Excitation of hydrogen atoms by collision with helium atoms (0.3-1.5 keV)

Elastic and inelastic cross sections in H-He collisions have been measured by means of time-of-flight techniques at moderate energy (0.3-1.5 keV). The dominant inelastic process appeared to be the excitation of hydrogen. Large cross sections are found for n=2 and also for n>>3 significant excitation of the helium atom could be observed. A simple two-state quasimolecular model has been used to compute differential and total cross sections for n=2 excitation of the H atom which agrees satisfactorily with the experiments.