Theoretical study of processes of multiple excitation/ionization in K-photoabsorption of carbon and nitrogen in CO and N2 molecules

Spectra of multiple excitation/ionization in the region of photoabsorption K-edge of carbon and nitrogen of CO and N₂ molecules in the gas phase are studied theoretically. Processes of additional excitation/ionization from the 1π-and 5σ shells are taken into account. Single-electron wave functions in the excited state are calculated allowing for the effect of core wave functions in the field of a vacancy by the single-center method in the Hartree-Fock approximation. Cross sections for photoabsorption are calculated using the theory of nonorthogonal orbitals. The influence of many-electron correlations on the extension of the multiplet structure of certain configurations of multiple excitation is studied.