Theoretical investigation of fluorescence concentration quenching in two-dimensional disordered systems. Application to chlorophyll a in monolayers of dioleylphosphatidylcholine

Abstract

A master equation approach is used for investigating energy transfer and trapping in two‐dimensional disordered systems, where the traps are statistical pairs of pigment molecules closer than a critical distance R c . Fluorescence decay curves are calculated over a range of concentrations as a function of R c and the Förster transfer radius R̄0. The concentration dependence of the lifetimes is compared to the fluorescence self‐quenching data that Chauvet e t a l. obtained from real‐time measurements in monolayers of chlorophyll a and dioleylphosphatidylcholine (DOL). This dependence is found to be close to second order and for a choice of R c =10 Å the experimental data are fit if R̄0=78±2 Å. This value is in close agreement with those found in the literature from depolarization measurements.