Abstract
Vibrationally resolved photoelectron angular distributions have been calculated for the 5 sigma photoionisation channel of CO using the multiple-scattering method. Vibrational branching ratios and vibrationally unresolved integrated cross sections and photoelectron angular distributions are also reported and compared with available measurements. Both angular distributions and branching ratios exhibit striking non-Franck-Condon behaviour caused primarily by the f-wave shape resonance in the sigma photoionisation continuum. Significant discrepancies between theory and experiment exist for the weaker vf=2,3 vibrational levels and interaction with nearby two-electron excitation is proposed as a likely cause.