Photoionization of the4d10subshell of cadmium: Photoelectron angular distributions and polarization of fluorescence radiation

Abstract

Relativistic Dirac-Fock calculations are presented for the photoelectron angular distribution asymmetry parameter $\beta$ corresponding to $4d$-subshell photoionization in Cd and for the linear polarization $P_L$ of the subsequent fluorescence radiation, for photon energies less than 185 eV. Near threshold, our results for $\beta$ lie lower than previous relativistic Dirac-Slater and nonrelativistic many-body-perturbation-theory (MBPT) calculations. The agreement with very recent measurements by Heinzmann and Schönhense is very good. Our calculations show that $P_L({}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{})=-0.059\mathrm{} \mathrm{and} -0.058\mathrm{}$ at incident photon energies $h\nu =40.2\mathrm{} \mathrm{and} 45.6$ eV, respectively. These results lie above the nonrelativistic independent-electron theory absolute maximum of -0.061 for $P_L$, but the agreement with recent measurements lying above this maximum is still not very good. Except for this peaking of $P_L({}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{})$ above the nonrelativistic theory maximum for $40.2\le h\nu \le 45.6$ eV, our results at other energies are in general agreement with the nonrelativistic MBPT calculations of Carter and Kelly. We also find that $P_L({}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{})=+0.134$ at $h\nu =21.2\mathrm{}$ eV, in excellent agreement with the experimental value of + 0.12±0.04 of Caldwell and Zare.