Analysis of differing experimental results in barrierless reactions in solution

Abstract

Different experimental techniques used to study dynamics of barrierless reactions have led to different results. An analysis of the cause of these differences is presented. In the absence of a clear separation of time scales between the reactive motion and the motion on the rest of the potential surface, different spectroscopic techniques may probe different aspects of the motion on the excited state potential surface, and may thus lead to different results for the non-radiative rate of decay of the excited state. We examine results from picosecond fluorescence, excited state absorption and ground state recovery experiments on crystal violet in normal alcohols. Excited state absorption and ground state recovery measure the non-radiative decay from the sink, whereas fluorescence decay measurements probe transient relaxation rather than the population lifetime in the excited state.