Two-photon excitation and ionization of the 1s shell of the argon atom

The nonrelativistic absolute values and the form of the cross section for two-photon one-electron excitation and ionization of the 1s shell of the Ar atom are calculated in the second order of the quantum-mechanical perturbation theory by taking into account both the many-body effects of relaxation of the atomic core in the fields of arising virtual vacancies and the decay of vacancies via the autoionization Auger and (or) radiative channels. The appearance of the Cooper minimum in the two-photon absorption cross section is established. The calculations are carried out for the linear and circular polarizations of photons of an incident laser beam. The calculated results may be used for predictions.