INNER-VALENCE STATES OF CO-EV AND 46-EV STUDIED BY HIGH-RESOLUTION PHOTOELECTRON-SPECTROSCOPY AND AB-INITIO CI CALCULATIONS( BETWEEN 22)

Photoionization of the CO molecule and inner-valence states of CO+ bet ween 22 and 45 eV have been studied by means of photoelectron spectros copy using both synchrotron radiation and He II radiation. Vibrational structure has been resolved in many bands up to 45 eV. CASSCF (comple te active space self-consistent field) and MRCI (multireference config uration interaction) calculations of potential curves in the 22-30 eV range have been performed and these have been used to predict vibratio nal levels and Franck-Condon factors. In this energy range three valen ce states, D 2 Pi, 3(2) Sigma(+) and 3(2) Pi have been identified, and spectroscopic constants have been determined for the first two of the se. Above 30 eV, all valence states have been found to be repulsive. I n addition to the broad bands expected for these states, several progr essions of narrow lines are observed most probably reflecting transiti ons to Rydberg states.