FORMATION OF H(2P) AND H(2S) IN COLLISIONS OF HE(+) WITH H-ATOMS

Cross sections for excitation of the H(2p) and H(2s) states in He+-H collisions have been determined within the energy range 2.5-25 keV amu-1. Measurements have been based on observations of both spontaneous and electric field induced Lyman alpha radiation emitted by excited H atoms in a modulated crossed beam system developed previously in this laboratory. The measurements usefully extend previous low energy measurements and allow comparison with a number of theoretical predictions. In general the theory fails to provide a satisfactory description of both the observed magnitude and strong energy dependence of the measured cross sections for this two-electron system.