INTERPRETATION OF PRESSURE-DEPENDENT VERY-LOW-PRESSURE PYROLYSIS EXPERIMENTS

Unimolecular rate data from systems such as very‐low‐pressure pyrolysis (steady‐state flow) and static experiments where gas‐gas collisions compete with gas‐wall collisions must be interpreted in terms of reactant inhomogeneity arising from finite diffusion rates, rather than using the usual assumption of a well‐stirred reactor. An integrodifferential equation describing this process is derived, and a numerical variational solution applicable to weak gas‐gas collisions is presented. This gives a powerful method for obtaining collisional energy transfer probabilities from such experiments. Previously reported data (on cyclobutane and cycloheptatriene reactions) are reinterpreted to give conventional values for average energy transfer, replacing the anomalously low collisional efficiencies proposed previously. Copyright © 1979 John Wiley & Sons, Inc.