Angular distribution of hydrogen fragment ions in H+-H-2 collisions

The angular distribution of H+ fragment ions produced in 5-25 keV H+ -H-2 c ollisions was investigated in coincidence with Lyman-alpha photons. The obs erved photons arise from electron capture to the projectile H(2p) state and /or from the fragmentation of the H-2 molecule via 2s sigma(g), 2p sigma(u) or 2p pi(u) states of the excited H-2(+*) ion. An analysis of the measured angular distributions has been performed to distinguish the separate degen erate channels available to an emitted Lyman-alpha photon. The results show similarities to the data of Lindsay et al. (1987) who measured the non-coi ncident angular distribution of H+ fragment ions within the same energy ran ge.