Electron transfer in thin organic films: Failure of the Born-Oppenheimer and Franck-Condon approximations, and collective phenomena

A new theoretical approach for elementary electron transfer in condensed medium has been established, in which a failure of the Born-Oppenheimer and Franck-Condon approximations, and collective phenomena of the large number of tunnel and over-barrier transitions are of paramount importance. Experimental results obtained recently on temperature T dependences of rate constant and activation energy have corroborated this approach for electron transfer in Langmuir-Blodgett film devices. In thin organic films, where tunnel luminescence and absorption of light through the mechanism of elementary electron transfer are involved, a strong linear displacement of their bands into the blue region as T increases has been predicted; the Stokes shift is temperature-independent. The bands grow exponentially in intensity as T increases. Effects of molecular aggregation have been investigated.