Scattering of He2+ from N2; comparison of He2+ + N2 with He2+ + Ne and Ar

The scattering of He2+ ions from molecular nitrogen has been studied in the angular range 0-200 and in the energy range 200-600 eV. Elastic, simple inelastic, and single-charge-transfer scattering were observed using energy analysis of the scattered He ion to distinguish among the different processes at each observed scattering angle. The data are presented in the form of exit-channel spectra and cross section against reduced scattering angle. For scattering without electron capture, a binary collision model (in which one of the two nitrogen nuclei exchanges momentum with the projectile, the other acting as a 'spectator') is adequate up to a reduced scattering angle of approximately tau = Etheta 6000 eV deg for describing the average elastic energy transfer. Evidence for spin-selection rules in low energy ion-molecule collisions was observed. For He2+ + N2 collisions the charge-transfer processes had the largest cross section throughout the range of energies and angles, particularly at the larger value of tau. The exit-channel spectra for N2 targets are compared to those taken for Ne and Ar targets anf strong similarities are noted. Charge-transfer processes leaving the outgoing He+ in its ground state produced very high excitation of the targets (about 45 eV above the ground state for N2), showing a preference for small values of barQbar, where Q is the energy defect. (author)