Relating Franck-Condon blockade to redox chemistry in the single-particle picture.

In this work, we explore Franck-Condon blockade in the "redox limit," where nuclear relaxation processes occur much faster than the rate of electron transfer. To this end, the quantized rate expressions for electron transfer are recast in terms of a quantized redox density of states (DOS) within a single phonon mode model. In the high temperature regime, this single-particle picture formulation of electron transfer is shown to agree well with the semi-classical rate and DOS expressions developed by Gerischer and Hopfield. Upon incorporation into a two electrode formulation, utilizing the master equation approach, the low temperature quantized conductance features of Franck-Condon blockade are reproduced. Moreover, at sufficiently large reorganization energies, it is argued that Franck-Condon blockade should also be observable in room temperature systems. In general, this work aims to further bridge descriptions of electron transfer and transport in the single-particle picture.