Strong Acceleration of Chemical Reactions Occurring Through the Effects of Rotational Excitation on Collision Geometry

Accelerating chemical reactions by rotational excitation increases both the energy available for barrier crossing and also changes the distribution of collisions with the barrier, as demonstrated herein on the gas-phase reactions O+HCl(DCl)→OH(OD)+Cl. In the picture, the dependence of the barrier energy Eb on the Jacobi angle γ is given, together with the distribution of collisions with the barrier at j=0 (▪) and 16 (▾). Such a mechanism should arise from large-amplitude oscillatory motions of molecules or reacting atomic groups. It should thus occur also in condensed phases and it should lead to nonenergetic (nonthermal) acceleration of chemical reactions by microwaves.