Abstract
The spatial distributions of photoelectrons from the photoionisation of molecular hydrogen at room temperature have been studied with the aid of synchrotron radiation from the 2.5 GeV electron synchrotron at the Physikalisch Institute, University of Bonn. Values of the asymmetry parameter beta have been determined over the photon energy range 18 to 30 eV. Using a Seya monochromator to produce plane polarised radiation monochromatised to within a bandwidth ranging from 200 to 500 mV, significant departures from beta =+2 are observed in excess of those predicted theoretically. The discrepancy is attributed to the presence of unresolved Delta N=2 rotational branches in the integrated photoelectron spectra.