Electron capture and He⁺(2s) formation in fast He²⁺-H and He⁺-H collisions

Abstract

Cross sections for the accidentally resonant charge-transfer process He2++H(1s) to He+(2s)+H+ and total cross sections for the process He2++H(1s) to He+( Sigma n,l)+H+ involving capture into all final bound states of He+ have been measured for 4-343 keV 3He2+ ions. A tungsten tube furnace was used to provide a target of highly dissociated hydrogen. The results greatly extend the energy range of previous measurements and provide data of increased accuracy thereby permitting a better assessment of the range of validity of theoretical descriptions of He2+-H collisions. Corresponding cross sections for capture in H2 have also been determined. Cross sections for the direct excitation process He+(1s)+H to He+(2s)+H( Sigma ) have also been measured for the first time within the same energy range.