Two-photon ionization of the K-shell of a heavy beryllium-like atomic ion

Within the framework of the second order of the non-relativistic quantum perturbation theory, the analytical structure and absolute values of the generalized cross-sections of the two-photon resonant single ionization of the K-shell of heavy beryllium-like ions of titanium (Ti18+), chromium (Cr20+), iron (Fe22+) and zinc (Zn26+) atoms were predicted. The complete wave functions of the ground state of the ion and the states of its ionization are obtained in the single-configuration Hartree-Fock approximation. The effects of (a) the occurrence of giant resonances in the subthreshold region of the generalized ionization cross-sections, (b) destructive quantum interference of the probability amplitudes of radiation transitions to intermediate states of p-symmetry, and (c) the leading role of the d-symmetry of the final ionization state in determining the values of the total generalized cross-section in the region of energies of absorbed photons of the hard X-ray range were established. A scheme of the proposed experiment with linearly polarized X-ray photons is presented to verify the theoretical results obtained.