Vibrationally resolved photoionization of the O K-shell of CO molecule

Simultaneous theoretical and experimental study of the angular asymmetry parameter β for the O K-shell of CO molecule has been performed. Transitions from the ground vibrational level of the neutral molecule to the vibrational states of the ion with v′=0,1,2, were studied in the region of the σ∗ shape resonance. Calculations in the relaxed core Hartree-Fock approximation with a fractional charge are in a qualitative agreement with the experiment. The theory demonstrates that the dipole amplitudes with different orbital angular momentum l have different behavior with increasing v′ which explains the observed variation of β.