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THEORY ON THE RADIATIONLESS TRANSITIONS IN LARGE POLYATOMIC MOLECULES
Author(s) -
Ting ChenHanson
Publication year - 1969
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1969.tb05906.x
Subject(s) - polyatomic ion , radiative transfer , atomic physics , excitation , perturbation theory (quantum mechanics) , intersystem crossing , perturbation (astronomy) , molecule , physics , chemistry , rate equation , reaction rate constant , ground state , excited state , quantum mechanics , kinetics , singlet state
Abstract— The stationary perturbation theory of Robinson and Frosch is shown to be inadequate to describe the radiationless transitions in polyatomic molecules. An alternative theory of radiative transfer of excitation energy proposed by Franck and Sponer is considered. Evidence shows that this theory leads to a general mechanism for many radiationless transitions in semi‐isolated molecules. Empirically, the rate constants of the excitation transfer between states i and f of the same energy can be expressed by a simple equation: k t‐f =10 13 ( f i .f f ) 0.56 sec ‐1 where f 's are oscillator strengths to the ground state. This equation is accurate to within an order of magnitude for various processes, such as internal conversions and intersystem crossings with rates differing by 14 orders of magnitude. The radiative transfer is the result of second order perturbation on the molecule by the radiation field. The equation of rate constant derived from the perturbation energy agrees fairly well with the above equation.