Association reactions of atoms and radicals

Abstract

AbstractThe pressure and temperature dependences of association reactions involving atoms and/or radicals is discussed and illustrated by reference to the reactions CH3 + CH3 → C2H6, CH3 + O2 → CH3O2, CH3 + H → CH4, and H + C2H4 → C2H5. Recent experimental measurements of the rate coefficients, k([M], T) are described, particular attention being paid to experiments designed to measure the rate coefficient over wide ranges of pressure and temperature. Methods of fitting the experimental data, to obtain estimates of the limiting rate coefficients, k0 and k∞, and to permit extrapolation to regions beyond the experimental range, are discussed. These methods include the Troe factorization technique, a combination of master equation and variational RRKM theory, and recent calculations by Wagner and Wardlaw using the technique developed by Wardlaw and Marcus to describe loose transition states.