Theoretical calculation of the photoelectron angular distribution of neon

Abstract

The general formula of the angular distribution of photoelectron is derived by using the density matrix theory and Racah algebra method. For comparing with the experimental data, the general formula in this paper is matched to the parametric formula and the non-dipole parameters of the photoelectron angular distribution associated with the terms of the second order for both unpolarized and polarized incident light are given explicitly. From the formula of these parameters we can see that the contribution to the non-dipole parameter is from the interference between dipole amplitude and multipole amplitude. And then, the relativistic calculation program for photoelectron angular distribution is further developed with the help of the program packages GRASP2K and RATIP which are based on the multi-configuration Dirac-Fock method. By using this program, the dipole and non-dipole angular-distribution parameters for neon 2s and 2p photoelectrons are calculated concretely. The good agreement between the results of this paper and the available theoretical data is obtained in a 50-5000 eV photoelectron-energy range studied. On this basis, the angular photoelectron distributions for neon 2s and 2p are calculated with and without considering the second non-dipole terms at the photoelectron energy E=600 eV and E=5000 eV, respectively. Special attention is paid to the effects of the polarization property of incident light and the non-dipole terms of photo-electron interaction on the angular distribution of photoelectrons. The results show that 1) the dipole and non-dipole parameters of the photoelectron angular distribution are sensitive to the ionized electron orbital, it can bring out considerable diversities among the photoelectron angular distributions of the different shells; 2) non-dipole effects make the photoelectron forward distribution in the direction of incident light, the polarization property of incident light will strengthen the asymmetric distribution of photoelectrons.