Dynamics of atomic photoionization: Studies with synchrotron radiation

The mechanisms that lead to states with three and four 3d vacancies following L-shell photoionization of metallic Ni have been investigated with synchrotron radiation. Vacancies were crated in all three L subshells, in the L2,3 subshells, and the L3 subshell alone, and the resultant L3-M4,5M4,5 Auger spectrum with its satellite structure was measured and analyzed. Auger diagram and satellite energies were computed in terms of a quasiatomic screening model, semiempirical shakeup and shakeoff cross sections were employed, and branching ratios were calculated from Auger transition theory with Hartree-Fock wave functions. In addition, the process which leads to the recapture of photoelectrons following near-threshold 2p photoionization of Ar has been investigated. The Russek-Mehlhorn semiclassical formalism of post-collision interaction was used to develop a theoretical model of the photoelectron recapture process. This model agrees well with the experimental data on Ar ion yields obtained with synchrotron radiation