STUDY OF NON-ADIABATIC TRANSITIONS IN TRIATOMIC MOLECULES
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Date
1970
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Publisher
Ohio State University
Abstract
Non-adiabatic coupling between electronic states in triatomic molecules has been studied with special consideration of the possibility of internal conversion. Approximate calculations of electronic and vibrational coupling elements and density of states, which determine the transition probability, have been performed for $H_{2} O$ and some other molecules. The results suggest that the model mechanism for large molecules, which is of statistical type and implies an irreversible process, should not be applied to triatomics. Under favorable conditions, e.g. sufficiently different shape or position of the two potential curves involved, strong coupling might occur which is large enough to play a role in radiationless transition processes. This mechanism may explain anomalously long fluorescence lifetimes in small molecules. However, observations of lifetime $effects^{1}$ in $NO_{2}$, $SO_{2}$, and $CS_{2}$ cannot be explained with this mechanism, because internal conversion is electronically forbidden.
Description
$^{1}$A. E. Douglas, J. Chem. Physics 45, 1007 (1966).""
Author Institution: Department of Chemistry, Saint Louis University; Department of Chemistry, Illinois Institute of Technology
Author Institution: Department of Chemistry, Saint Louis University; Department of Chemistry, Illinois Institute of Technology