EXCITATION OF HELIUM BY H2+ AND H3+ (1-150-KEV)

Cross sections have been measured for excitation of helium to n1S, n1P, n1D, n3S, n3P and n3D states (n = 3, 4, 5, 6) by 1-150 keV H+2 and H+3 ions. Comparison is made with previous experiments on singlet excitation of helium by protons. In a large velocity region the excitation cross section has a similar behaviour for the three projectiles and often increases in the order of H+, H+2 and H+3. Towards lower velocities H+2 and H+3 are much more effective in excitation than H+, probably due to the possibility of exchange of electrons in the case of H+2 and H+3. In our energy region the cross section for triplet excitation is of the same order of magnitude as for singlet excitation, indicating the importance of exchange of electrons. © 1969.