ENERGY-DEPENDENCE OF (DELTA-E)(DOWN) AND THE SHAPE OF FALLOFF CURVES - IMPLICATIONS FOR MODELING OF EXPERIMENTAL-DATA

The influence of the energy dependence of [Delta E](down) on the shape of falloff curves in unimolecular reactions is investigated using two model systems: the decomposition of C2H5 and the isomerization of cyc loheptatriene (CHT). An exponential-down model of collisional energy t ransfer is used with [Delta E](down)(E) proportional to E(i), where i = 1 for the C2H5 decomposition and i = 1/2 for the CHT isomerization. It is demonstrated that neglect of the energy dependence of [Delta E]( down) in the fitting of experimental falloff data may yield significan t discrepancies between low-pressure and high-pressure results.