Multichannel quantum defect analysis of diatomic predissociation and inelastic atomic scattering
Given an N/sub T/ x N/sub T/ interaction matrix W/sup infinity/(R) which describes the dissociation of a diatomic molecule into N/sub T/ asymptotic atomic channel states, we can generate exact numerical solutions to the close-coupled scattering equations. At total energies E above the highest dissociation threshold we obtain an N/sub T/ x N/sub T/ scattering matrix S(E) which defines the asymptotic structure of the N/sub T/- fold degenerate multichannel scattering or continuum wave functions. This matrix varies rapidly with energy and is nonanalytic at thresholds. However, based on a multichannel quantum defect analysis (MCQDA) of the coupled equations we find that the numerical S(E) matrix can be made to yield a real, symmetric matrix Y(E) which is analytic in E. This matrix can then be analytically continued across threshold to provide rigorous analytic descriptions of the multichannel diatomic wave functions in the predissociating and bound-state regions of the energy spectrum. Since the extraction of Y(E) is predicated on assigning a reference potential V/sub ..gamma../(R) to each channel, the detailed energy variation of Y(E) is dependent on the choice of potentials. Fortunately, the physics contained in W/sup infinity/(R) generally dictates an obvious set of reference potentials which usually make Y(E) slowly varying. As E is reduced below threshold we can use Y(E), often well represented as a constant over a wide range of energies, to provide a description of the predissociating molecule, including such observable properties as linewidths, level shifts, and branching ratios.
- Research Organization:
- Molecular Spectroscopy Division, National Bureau of Standards, Washington, DC 20234
- OSTI ID:
- 5200707
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 80:6
- Country of Publication:
- United States
- Language:
- English
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