Spectral analysis of the fluorescence quenching kinetics in micelles with probe migration

Abstract

The fluorescence quenching kinetics in monodisperse micelles considering intermicellar probe migration has been studied. Decay parameters obtained via eigenfunction expansion are correlated with the lifetime distribution and the rules of the exponential series method (ESM) applied to micellar kinetics. In a system where interacting micelles allow the excited probe to migrate between aggregates with a rate constant of the same order of that of intramicellar quenching, the principal eigenvalues will follow approximately the optimization constrain of the ESM method in which the inverse of the lifetimes is a linear function of the occupancy number j = 0, 1, 2, …. However, the normalized amplitudes of the discrete set of exponential decay terms are no longer Poisson distributed, although the model for quencher distribution in the equilibrium state is assumed to follow a Poisson law. This indicates that the distribution pattern recovered using the ESM cannot be uniquely correlated to the quencher occupancy statistics when probe migration occurs.