Non Franck–Condon effects in the photoionization of molecular oxygen to the [formula omitted] state in the 19–31 eV photon energy region

• Published in: Chemical physics letters Vol. 333; no. 1; pp. 91 - 95
• Main Authors: Rius i Riu, Jaume, Karawajczyk, A., Stankiewicz, M., Yoshiki Franzén, K., Winiarczyk, P., Veseth, L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2001
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(00)01327-0

Photoionization to the O 2 + X 2Π g state is studied using photoelectron spectroscopy. Experimentally, vibrational branching ratios for the v=0 to 3 levels are obtained in the 19–31 eV region which show strong non Franck–Condon effects. Using ab initio many body perturbation theory branching ratios, vibrationally resolved partial cross-sections and total cross-section for ionization to the X 2Π g state are calculated. Molecular states which autoionize to the O 2 + X 2Π g state continuum are discussed. Photoionization of the O 2 π g electron is not fully explained by channel coupling effects and autoionization from known Rydberg series and valence states.