Gas/gas and gas/wall average energy transfer from very low-pressure pyrolysis

Abstract

It is shown that data obtained using very low-pressure pyrolysis (VLPP) on the pressure and temperature dependence of unimolecular rate coefficients of reactants with several reaction channels yield average energies transferred in gas/gas and gas/wall collisions (the wall being seasoned quartz at 800–1200 K). The downward average energy transferred, «Δ Eå, for chlorocyclobutane/ethylene collisions is found to be 1600 cm −1 at 970 K; «Δ Eå for chlorocyclobutane/wall collisions varies from 5000 cm −1 (wall efficiency β w = 0.8) at 930 K to 3500 cm −1 (β w = 0.4) at 1150 K; similar values are found from published data on cycloheptatriene and cyclopropane- d 2. This indicates that the assumption of unit wall efficiency usually used in fitting VLPP experiments to RRKM theory needs revision.