Vibrational excitation in proton-hydrogen collisions at medium energies

Abstract

The vibrational populations of H2(X1 Sigma g+, nu ) produced by H+ projectiles at energies 90<or=E<or=1000 eV have been measured as a function of the scattering angle theta . A strong vibrational excitation is observed at large angles for all energies studied. Measurements of charge exchange and electronic excitation have also been performed in order to examine whether this vibrational excitation may be related to these processes. A relative increase of the charge transfer differential cross section is thus observed when the collision energy increases. A simple model is tried to rationalize the variations with E and theta of the vibrational excitation. A fairly good agreement between the experimental and theoretical results is obtained especially at low energy. The discrepancies found at higher energy may be explained in terms of interactions neglected in the model such as charge transfer and electronic excitation.