Electron capture, loss and de-excitation in collisions involving fast metastable He+(2s) ions

Cross sections sigma 1*0 for one-electron capture by 3 He + (2s) ions in H 2 , He, N 2 , O 2 , Ar and Kr have been measured in the energy range 15-55 keV, and compared with the corresponding cross sections sigma 10 for one-electron capture by ground state He + ions. Previously measured cross sections sigma 1*2 for electron loss by He + (2s) ions have been renormalized and both electron loss and electron capture are shown to be of comparable importance in the energy range considered. Destruction of He + (2s) ions is also shown to take place to a significant extent by collisional de-excitation processes.