Vibration-translation energy transfer in vibrationally excited diatomic molecules
A semiclassical collision model is applied to the study of energy transfer rates between a vibrationally excited diatomic molecule and a structureless atom. The molecule is modeled as an anharmonic oscillator with a multitude of dynamically coupled vibrational states. Three main aspects in the prediction of vibrational energy transfer rates are considered. The applicability of the semiclassical model to an anharmonic oscillator is first evaluated for collinear encounters. Second, the collinear semiclassical model is applied to obtain numerical predictions of the vibrational energy transfer rate dependence on the initial vibrational state quantum number. Thermally averaged vibration-translation rate coefficients are predicted and compared with CO-He experimental values for both ground and excited initial states. The numerical model is also used as a basis for evaluating several less complete but analytic models. Third, the role of rational motion in the dynamics of vibrational energy transfer is examined. A three-dimensional semiclassical collision model is constructed with coupled rotational motion included. Energy transfer within the molecule is shown to be dominated by vibration-rotation transitions with small changes in angular momentum. The rates of vibrational energy transfer in molecules with rational frequencies that are very small in comparison to their vibrational frequency are shown to be adequately treated by the preceding collinear models.
- Research Organization:
- National Aeronautics and Space Administration, Moffett Field, CA (USA). Ames Research Center
- OSTI ID:
- 7212733
- Report Number(s):
- N-77-10877; NASA-TR-R-466; A-6453; TRN: 77-013598
- Resource Relation:
- Other Information: Thesis. Submitted to York Univ., Toronto
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ATOM-MOLECULE COLLISIONS
ENERGY TRANSFER
CARBON MONOXIDE
HELIUM
MATHEMATICAL MODELS
METASTABLE STATES
REACTION KINETICS
THREE-DIMENSIONAL CALCULATIONS
VIBRATIONAL STATES
ATOM COLLISIONS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
KINETICS
MOLECULE COLLISIONS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RARE GASES
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena