Photoelectron Spectroscopy of the Rare Gases

Abstract

A spherical retarding potential analyzer was used to measure the kinetic energies of electrons ejected by photo-ionization of the rare gases as a function of wavelength from the ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ ionization threshold down to about 400 Å. The ratio of the number of ions produced in the ground ${}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ state to the number produced in the excited ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ state was found to be constant with respect to wavelength and had the following values: 2.18, 1.98, 1.79, and 1.60 for Ne, Ar, Kr, and Xe, respectively. From these data the specific photo-ionization cross sections for the rare gases were obtained. At wavelengths shorter than the $M_1$, $N_1$, and $O_1$ thresholds for Ar, Kr, and Xe, respectively, the ejection of $s$ electrons was observed and the specific cross sections for their production measured.