Cross sections and angular distributions of the photoelectron correlation satellites of the Xe atom

Abstract

A theoretical and experimental study of the behaviour of the correlation satellites arising during 5s photoionization of xenon is presented. Many-body perturbation theory and configuration-interaction techniques have been applied to calculate the wavefunctions of the Xe II ionic states. An expression for the angular distribution parameter of the photoelectrons taking into account final-ionic-state configuration interaction is derived. Photoionization cross sections and angular distribution parameters were calculated for the 5s main line and the majority of the satellite lines and compared with our high-resolution measurements and earlier lower resolution measurements.The differences in the angular distribution parameter dependence on the photon energy for the 5s main line and satellites were analysed in terms of their origin. The most important mechanisms are: interference of several photoionization channels characterizing different orbital momenta of the photoelectron, the mixture of terms with different total orbital momenta in the final ionic state, and the dependence of the photoelectron wavefunctions on the total momentum of the photoelectrons.

Experimental and theoretical cross sections for photoionization of metastable Xe*. (6s 3 P 2, 3 P 0) atoms near threshold

“…As for the similar case of ground state Cs(6s) atoms a proper description of the photoionization dynamics of metastable Xe * atoms has to include -apart from the incorporation of the important correlation effects [18,19,[44][45][46] -relativistic effects in the calculation of the atomic orbitals (AOs).…”

High Resolution Study of Low Lying Correlation Satellites in Xenon

“…The trend from low to high photon energies, with the dominant correlations expected to change, can be seen clearly in Table I [6] show the majority of states observed with binding energy from 23-34 eV correspond to J 1͞2 and b ഠ 2, indicating a strong contribution from the 5s 21 main line. This becomes more extreme at still higher photon energies, and in the x-ray region states with J 1͞2 are exclusively observed [4].…”

“…Formation of an ionic state with one hole in its core results in a "main line" peak at a specific energy in the photoelectron spectrum, while formation of a satellite state results in a peak on the low kinetic energy side of a main line peak. The resolution with which low-lying satellite states have been observed is typically 50 meV at photon energies of 40.8 eV [5], 130 meV at energies less than 100 eV [6], and 300 meV at 1.487 keV [4]. In the region containing the lowest-lying satellite states of xenon, eight ionic states are known to exist from 23.6-24.7 eV, with some separated by an energy as small as 5 meV [7].…”

“…For comparison, the reported relative peak heights of these satellite states formed from unpolarized He II a light at 40.8 eV [5] and polarized synchrotron light at 63.5 eV [14] are shown in Table I. It should be noted that the former is not taken at the magic angle with respect to the beam (see [6] for details) and thus could show a maximum difference by a factor of 4 from the true relative cross sections of some states. Also shown are the absolute partial ionization cross sections of the satellites, calculated from our intensity data.…”

“…The CI/perturbation theory approach of Lagutin et al [6] predicts the intensity of the 5s 2 5p 4 6s 4 P 1͞2 state to be ഠ7% of the main line peak near their respective thresholds. This differs by a factor of 7 from the experimental results of both Hall et al [3] and ourselves.…”