Photoelectron angular distributions from dissociative photoionization channels of fixed-in-space molecular hydrogen

The angular distribution of photoelectrons from fixed-in-space molecular hydrogen has been measured in the 44-76 eV photon energy range for an ionic state, with a state energy of 38 eV measured from the H 2 ground state, dissociating to H + +H( n = 2). The photoelectrons are ejected nearly isotropically at 44 eV when their energy is relatively low, while ejection perpendicular to the molecular axis becomes more and more favoured as the photon energy increases. This behaviour is possibly explained in terms of direct photoionization to the 2p u and 2s g states of H 2 + ; the former being favoured at 44 eV, and the latter at photon energies far from threshold.