Vibrationally resolved partial cross sections and asymmetry parameters for nitrogen K-shell photoionization of the NO molecule

The vibrationally resolved partial cross sections and asymmetry parameters for the photoionization of the NO molecule producing NO⁺ N (1s ^-1) ³Π, ¹Π ions in the vibrationally excited states v′ are measured for photon energies between 412 and 419 eV, across the σ* shape resonance region above the N K-shell ionization threshold. The position of the maximum of for the N (1s^-1) is observed to move towards the N (1s^-1) ³Π and ¹Π thresholds in both channels with increasing vibrational excitation in the parent ion. The curves, on the other hand, exhibit monotonic increase in the investigated photon energy range. The major features are fairly well reproduced by ab initio vibrationally specific calculations based on the multichannel Schwinger configuration interaction (MCSCI) method for the dipole transition moments, where the effects of vibrational motion on the photoionization cross sections are included using the adiabatic approximation.