Vibrational energy transfer in two-channel thermal unimolecular reactions of ethylbromide-2-dl

Abstract

The competitive thermal decomposition reaction of bromoethane-2-$d_1$ was studied in the fall-off region at three temperatures, 660.2, 693.2, 706.4 K. At each temperatures, stepsizes for He and $CF_4$ were obtained. They are 400 $cm^{-1}$ and 1200 $cm^{-1}$ for the stepladder model, respectively. For the exponential model the stepsizes of 350 $cm^{-1}$ and 1400 $cm^{-1}$ were best fitted to the experimental data. The temperature and the pressure dependence on the collision efficiency have been investigated. At the intermediate dilution it has a minimum value. The observed activation energy difference, $E_0$, between DBr and HBr elimination reactions for $CH_2DCH_2Br$ was 1.09 ± 0.01 $Kcalmole^{-1}$ at the fall-off region. The RRKM calculation was used to analyze the experimental results quantitatively.