Quantum theory of vibrational, rotational, and translational energy exchange in collisions of polyatomic molecules. Application to methyl halides

Journal Article · Fri Apr 01 04:00:00 EST 1983 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.445343· OSTI ID:5704189

Miklavc, A

We derive a quantum theory of inter- and intramolecular transfer of vibrational, rotational, and translational energy in collisions of polyatomic molecules, in the case that short range forces between the collision partners are of prevailing importance. For this purpose, we first transform the Hamiltonian into the form which enables us to eliminate the coordinates which are cyclic in the limit of zero range forces and can thus be expected to be approximately ignorable when forces are of short, but finite, range. Instead of six rotational and three translational coordinates, we are then left with one single relevant generalized coordinate. The corresponding mass can easily be calculated; it depends on the usual reduced mass of the colliding molecules, on their moments of inertia, and on the geometry of the potential surface. The motion of the only relevant generalized coordinate is then quantized. To calculate the probabilities for the collision induced vibrational-rotational transitions, one can make use of any of a large number of the approximation schemes which have been developed in scattering theory. In the present work, we use the distorted wave expansion, for its simplicity and also because it leads, in the corresponding limit, directly to the results obtained recently by the semiclassical theory. As an application, we study vibrational deactivation probabilities of methyl halides colliding with inert gases: He, Ne, Ar, Kr, and Xe. Calculations are performed for two intermolecular potentials: exponential repulsive and Morse potential. The results obtained by the two potentials are very similar and agree well with the measured vibrational transition probabilities.

• Research Organization: Boris Kidric Institute of Chemistry, 61000 Ljubljana, Yugoslavia
• OSTI ID: 5704189
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 78:7; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
HALOGENATED ALIPHATIC HYDROCARBONS
MECHANICS
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
MOLECULES
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
POLYATOMIC MOLECULES
QUANTUM MECHANICS
ROTATIONAL STATES
VIBRATIONAL STATES