Optical study of the He+ + N2 charge transfer reaction in a flowing afterglow and in a low-pressure chamber coupled with flowing afterglow

Abstract

The He+ + N2 charge transfer (CT) reaction has been studied by optical emission spectroscopy utilizing a conventional flowing afterglow apparatus and a low-pressure apparatus. In the latter apparatus the He+ ions generated by a microwave discharge are expanded into a low-pressure chamber through a nozzle orifice. An intense structured continuum emission as well as the N2+ (C2Σ u+-X2Σg+), N 2+ (B2Σu+-X 2Σg+), and N2+ (D′ 2IIg-A2IIu) emission systems has been observed in the 190-320 nm wavelengths region in the both experiments, although the continuum emission detected in the flowing afterglow is electronically quenched and/or vibrationally relaxed by collisions with He atoms. It has been found that the N2+ (D′ 2IIg-A2IIu) emission predominates in the 210-260 nm region, and occupies about a half of that of the total emission in the 200-320 nm region. The relative excitation rate constant for the D′ state has been measured to be 30% of that of the C state, suggesting that the process leading to the D′ state is an important exit channel in the He+ + N2 CT reaction at (near) thermal energy. © 1987 American Institute of Physics.