Collisional Intermolecular Energy Transfer from a N2 Bath at Room Temperature to a Vibrationlly "Cold" C6F6 Molecule Using Chemical Dynamics Simulations.

Chemical dynamics simulations were performed to study collisional intermolecular energy transfer from a thermalized N2 bath at 300 K to vibrationally "cold" C6F6. The vibrational temperature of C6F6 is taken as 50 K, which corresponds to a classical vibrational energy of 2.98 kcal/mol. The temperature ratio between C6F6 and the bath is 1/6, the reciprocal of the same ratio for previous "hot" C6F6 simulations (J. Chem. Phys. 2014, 140, 194103). Simulations were also done for a C6F6 vibrational temperature of 0 K. The average energy of C6F6 versus time is well fit by a biexponential function which gives a slightly larger short time rate component, k1, but a four times smaller long time rate component, k2, compared to those obtained from the "hot" C6F6 simulations. The average energy transferred per collision depends on the difference between the average energy of C6F6 and the final C6F6 energy after equilibration with the bath, but not on the temperature ratio of C6F6 and the bath. The translational and rotational degrees of freedom of the N2 bath transfer their energies to the vibrational degrees of freedom of C6F6. The energies of the N2 vibrational mode and translational and rotational modes of C6F6 remain unchanged during the energy transfer. It is also found that the energy distribution of C6F6 broadens as energy is transferred from the bath, with an almost linear increase in the deviation of the C6F6 energies from the average C6F6 energy as the average energy of C6F6 increases.