Vibrational Energy Exchange of Highly Excited Anharmonic Oscillators

Abstract

Articles you may be interested inVibrational energy transfer from highly excited anharmonic oscillators: Quasiclassical Monte Carlo trajectory study of Br2-Ar and Br2-Br system J. Chem. Phys. 82, 4903 (1985); 10.1063/1.448662Vibrational energy transfer from highly excited anharmonic oscillators. Dependence on quantum state and interaction potentialThe probabilities of dissociation P dis, excitation P ex, de-excitation P de, and the associated average energy exchanges were calculated theoretically for a highly energized, anharmonic oscillator (12 or Brz) 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 dE. for these processes is about the same for harmonic and anharmonic oscillators and not much bigger than 1 to 2 RT. P dis increases markedly with increasing mass. The well depth (Vo) does not seem to have much effect in the range 0.004< Vo/Do<0.14, where Do is the bond dissociation energy. Exchange reactions are observed, but for shallow well depths they are rare events. From the results, it is possible to calculate A, the probability of stabilizing an atom pair by a third-body collision. This turns out to be independent of temperature but depends strongly on the mass of the third body C. It is always in the range 0.1 <A < 1.0 for the systems considered, and increases with increasing mass of C.For the dissociation process, it is found that the average dissociation event gives rise to a pair of atoms with very little excess energy (~.1O RT) above the dissociation barrier. This implies an activation energy for dissociation of the order of D o o-2RT in the Benson-Fueno theory and also a T-2 dependence for the rate of recombination of atoms.

Simplified Classical Trajectory Model of Dissociative Scattering on Surfaces: Role of Incident Vibrational and Translational Energies

“…For example, regardless of the initial phase angle of an impinging molecule, at the classical turning point in the trajectory, all molecular phase angles are strongly biased toward bond compression, 0°. This problem was identified by other authors for lower-energy gas-phase collisional studies …”

“…This surprising result required further investigation into the action of vibrational motion and its participation in CID. Given the work of Benson and Berend and Gadzuk, we explored the effect of the incident molecule's vibrational phase on the dissociation probability. The vibrational phase angle, which varies from 0 to 2π, provides a convenient measure of the internuclear separation and its conjugate momentum at any point along an anharmonic vibrational oscillation.…”

A critical review of the kinetics of the dissociation‐recombination reactions of fluorine and chlorine

“…This will reduce the values presented in Tables IV and X. They [40] also conclude that the average recombining atoms have relative translational energy much less than the RT assumed by Benson and Fueno. This implies a temperature dependence greater than T-', and they obtain TV2.…”

“…Benson and Berend [40] have shown that A, the probability of stabilizing an atom pair by a third-body collision, is nearer 0.2 than the value of unity used by Benson and Fueno. This will reduce the values presented in Tables IV and X. They [40] also conclude that the average recombining atoms have relative translational energy much less than the RT assumed by Benson and Fueno.…”

Quantum, classical and semiclassical momentum distributions: II. Morse and Coulomb potentials

“…(see also [7]). It is important to realize that because of the asymmetry of the potential the two contributions from q + > 0 and q − < 0 have different weights.…”