Franck--Condon factors in studies of dynamics of chemical reactions. IV. Nonadiabatic collisions
We investigate the application of the Franck--Condon approach to nonadiabatic molecular scattering processes. Computationally simple, analytic formulas are developed to describe the energy dependence of quenching of electronically excited atoms by atoms and molecules. These formulas include the dependence of the Franck--Condon factors on the translational wavefunctions as well as the wavefunctions for the internal degrees of freedom. We use these formulas to evaluate the translational energy dependence of the fine structure transition cross sections for F(/sup 2/P/sub 3/2/)+X..-->..F(/sup 2/P/sub 1/2/)+X, where X= Xe, H/sup +/, and H/sub 2/. The cross sections generally increase as the initial translational energy increases. Our results agree semiquantiatively (or better) with those obtained from other theoretical techniques. In the case of F+H/sup +/ we find that the absolute cross section is sensitive to the analytic form used for the nonadiabatic coupling but our model gives the correct energy dependence. At the energies of our calculations we find only a small amount of vibrational excitation of H/sub 2/. Finally, we use our expressions to interpret some trends of available experimental results on the quenching of Hg (/sup 3/P/sub 2/..-->../sup 3/P/sub 1/) by several molecules. We find that collisional excitation of the internal modes of the molecule becomes more important as the initial translational energy increases. However, these modes do not contribute to the quenching cross section in a statistical fashion.
- Research Organization:
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- OSTI ID:
- 6878462
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 68:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
FLUORINE
ATOM-ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
FRANCK-CONDON PRINCIPLE
HYDROGEN
HYDROGEN IONS 1 PLUS
XENON
CROSS SECTIONS
ELECTRONIC STRUCTURE
ENERGY-LEVEL TRANSITIONS
EXCITATION
ATOM COLLISIONS
CATIONS
CHARGED PARTICLES
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
FLUIDS
HALOGENS
HYDROGEN IONS
IONS
MOLECULE COLLISIONS
NONMETALS
RARE GASES
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena