Experimental Measurements of Dissociative Recombination in Vibrationally Excited Gases

Measurements of the temperature dependence of the dissociative recombination coefficients $\alpha$ in ${\mathrm{Ne}}_2^{+}$ and ${\mathrm{Ar}}_2^{+}$ are reported under conditions in which $T=T_i=T_e$. For both gases, the low-temperature variation of $\alpha$ was found to have an exponent of ${-0.5\mathrm{}}_{-0.1\mathrm{}}^{+0.2\mathrm{}}$, while at high temperatures the exponent was - 1.5 ± 0.1. The break between the high- and low-temperature dependencies, which occurred at 900° K for neon and at 670° K for argon, is seen to be a measure of the spacing between the ground and first vibrational levels in these molecular ions.