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Kinetics of Photochemical Systems with Modulated Optical Excitation
Author(s) -
Forster M.,
Fringeli U. P.,
Günthard Hs. H.
Publication year - 1973
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19730560131
Subject(s) - chemistry , kinetics , excitation , photochemistry , classical mechanics , physics , electrical engineering , engineering
The kinetic equations of a photochemical system are discussed in which the transitions from the ground to the first excited state are produced by a sinusoidally modulated photon source. The system includes irreversible reactions starting from the first excited singlet state S 1 and the first triplet state T 1 ( cf . Fig. 1). Explicit solutions are given for a linear approximation of the equations of motion for the parametrically modulated system. The solutions apply only when there is weak optical pumping, low quantum yields of the photochemical end‐products and for certain conditions, of the modulation frequency. The concentrations of all particles occurring are shown to consist of modulated and unmodulated components where the amplitudes of the modulated components are slowly decaying exponentials. Thc phases of the modulated components are shown to be non‐decreasing along a sequence of irreversible steps. Formulae are given which permit determination of the photochemical system rate constants and location of a particle in a sequence of irreversible reactions.