack of appropriate valence virtual orbitals and the long bond distance.;The Xe 4d(,5/2):4d(,3/2) spin-orbit branching ratio has been accurately determined from 74 to 150 eV photon energy. There is good qualitative agreement between these values and the latest relativistic random-phase approximation (RRPA) calculations of Cheng and Johnson. It is proposed that deviations in the minimum region arise from the neglect of relaxation effects during photoionization.