Photoionization of the Noble Gases: Cross Sections and Angular Distributions

Photoionization calculations in the noble gases Ne($L$ shell), Ar($L$ and $M$ shell), Kr($M$ and $N$ shell), and Xe($M$, $N$, and $O$ shell) using Hartree-Fock (HF) wave functions for the outgoing photoelectron are reported. Total cross sections are presented and compared with experiment. Subshell cross sections are also given and unusual features are pointed out in an effort to stimulate direct measurements of subshell cross sections via the technique of photoelectron spectroscopy. The relation between our work and the intrachannel coupling of the Fano continuum configuration-interaction theory is discussed. The asymmetry parameter $\ensuremath{\beta}$ of the angular distribution of the photoelectrons, $1+\ensuremath{\beta}$ ${P}_{2}(cos\ensuremath{\theta}$, is calculated in HF-length, HF-velocity, and Hartree-Slater (HS) approximations. The results show remarkable agreement among the $\ensuremath{\beta}'\mathrm{s}$ resulting from the several approximations despite the rather different cross sections they predict. Good agreement with recent experimental results is found and the need for further experimental work is pointed out. Extremely oscillatory behavior of the energy dependence of $\ensuremath{\beta}$ is found and the reasons for such behavior are discussed.

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