EFFECTS OF STATIC QUENCHING AND LIGHT-PULSE INTENSITY ON THE TIME-DEPENDENT FLUORESCENCE QUENCHING KINETICS

By employing the general kinetic theory proposed recently for treating the diffusion-influenced fluorescence quenching, we investigate the n onequilibrium dynamic effect of the complex formation reaction between the ground state fluorophor and quencher molecules on the time-resolv ed fluorescence decay curve. We find that as the complex formation con stant K(eq) becomes larger the time at which the fluorescence intensit y becomes maximum shifts to a shorter time. In contrast, conventional theory predicts that the scaled fluorescence decay curve is invariant under the change in the K(eq) value. This observation suggests a possi bility of determining the magnitude of K(eq) from the time-resolved fl uorescence decay data as well as from the curvature of a Stem-Volmer c urve. We also investigate the effects of various kinetic factors such as the intensity and shape of the light pulse, the magnitude of quench er concentration, and the presence of an attractive Coulomb force or a long-range energy transfer mechanism. We find that the conventional t heory may fail in some experimental situations where repeated excitati on of fluorophor molecules is possible.