  The problem of escape of a Brownian particle in a cusp-shaped metastable
potential is of special importance in nonadiabatic and weakly-adiabatic rate
theory for electron transfer (ET) reactions. Especially, for the
weakly-adiabatic reactions, the reaction follows an adiabaticity criterion in
the presence of a sharp barrier. In contrast to the non-adiabatic case, the ET
kinetics can be, however considerably influenced by the medium dynamics.
  In this paper, the problem of the escape time over a dichotomously
fluctuating cusp barrier is discussed with its relevance to the high
temperature ET reactions in condensed media.
