Luminescence cross sections in the low-energy collisions of H+, H2+, and H3+ ions with H2

Abstract

Luminescence cross sections for the optical emission of molecular hydrogen in the 200–600 nm spectral range and for the atomic Balmer-β line were measured for low-energy ( ≤1 keV) H+, H2+, and H3+ ions colliding with H2 gas targets. Molecular hydrogen transitions between singlet states were observed for all the systems studied, while the emission continuum H2(a-b) and discrete spectra associated with other transitions between triplet states appeared only in the H2+ + H2 collisions, where the spin conservation rule is fulfilled. Isotopic substitutions in the H2+/D2+ + H2, D2 system show that at Elab = 1 keV, a dominant molecular luminescence mechanism is the collision-induced excitation (CIE) of the target.Graphical abstract