Experimental and theoretical studies of the

J. Chem. Phys. 101 (1994) 10429-10435
Experimental and theoretical studies of the (C ls^-1,p*)³II state of CO: Momentum transfer dependence and vibrational structure J. T. Francis

Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M, Canada N. Kosugi Institute for Molecular Science, Myodaiji, Okazaki 444, Japan A. P. Hitchcock Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1, Canada

The intensity of the X ¹S ⁺^®(C ls ^-1, p*)³II) transition of CO has been measured by electron energy loss spectroscopy using a range of scattering angles (0'-45') and impact energies (376 to 1806 eV) in order to investigate the momentum transfer dependence of a spin forbidden inner-shell excitation. A Franck-Condon factor analysis of the vibrational structure of the singlet and triplet (C ls ^-1,p*)states was used to quantify differences in the potential energy curves ofthese states. Ab initio self-consistent field configuration interaction (SCF-Cl) calculations were carried out to generate the potential curves of the ¹II and ³II (C ls ^-1,p*) states. The electronic and vibrational energies and Franck-Condon factors are in good agreement with the experimental results. The calculations indicate that the difference in the ¹II and ³II potential curves are related to differences in relaxation of both the (active)p * and other (passive) valence electrons.

Ó 1994 American Institute of Physics.