Polarized resonance Raman spectrum as a probe of nonadlabatic transitions in photodissociation: A theoretical treatment

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Abstract

The polarized resonance Raman spectrum of a two-state system (methyl iodide) is studied by use of a time-dependent formalism. The dissociation coordinate, i.e., I-CH3 stretch, is the only variable taken into consideration in our model. Potential energy curves for the relevant states are adapted from ab initio data, and the nonadiabatic coupling between them is modeled to give the correct I/I* photodissociation branching ratio. The dissociation dynamics is characterized by using one-dimensional quantum wavepackets in a diabatic electronic basis set. The anisotropy of the resonance Raman cross section, β, is calculated from these time-dependent wave functions, and it is shown that β provides a direct measure of the relative populations of the two diabatic surfaces during dissociation. Comparison with experiment shows a discrepancy which suggests that the ab initio potential energy curves may need modification.

Original languageEnglish
Pages (from-to)3091-3096
Number of pages6
JournalJournal of Physical Chemistry
Volume95
Issue number8
Publication statusPublished - 1991

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Photodissociation
photodissociation
Raman scattering
dissociation
Raman spectra
Potential energy
probes
potential energy
curves
Wave functions
iodides
Anisotropy
wave functions
formalism
anisotropy
cross sections
electronics
Experiments

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

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title = "Polarized resonance Raman spectrum as a probe of nonadlabatic transitions in photodissociation: A theoretical treatment",
abstract = "The polarized resonance Raman spectrum of a two-state system (methyl iodide) is studied by use of a time-dependent formalism. The dissociation coordinate, i.e., I-CH3 stretch, is the only variable taken into consideration in our model. Potential energy curves for the relevant states are adapted from ab initio data, and the nonadiabatic coupling between them is modeled to give the correct I/I* photodissociation branching ratio. The dissociation dynamics is characterized by using one-dimensional quantum wavepackets in a diabatic electronic basis set. The anisotropy of the resonance Raman cross section, β, is calculated from these time-dependent wave functions, and it is shown that β provides a direct measure of the relative populations of the two diabatic surfaces during dissociation. Comparison with experiment shows a discrepancy which suggests that the ab initio potential energy curves may need modification.",
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T1 - Polarized resonance Raman spectrum as a probe of nonadlabatic transitions in photodissociation

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AU - Guo, Hua

AU - Schatz, George C

PY - 1991

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N2 - The polarized resonance Raman spectrum of a two-state system (methyl iodide) is studied by use of a time-dependent formalism. The dissociation coordinate, i.e., I-CH3 stretch, is the only variable taken into consideration in our model. Potential energy curves for the relevant states are adapted from ab initio data, and the nonadiabatic coupling between them is modeled to give the correct I/I* photodissociation branching ratio. The dissociation dynamics is characterized by using one-dimensional quantum wavepackets in a diabatic electronic basis set. The anisotropy of the resonance Raman cross section, β, is calculated from these time-dependent wave functions, and it is shown that β provides a direct measure of the relative populations of the two diabatic surfaces during dissociation. Comparison with experiment shows a discrepancy which suggests that the ab initio potential energy curves may need modification.

AB - The polarized resonance Raman spectrum of a two-state system (methyl iodide) is studied by use of a time-dependent formalism. The dissociation coordinate, i.e., I-CH3 stretch, is the only variable taken into consideration in our model. Potential energy curves for the relevant states are adapted from ab initio data, and the nonadiabatic coupling between them is modeled to give the correct I/I* photodissociation branching ratio. The dissociation dynamics is characterized by using one-dimensional quantum wavepackets in a diabatic electronic basis set. The anisotropy of the resonance Raman cross section, β, is calculated from these time-dependent wave functions, and it is shown that β provides a direct measure of the relative populations of the two diabatic surfaces during dissociation. Comparison with experiment shows a discrepancy which suggests that the ab initio potential energy curves may need modification.

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