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

The angular distribution of H+ fragment ions produced in 5–25 keV H+–H2 collisions was investigated in coincidence with Lyman-α photons. The observed photons arise from electron capture to the projectile H(2p) state and/or from the fragmentation of the H2 molecule via 2sσg, 2pσu or 2pΠ u states of the excited H+2* ion. An analysis of the measured angular distributions has been performed to distinguish the separate degenerate channels available to an emitted Lyman-α photon. The results show similarities to the data of Lindsay et al. (1987) who measured the non-coincident angular distribution of H+ fragment ions within the same energy range.