Merged-beams study of the charge exchange between He2+ions and highly excited hydrogen atoms

Abstract

Measurements are reported of the cross section for the non-symmetric charge transfer ³He²⁺+H* to ³He⁺+H⁺ in the relative energy range 0.25 to 478 eV for excited hydrogen atoms with principal quantum numbers n ranging from 8 to 24. The experimental method involves merged beams and time-correlation analysis of the reaction products. Field ionisation is used to modify and specify the population of the excited states. The results are presented as cross sections sigma (n₁, n₂) averaged over consecutive values of n ranging from n₁ to n₂, namely sigma (8, 9), sigma (10, 14), sigma (15, 19) and sigma (20, 24). The cross sections are large, up to 10^-10 cm², and appear to be roughly independent of energy below 50 eV.