An adiabatic model for the photodissociation of CH{sub 3}SH in the first ultraviolet absorption band
- Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)
The photodissociation of CH{sub 3}SH in the first absorption band is studied via {ital ab} {ital initio} computation of the relevant potential energy surfaces and exact quantum scattering calculations. The effective valence shell Hamiltonian ({ital H}{sup {nu}}) {ital ab} {ital initio} many-body perturbation technique is used to calculate the global ground {ital X} {sup 1}{ital A}{prime} and 1 {sup 1}{ital A}{double_prime} surfaces as functions of the C--S and S--H internuclear distances. The finite range scattering wave function (FRSW) time-independent quantum scattering method is used to compute the adiabatic dynamics of S--H and C--S bond fission on the 1 {sup 1}{ital A}{double_prime} surface following excitation. Two calculations are performed, one in which the ground state is represented by a cubic spline function fitted to the {ital ab} {ital initio} data and another in which it is represented as the sum of two uncoupled Morse oscillators. Absorption spectra as well as the branching ratios and photofragment translational energy distributions corresponding to various excitation energies are presented and compared to recent experimental results. A final calculation examines how the branching ratio and product vibrational state distribution changes for the photodissociation of a CH{sub 3}SH molecule with one quantum of vibrational excitation in the C--S stretch.
- DOE Contract Number:
- FG02-92ER14305; FG02-87ER13679
- OSTI ID:
- 57914
- Journal Information:
- Journal of Chemical Physics, Vol. 102, Issue 18; Other Information: PBD: 8 May 1995
- Country of Publication:
- United States
- Language:
- English
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