High-energy double photoeffect and photoionization with excitation from 2 1S and 2 3S states of helium-like ions

Double ionization and ionization with excitation of helium-like ions with Z much greater than 1 from 2(1)S and 2(3)S states on the absorption of a high-frequency photon have been considered. The analytical calculation is performed in the non-relativistic photon energy range in the lowest order of perturbation theory in the inter-electron interaction. Coulomb wavefunctions and the Coulomb Green function are used as a zeroth-order approximation. Differential and total cross sections of the processes are expressed via the corresponding values for the single photoionization. The photoelectron energy spectrum is obtained in the marginal energy range (i.e. for p(1) much greater than p(2), p(1) and p(2) momenta of photoelectrons) for the double-ionization process. Simple relations between the cross sections of double ionization and ionization with excitation are derived.