Vacuum-Ultraviolet Photolysis of Ethane in Liquid-Nitrogen Solution

The photolysis of C₂H₆ in liquid nitrogen was studied at 1470 Å. It was found that the excited ethylene so produced, whose alternative paths are collisional deactivation and decomposition to acetylene plus hydrogen, was entirely deactivated by nitrogen with the acetylene quantum yield falling to zero at very low conversion: $$\begin{array}{c}{\mathrm{C}}_2{\mathrm{H}}_6^{*}\to {\mathrm{C}}_2{\mathrm{H}}_4^{†}+{\mathrm{H}}_2,\\ {\mathrm{C}}_2{\mathrm{H}}_4^{†}+\mathrm{M}\to {\mathrm{C}}_2{\mathrm{H}}_4+\mathrm{M}.\end{array}$$ The excited ethane formed in the primary process is not deactivated by 10¹² collisions per second with nitrogen. Excited ethylene formed by photolysis of ethylene at 1470 Å is not quenched by the nitrogen but is partially quenched by 0.001 mole fraction NO. Thus, electronically excited ethylene is partially deactivated by collisions at a rate of 10⁹ sec⁻¹. No positive evidence for reaction of CH₃CH with N₂ was obtained.