FLUORESCENCE ANISOTROPY OF REVERSIBLE INTERACTING FLUOROPHORES IN SOLUTIONS - A THEORETICAL-STUDY

A model for the time-resolved fluorescence anisotropy is presented for a dilute solution containing symmetric-top molecules where rotational and translational diffusion take place simultaneously with a reversible complex formation. The description of the molecular behavior is based on a rotational diffusion model and the Smoluchowski theory of diffusion-controlled reactions. A system of differential equations for orientational probability densities was solved both numerically for the time-dependent rate constant of the complex formation and analytically under the simplifying assumption of the time-independent rate constant of the complex formation. Parametric studies of fluorescence, difference, and anisotropy decays were performed for typical values of parameters describing reorientational motion of molecules and kinetics of complex formation and dissociation.