Observation of Penning electron detachment from H− induced by metastable H*/Ng* atoms (Ng = He, Ne, Ar, Kr, Xe)

Abstract

In Penning detachment, the excess electron of an anion is detached during the anion’s collision with an electronically excited neutral species (A− + N* → A + N + e−). Penning detachment of H− has special relevance to the dynamics of stellar atmospheres and to possible technological uses. Penning detachment by excited (metastable) hydrogen and helium atoms may be the most important H− loss-step in the solar atmosphere. Here, the Penning detachment of H−/D− by collisions with H*(22S) and He*(23S/21S) excited atoms, i.e., H−/D− + H*/He* → H/D + H/He + e−, was observed for the first time via direct H−/D− anion depletion experiments. Penning detachment of H− by metastable noble gases (Ng* = He*, Ne*, Ar*, Kr*, Xe*) was observed as well, with potential applications in tokamak fusion devices being proposed.