Calculation of the kinetics of the photochemical reaction of hydrogen atom transfer in a molecular crystal

Autor: M. V. Bazilevskii, V. A. Tikhomirov
Rok vydání: 2007
Předmět:
Zdroj: Russian Journal of Physical Chemistry. 81:116-128
ISSN: 1531-863X
0036-0244
DOI: 10.1134/s0036024407010220
Popis: The rate constant for the tunneling bimolecular reaction of hydrogen atom transfer in the condensed phase was calculated. For the fluorene-acridine (T1) system embedded into a fluorene molecular crystal, two-dimensional tunneling amplitudes were determined by numerically solving the Schrodinger equation and a complete calculation of the kinetic characteristics of the reaction was performed within the frame of the Fermi golden rule with consideration given to the quantization of energy levels of reactants and products and the phonon spectrum of the crystal. Sections of a PES that was calculated with regard to the interaction of the chemical subsystem with the crystalline environment were calculated by means of a previously described method. The experimentally observed kinetic characteristics were satisfactorily reproduced over a temperature range of 30 K < T < 300 K by adjusting the phonon spectrum parameters within 20% of the values obtained in their independent calculations. The proposed interpretation of the low-temperature kinetics of the process differs from that based on the earlier asymptotic estimate. The fundamental problems that arise when the Fermi golden rule is applied to the treatment of hydrogen atom transfer at low temperatures are discussed.
Databáze: OpenAIRE
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