Flash Photolysis of Methane in the Vacuum Ultraviolet. II. Absolute Rate Constants for Reactions of CH with Methane, Hydrogen, and Nitrogen

Abstract

By means of kinetic spectroscopy, the concentration of CH has been measured in the flash photolysis of methane. Measurements were made by following the attenuation of C ²Σ⁺←X ²Π Q branch at 3143 Å, where the disappearance of CH is of the first order in CH. Experiments were conducted with pure methane, methane+H₂, and methane+N₂. The reactions and the corresponding rate constants in mole⁻¹ cm³ sec⁻¹ are $$\begin{array}{cc}\mathrm{CH}+{\mathrm{CH}}_4\to {\mathrm{C}}_2{\mathrm{H}}_4+\mathrm{H},& {\text{k=1.5×10}}^{12};\\ {\mathrm{CH}}_2+{\mathrm{H}}_2\to {\mathrm{CH}}_3,& {\text{k=6.2×10}}^{11};\\ \mathrm{CH}+{\mathrm{N}}_2\to \mathrm{products},& {\text{k≃4.3×10}}^{10};\\ \mathrm{CH}+\mathrm{CH}\to {\mathrm{C}}_2{\mathrm{H}}_2,& {\text{k≃1.2×10}}^{14}.\end{array}$$