Wavelength dependence of the photoelectron angular distributions of the rare gases

Abstract

Photoelectron angular distributions for the valence $p$ shells of the rare gases have been measured up to a photon energy of 40.8 eV (48.4 eV for Ne) using resonance radiation from a hollow-cathode discharge lamp. This work extends the range of existing absolute measurements on Ne, Kr, and Xe. Comparison with HartreeFock and RPAE (random-phase approximation with exchange) calculations indicates excellent agreement for Ne. However, the present results, particularly for Xe, add to earlier evidence that data for Ar, Kr, and Xe show systematic deviations from theory, especially at the higher photoelectron kinetic energies. For Kr and Xe, we report asymmetry parameters separately for processes leading to the ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2},\frac{1}{2}}^{}{}_{}{}^{}$ spin-orbit states of the residual ion. The Xe results indicate that ${\beta }_{\frac{3}{2}}-{\beta }_{\frac{1}{2}}$ is positive for $\lambda \ge 461$ Å, but changes sign in the range $\lambda \sim 350-400$ Å. At 304 Å, ${\beta }_{\frac{3}{2}}-{\beta }_{\frac{1}{2}}=-0.30\mathrm{}$, which agrees with a recent calculation based on the Dirac-Slater model.