ARE ANOMALIES IN THE KINETICS OF HALOGENATION CAUSED BY HOT ATOM EFFECTS - AN EXPERIMENTAL INVESTIGATION

It has been recently proposed that observed anomalies in the kinetic data base for the reaction of Cl with C2D6 may be explained by the formation of hot Cl atoms in the reactions C2H5+Cl2-->C2H5Cl+Cl and C2D5+Cl2-->C2D5Cl+Cl. We have performed a competitive kinetic study in which the loss of C2H5 and C2D6 were monitored following UV irradiation of C2H6-C2D6-Cl2-N2 mixtures. A large excess of N2 diluent was used to ensure rapid thermalization of any hot Cl atoms formed in the system. Our measured value of k(Cl+C2D6)/k(Cl+C2H6)=0.325+/-0.020 is in agreement with results from previous relative rate studies in which no added N2 was used. This agreement shows that hot atom effects do not explain the anomalies in the literature values for the rate of the reaction Cl+C2D6.