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

The angular distribution of photoelectrons from fixed-in-space molecular hy drogen has been measured in the 44-76 eV photon energy range for an ionic s tate, with a state energy of 38 eV measured from the H-2 ground state, diss ociating to H+ + H(n = 2). The photoelectrons are ejected nearly isotropica lly at 44 eV when their energy is relatively low, while ejection perpendicu lar to the molecular axis becomes more and more favoured as the photon ener gy increases. This behaviour is possibly explained in terms of direct photo ionization to the 2p pi(u), and 2s sigma(g) states of H-2(+); the former be ing favoured at 44 eV, and the latter at photon energies far from threshold .