Theoretical study of vibrationally resolved photoionization for the C K-shell of the CO molecule

Partial photoionization cross sections and the angular asymmetry parameter β for the C K-shell of the CO molecule have been calculated in the relaxed core Hartree–Fock approximation. In contrast with all previous calculations, we introduced the relaxed core potential with a fractional charge of the ion which was fitted from the condition to get an agreement with the experimental position of the σ ∗ shape resonance for the K-shell cross section. We found the optimal value of the fractional charge to be 0.5. After performing calculations within the Born–Oppenheimer approximation for several fixed internuclear distances R, we averaged the R-dependent dipole amplitudes over R with the vibrational wavefunctions of the initial and final states. Transitions from the ground vibrational level to several vibrationally excited states of the residual molecular ion have been studied within this approximation. A good agreement was found with the recently published vibrationally resolved experimental data. 1