Dissociative recombination in krypton: Dependence of the total rate coefficient and excited-state production on electron temperature

Abstract

Microwave afterglow and grating spectrometric apparatus are used to study dissociative recombination in krypton. Over the electron temperature range $300\le T_e\le 8400$ K and with $T_{+}=T_{\mathrm{gas}}=300\mathrm{}$ K, the total rate coefficient may be represented by $\alpha \left[{{\mathrm{Kr}}_2}^{+}\right]=1.6\mathrm{}\times {10}^{-6\mathrm{}}{\left[\frac{300}{{\mathrm{T}}_e\left(\mathrm{K}\right)}\right]}^{0.55}$ ${\mathrm{cm}}^3$/sec, with an uncertainty of ± 10%. At thermal energy (300 K) excited states of Kr* having energies up to that of the ${\mathrm{Kr}}_2^{+}$ ion in its ground electronic and vibrational state are observed to result from the dissociative recombination. With microwave heating to $T_e\sim 7000$ K, additional, higher-lying Kr* states (up to ∼ 0.5 eV above the ${\mathrm{Kr}}_2^{+}$ ion ground state) are observed. In both cases the excited states most strongly populated by dissociative recombination appear to be the $5p$ states.