A model for the kinetically controlled, nuclear recoil, chemical activation process is further developed to characterize the generation of excited cyclobutane and its subsequent unimolecular behavior. This approach specifically accounts for the overall effect of mixed bath gases in order to utilize previously reported pressure dependent data for cyclobutane in He, Ne, Xe, N2, and CF4. By incorporating appropriate relative energy transfer efficiencies from the activated molecule to the bath gases, a consistent interpretation for all of the experimental data is obtained. This model also provides information on the primary chemical activation process. The results indicate that ∼46% of the recoiling tritium energy is deposited into internal energy of the excited product cyclobutane-1 during the T for H replacement reaction and that the energy distribution of activated molecules is relatively independent of the bath gas present in these mixed bath gas systems. © 1978 American Institute of Physics.