Experimental and theoretical study of core-valence double photoionization of OCS
2010 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 82, no 4, 043436- p.Article in journal (Refereed) Published
O 1s, C 1s, and S 2p core-valence double ionization electron spectra of the OCS molecule have been obtained experimentally by a time-of-flight photoelectron-photoelectron coincidence spectroscopy technique. In order to analyze and assign the spectral features observed, we present a protocol for computing core-valence ionization energies of such systems. The protocol is based on a restricted active space multiconfigurational self-consistent field (MCSCF) methodology with a freeze-relax procedure to guarantee a correct core-valence state root index without variational collapse. Corrections for extended dynamical correlation and core-core correlation, respectively, are made by multiconfigurational perturbation theory and by uncontracted basis set Moller-Plesset theory. Envisioning applications to larger molecules, a spin-restricted open-shell density functional method is also applied for the lowest core-valence energies. Furthermore, cross sections through a scheme for computing multiatom Auger transitions generating core-valence holes are presented. We find that the procedure outlined is capable of deriving the energy onset of core-valence ionization within a fraction of an eV and that assignments can be made of the most salient spectral features.
Place, publisher, year, edition, pages
2010. Vol. 82, no 4, 043436- p.
IdentifiersURN: urn:nbn:se:su:diva-51459DOI: 10.1103/PhysRevA.82.043436ISI: 000283536100011OAI: oai:DiVA.org:su-51459DiVA: diva2:385270
authorCount :122011-01-112011-01-102011-01-11Bibliographically approved