Convolution analysis of the pyrene excimer formation in membranes

The mechanism of excimer formation in rigid and fluid membranes is analyzed from the fluorescence dynamics of both monomer and excimer emissions. We analyze the kinetics of the excimer emission using a convolution formalism. In the rigid state of distearyldimethylammonium chloride bilayers, we observed a discrepancy between the decay of the monomer and the excimer populations. This shows that a fraction of the pyrene probes is isolated and is not submitted to excimer formation. The convolution analysis enables us to estimate with good precision the fraction of isolated monomers. We have analyzed the monomer emission using transient diffusion models. In the rigid phase, pyrene molecules are gathered in the boundaries of the crystalline microdomains of the membrane, and the collisional quenching occurs along these defects. In the fluid state, pyrene molecules spread out over all the membrane, and the excimer formation process occurs is a two-dimensional space.