Vibrational Energy Exchange of Highly Excited Anharmonic Oscillators

The probabilities of dissociation Pdis, excitation Pex, de-excitation Pde, and the associated average energy exchanges were calculated theoretically for a highly energized, anharmonic oscillator (I2 or Br2) colliding classically with an inert gas atom C through a Morse-type potential. The effect of varying mass and well depth was investigated. It was found that the effect of anharmonicity is to favor excitation and dissociation. However, the average ΔEv for these processes is about the same for harmonic and anharmonic oscillators and not much bigger than 1 to 2 RT. Pdis increases markedly with increasing mass. The well depth (V0) does not seem to have much effect in the range 0.004 For the dissociation process, it is found that the average dissociation event gives rise to a pair of atoms with very little excess energy (∼0.10 RT) above the dissociation barrier. This implies an activation energy for dissociation of the order of D0°—2RT in the Benson—Fueno theory and also a T—2 dependence for the rate of recombination of atoms.