Quenching of fluorescence by irreversible energy transfer at arbitrary strong pumping light

Abstract

The irreversible inter-molecular energy transfer in solutions, acting as a mechanism of fluorescence quenching, is studied at an arbitrary strength of the pumping light. Using powerful methods of an original Integral Encounter Theory, we prove that the fluorescent quantum yield obeys the generalized Stern–Volmer law, linear in concentration of the unexcited energy acceptors. In contact approximation we specify how this fraction depends on the total concentration of acceptors at different lifetimes of excitations and an arbitrary excitation rate. The Stern–Volmer constant which is a function of the same parameters, either increases or decreases with light intensity depending on how fast is the decay of excited acceptor. These non-linear effects provide additional information about the energy exchange mechanism and its parameters.