Correlation Effects in the Photoionization of Confined Calcium and Zinc

Studies of atoms confined in an endohedral environment have aroused significant recent interest [1]. In this work, the photoionization @Ca and @Zn have been studied using the Relativistic-Random-Phase Approximation, modified to include the confinement potential. Photoionization of the 4$s$ and 3$p$ subshells of free and confined atomic calcium, along with the 4$s$, 3$d$, 3$p$ and 3$s$ subshells of free and confined atomic zinc, have been studied. The photoionization parameters of confined atoms differ significantly from those of their ``free'' counterparts. The dipole cross sections and angular distribution asymmetry parameters exhibit oscillations with energy arising from the back scattering of the escaping electron by the confining potential, i.e., ``confinement resonances'' [2]. These oscillations persist when nondipole matrix elements are also included as is reflected in the nondipole cross section and angular distribution asymmetry parameters [3]; the relative strengths of the oscillations due to back-scattering in the E1 and E2 photoionization parameters have qualitatively different profiles as a function of photon energy. [1] V. K. Dolmatov, A. S. Baltenkov, J.-P. Connerade and S. T. Manson, Radiation Phys. Chem. \textbf{70}, 417 (2004). [2] M. Ya. Amusia, A. S. Baltenkov, V. K. Dolmatov, S. T. Manson and A. Z. Msezane, Phys. Rev. A \textbf{70}, 023201 (2004). [3] P.C. Deshmukh, Tanima Banerjee, K. P. Sunanda and R. Hari Varma, Radiation Phys. and Chem (submitted).