Effects of the Substituents on the Energy Flow of Toluene Derivatives in Collisions with N2 and O2

摘要

The effects of the substituents in the energy flow in four toluene derivatives (o-chloro-, o,-bromo-, oc-chloro-, and a-bromotoluene) on collision with N2 and O2 were investigated by classical trajectory methods. The energy loss by the oc-derivatives of toluene is significantly higher than that of the o-deriva-tives. Furthermore, the substituent, CI or Br, does not affect the energy loss. The dominant pathways for the vibrational decay of the excited o-derivatives are the vibration-translation (V-T) and vibration-vibration (V-V) energy transfers to N2/O2. In contrast, the vibrational relaxation of the excited oc-derivatives occurs mainly through the V-T energy transfer. The efficiency of the intermolecular V-V energy transfer of the o-derivatives is significantly higher than that of the oc-derivatives. In the o-deriva-tives, as the excited energy (ET) increases, the excited C-Hm bond frequency decreases; thus, the energy transfer via the V-V pathway increases. In the oc-derivatives, the V-V energy transfer is not efficient for both N2 and O2, although the C-H,. and N2/O2 vibrations are near resonance.