Dissociative recombination in xenon: Variation of the total rate coefficient and excited-state production with electron temperature

A three-mode microwave afterglow apparatus has been used in conjunction with a high-speed grating spectrometer to study the variation with electron temperature of the recombination coefficient α(Xe₂⁺) and of the Xe* excited states produced by dissociative recombination over the range 300≤Tₑ≤8000 K. At low electron temperatures, 300-700 K, α(Xe₂⁺) varies approximately as Tₑ^-1/3, with a smooth transition to a ~Tₑ^-0.7 variation at higher electron temperatures, 1300-7400 K. At Tₑ=T₊=Tₙ=300 K, α(Xe₂⁺)=(2.3±0.2)×10^-6 cm³/sec, in agreement with earlier studies at room temperature. At thermal energy (300 K) Xe* excited states up to but not exceeding the energy of the Xe₂⁺ ion in its ground electronic and vibrational state are observed. With microwave heating to Tₑ~8000 K additional, higher-lying Xe* states (up to {~}0.6 eV above the Xe₂⁺ ion ground state) are produced by the dissociative recombination process.