Excitation function for the reaction of H with C2D6

Abstract

The reaction of ‘hot’ hydrogen atoms, generated by photolysis of HI and HBr, with C₂D₆ has been examined. The integral reaction probability of the abstraction reaction H*+ C₂D₆→ HD + C₂D₅(1) has been determined at different translational energies of H* between 62 and 197 kJ mol^–1. Measurements of the moderating effect of xenon and calculated collision densities of H* in Xe have been used to examine the form of the excitation function for reaction (1) over the range 50–140 kJ mol^–1. The cross-section rises from the threshold to reach a value of (5.4 ± 1.0)× 10^–3 nm² in the range 110–140 kJ mol^–1[(0.90 ± 0.17)× 10^–3 nm² when normalised to the abstraction of a single D atom]. This is very similar to the maximum cross-section for the abstraction by H* of D from CD₃CH₂CH₂CD₃ but considerably smaller than the cross-section per D atom for the abstraction by H* of the secondary D atoms in n-C₄D₁₀.