EFFECT OF LIGHT-INTENSITY ON THE FLUORESCENCE QUENCHING KINETICS PROBED BY FREQUENCY-DOMAIN FLUOROMETRY

A theory for describing the frequency dependence of the fluorescence r esponse stimulated by a sinusoidally modulated light is developed star ting from a hierarchical system of many-body Smoluchowski equations fo r the reactant molecule distribution functions. A new aspect of the pr esent theory is that it predicts the dependence of phase angle and mod ulation on the light intensity. Under weak light intensity and at low quencher concentration, the present theory agrees with the theories pr oposed by Zhou and Szabo and by Molski and Keizer. At high quencher co ncentration, however, the discrepancy in the predicted values of phase angle and modulation is noticeable even under weak light intensity.