Photoemission from Xe in the vicinity of the 4d Cooper minimum.

Abstract

Partial photoionization cross sections and angular-distribution asymmetry parameters have been determined for the Xe 4d and ``4p'' subshells in the photon-energy region of the 4d Cooper minimum (160 eV to 270 eV, to 520 eV for the 4d asymmetry parameter). The Cooper minimum is observed as a distinct cross-section minimum in the 4d photoionization channel. The 4d angular-distribution results are in excellent agreement with Dirac-Fock and relativistic random-phase-approximation calculations and with previous measurements. Effects of interchannel coupling are evident in the ``4p'' results. Both the partial cross section and the angular distribution for the ``4p'' photoelectron peak track the 4d cross section and angular distribution as functions of photon energy. A similar result is observed for the summed intensity and the angular distribution of the 4${d}^{\mathrm{\ensuremath{-}}1}$5${p}^{\mathrm{\ensuremath{-}}1}$np satellites of the 4d main line, which is probably due to the effects of electron correlation between the 4d and the satellite photoionization channels.