Rate coefficients and integral cross-sections for the reaction of B(2PJ) atoms with acetylene

Abstract

The reactivity of B(²P_J) atoms towards C₂H₂ (C₂D₂) has been investigated using complementary experimental methods. Kinetic measurements performed with C₂H₂ over the range T = 23–295 K have yielded thermal rate coefficients which temperature dependency is well described by the following expression: k = 3.21 × 10⁻¹⁰(T/300)^−0.50exp(−37/T) cm³ molecule⁻¹ s⁻¹ in the experimental temperature range. Crossed beam experiments performed with C₂D₂ co-reagent over the range of relative translational energies E_T = 0.35–9.4 kJ mol⁻¹ have yielded integral cross sections for D(²S_1/2) production that are proportional to (E_T)^{−0.97±0.02} above 1 kJ mol⁻¹. The excellent agreement between both sets of data is discussed in terms of mechanism, invoking the presence of a very weak entrance barrier.