The Arrhenius Parameters for the Reactions of N(24S3⁄2) with Halogen Molecules

The temperature dependence of the rate constants for the reactions of ground-state atomic nitrogen with halogens were measured by means of a pulse radiolysis-resonance absorption technique. The rate constants for iodine and bromine were well expressed by the following Arrhenius expressions below 410 K: k(N+I2)=1.1×106 exp(−1170/T); k(N+Br2)=1.1×105 exp(−1490/T), in units of m3 mol−1 s−1. The rate constant for the reaction with chlorine was found to be 1.1×103 m3 mol−1 s−1 at 411 K. Below this temperature, the rate constants for N+Cl2 were too small to be measured. The preexponential factors for the I2 and Br2 reactions were found to be much smaller than the semiempirically calculated ones. These small preexponential factors suggest that the reactions between N(4S) and halogens proceed via nonadiabatic routes.