Adiabatic principles in atom-diatom collisional energy transfer
This work describes the application of numerical methods to the solution of the time dependent Schroedinger equation for non-reactive atom-diatom collisions in which only one of the degrees of freedom has been removed. The basic method involves expanding the wave function in a basis set in two of the diatomic coordinates in a body-fixed frame (with respect to the triatomic complex) and defining the coefficients in that expansion as functions on a grid in the collision coordinate. The wave function is then propagated in time using a split operator method. The bulk of this work is devoted to the application of this formalism to the study of internal rotational predissociation in NeHF, in which quasibound states of the triatom predissociate through the transfer of energy from rotation of the diatom into translational energy in the atom-diatom separation coordinate. The author analyzes the computed time dependent wave functions to calculate the lifetimes for several quasibound states; these are in agreement with time independent quantum calculations using the same potential. Moreover, the time dependent behavior of the wave functions themselves sheds light on the dynamics of the predissociation processes. Finally, the partial cross sections of the products in those processes is determined with multiple exit channels. These show strong selectivity in the orbital angular momentum of the outgoing fragments, which the author explains with an adiabatic channel interpretation of the wave function's dynamics. The author also suggests that the same formalism might profitably be used to investigate the quantum dynamics of [open quotes]quasiresonant vibration-rotation transfer[close quotes], in which remarkably strong propensity rules in certain inelastic atom-diatom collision arise from classical adiabatic invariance theory.
- Research Organization:
- Colorado Univ., Boulder, CO (United States)
- OSTI ID:
- 6960952
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ATOM-MOLECULE COLLISIONS
ADIABATIC INVARIANCE
ENERGY TRANSFER
SCHROEDINGER EQUATION
HYDROFLUORIC ACID
DISSOCIATION
NEON FLUORIDES
ROTATIONAL STATES
WAVE FUNCTIONS
ATOM COLLISIONS
COLLISIONS
DIFFERENTIAL EQUATIONS
ENERGY LEVELS
EQUATIONS
EXCITED STATES
FLUORIDES
FLUORINE COMPOUNDS
FUNCTIONS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MOLECULE COLLISIONS
NEON COMPOUNDS
PARTIAL DIFFERENTIAL EQUATIONS
RARE GAS COMPOUNDS
WAVE EQUATIONS
664300* - Atomic & Molecular Physics- Collision Phenomena- (1992-)