Angular distribution of slow photoelectrons near the threshold for double escape

Abstract

A general formula is derived for the asymmetry parameter of single photoelectrons in the energy range just above and just below the Wannier threshold. The treatment uses Herrick's SO(4) analysis of two-electron angular correlations in conjunction with the hyperspherical prediction of dominant radial correlation channels. In each of the rare gases the asymmetry parameter approaches the 'unfavoured value' beta to -1 at the double-escape threshold.