Stimulated emission from charge-transfer reactions in the afterglow of an e-beam discharge into high-pressure helium-nitrogen mixtures

Abstract

Stimulated emission from the $B^2{\Sigma }_u^{+}$ state of ${\mathrm{N}}_2^{+}$ has been observed as a consequence of the charge‐transfer reaction between ${\mathrm{He}}_2^{+}$ and N₂ in the afterglow of a pulsed gigawatt electron beam discharge into 3 atm of helium containing 0.8 Torr nitrogen. Peak gains of the order of 0.05 cm⁻¹ were found for the (0,1) vibrational component of the ${\mathrm{B\hspace{0.17em}}}^2{\Sigma }_u^{+}{\mathrm{\to \; X\hspace{0.17em}}}^2{\Sigma }_g^{+}$ transition at 4278 Å by directly measuring the time‐resolved gain spectrum with a tunable dye laser. Correspondingly smaller gains were found for the (0,2) and (0,3) transitions of the same system at 4709 and 5228 Å, respectively.