Y. Dakhnovskii et al., FALSE TUNNELING AND MULTIRELAXATION TIME NONEXPONENTIAL KINETICS OF ELECTRON-TRANSFER IN POLAR GLASSES, The Journal of chemical physics, 104(5), 1996, pp. 1875-1885
Classical electron transfer in polar glasses is described by a theory
based on a model microscopic Hamiltonian which includes the discretene
ss and randomness of the glassy polar modes with distinct orientation.
When configurational dynamics is fast, the reaction is described by e
xponential kinetics with a rate constant of non-Arrhenius type. The te
mperature dependent rate constant resembles the tunneling rate, despit
e the classical transfer of the electron. This effect is called ''fals
e tunneling.'' In this limit the possibility of a self-acceleration of
the reaction is pointed out. When configurational dynamics is very sl
ow the reaction kinetics are nonexponential with multirelaxation time
behavior. The reaction is shown to be almost insensitive to temperatur
e change pointing out on a possible explanation of a broad temperature
-independent range in the ''rate constant'' in an electron transfer in
cytochrome c oxidation in chromatium. At short times, the reaction ac
celerates compared to the exponential behavior, while at long times it
becomes slower. For strongly exothermic reactions the kinetics are al
ways slower than an exponential decay. (C) 1996 American Institute of
Physics.