Reactions of Hot (n, γ)-Produced 80Br with CH3Br. Comparison with the Reactions between Hot 38Cl and CH3Cl, and Calculation of the Excitation Functions

The reactions of hot (n, γ)‐produced 17.6 m ⁸⁰Br with methyl bromide were studied in the presence of He and Kr as moderators. The survival probability of the reaction products was found to be the same in both moderators, suggesting that no observable decomposition took place upon moderation (within a 15% error). The reactivity integral for halogen displacement in the reaction was found to be equal to that in the system ${}^{38}\mathrm{Cl}+{\mathrm{CH}}_3\mathrm{Cl},$ which seems reasonable since the activation energies and steric factors are almost equal. The ratio of hydrogen displacement to halogen displacement was smaller in the case of ⁸⁰Br than in that of ³⁸Cl, as can be predicted on the basis of the translational inertial factor. From the reactivity integrals and the activation energies the excitation functions for halogen displacement were calculated by the energy‐dependent hard potential model of Baer and Amiel.