[en] The results obtained from the nuclear recoil chemical activation of cyclobutane-t reported earlier in this laboratory have indicated that vibration to translation energy transfer is the most important collisional process for all but the most efficient energy transfer agents. Classical and semi-classical dynamical collisional models suggest that the most effective energy transfer interactions are delocalized in nature involving at least one half of the excited cyclobutane molecule. The formalism used to explore the energy transfer process also provides data which in conjunction with energy shadowing analysis is used to interpret the energetics and mechanism of the primary hot tritium reaction with cyclobutane. The hot atom reaction between nuclear recoil produced chlorine atoms and hydrogen is characterized. The steady-state non-Boltzmann theory formalism is applied to the H₂ and D₂ reaction mixtures to further explore the high energy inverse isotope effect first reported in this laboratory. A detailed study of reactions of recoil chlorine with the scavenger ethylene used in the hydrogen studies is also reported