C–H bond activation was studied in low pressure microwave plasma discharges in methane. Electron energy loss channels were analyzed in view of promoting vibrational excitation. The molecular dissociative recombination (DR) channel is concluded to play multiple roles in the hydrocarbon plasma chemistry. DR increases the electron temperature with input power density and simultaneously breaks the hydrocarbon chains. Depending on the ionic species considered, plasma density $$\hbox {n}_e$$ in the range of $$10^{17}-10^{19}\,\hbox {m}^{-3}$$ ($$10^{-6}-10^{-4}$$ ionization degree) and the electron mean energy $$ $$ in the range of $$2-4\hbox { eV}$$ were estimated on basis of a Boltzman solver. $$ $$ from $$2-3\hbox { eV}$$ measured with Thomson scattering anchored the microwave discharges in a preferential regime for vibrational excitation. The best agreement with experiments was obtained when $$\hbox {C}^{+}$$ is the dominant ion in the $$\hbox {CH}_{4}$$ microwave plasma, formed through successive DR and charge exchange reactions from molecular ions.

中文翻译：

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电子-离子解离复合在 $$\hbox {CH}_{4}$$ CH 4 微波等离子体中的作用基于电子能量的模拟和测量

在甲烷中的低压微波等离子体放电中研究了 C-H 键活化。从促进振动激发的角度分析了电子能量损失通道。分子解离重组 (DR) 通道被认为在碳氢化合物等离子体化学中发挥多种作用。DR 随着输入功率密度增加电子温度，同时破坏烃链。根据所考虑的离子种类，等离子体密度 $$\hbox {n}_e$$ 在 $$10^{17}-10^{19}\,\hbox {m}^{-3}$$ ( $$10^{-6}-10^{-4}$$ 电离度）和在 $$2-4\hbox { eV}$$ 范围内的电子平均能量 $$ $$ 是基于玻尔兹曼估计的求解器。$$ $$ from $2-3\hbox { eV}$$ 用汤姆逊散射测量将微波放电锚定在振动激发的优先机制中。