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

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.