A theoretical simulation of the 1s→2π excitation and deexcitation spectra of the NO molecule

Abstract

We present ab initio calculations for the N and O 1s→2π photoexcitation spectra and the deexcitation electron spectra which result in the decay of these core excited states. The photoexcitation spectra are simulated with potential energy curves and transition dipole moments calculated with the multiconfiguration coupled electron pair approximation method. The energy lifetime width of the core excited states, which influences the form of these excitation spectra via the broadening of the vibrational progressions, was calculated by the one center approximation. The theoretical spectra are compared to recent experimental data. The deexcitation electron spectra, which monitor the autoionization of the core excited states, are reproduced by a combination of valence configuration interaction calculations to obtain the relative energies and the one center approximation which yields decay rates to the singly charged final states. Furthermore, we included lifetime vibrational interference effects using the recently proposed moment method of Cederbaum and Tarantelli [J. Chem. Phys. 98, 9691 (1993)]. The calculated deexcitation spectra compare extremely favorably with experimental data.