Collisional energy transfer in polyatomic molecules: A study of anharmonicity effects in Kr+CO/sub 2/

Journal Article · Sat Dec 15 04:00:00 EST 1979 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.438336· OSTI ID:5754998

Schatz, G C; Mulloney, T

The importance of anharmonicity in determining the rates of collisional energy transfer in Kr+CO/sub 2/ is studied by combining the usual classical trajectory method with an accurate characterization of the semiclassical stationary ''states'' of the CO/sub 2/ molecules (i.e., the ''good'' action variables) before and after each collision. A linear model of the collision dynamics is assumed, which means that only energy transfer involving the symmetric and asymmetric stretch modes of CO/sub 2/ is described. Most of our studies focus upon analyzing the average changes in symmetric and asymmetric stretch good actions, and the average T..-->..V energy transfer.One can summarize these results by the statement that diagonal anharmonicity effects dominate in the high collision energy impulsive limit while off diagonal anharmonicities control energy transfer at low collision energies. We also examine the dependence of collisional energy transfer in Kr+CO/sub 2/ on the level of sophistication of the anharmonic force field, with the conclusion that (at least for the low vibrational states of CO/sub 2/), a quartic force field is necessary but apparently also sufficient to quantitatively describe the collision dynamics. In addition, the effect of initially exciting CO/sub 2/ to the states (N/sub 1/00) with N/sub 1/=0,1,2,3,8, and 16 is investigated with the conclusion that anharmonic coupling becomes increasingly important as the amount of vibrational excitation is increased, with its effect on T..-->..V energy transfer generally much smaller than that on V..-->..V transfer.

• Research Organization: Department of Chemistry, Northwestern University, Evanston, Illinois 60201
• OSTI ID: 5754998
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
ELEMENTS
ENERGY TRANSFER
KRYPTON
MOLECULE COLLISIONS
MOLECULES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
POLYATOMIC MOLECULES
RARE GASES