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

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.