Angular-distribution He(I)/Ne(I) photoelectron spectra of allene

Abstract

The He(I)/Ne(I) angular distribution photoelectron spectra of allene show no change in asymmetry parameter associated with the Jahn–Teller splitting of the first band. Across the second spectral region, in contrast, there is a marked change in β-values, so confirming its assignment to overlapping second and third bands. This variation in asymmetry parameter is, however, completely different at the two ionizing wavelengths. This is attributed, unusually, to the occurrence of autoionization in the He(I)[but not Ne(I)] spectrum.