Fluorescence quenching in the C₁₂E₆-water system: Diffusion-control in three to zero dimensions

Abstract

The quenching of fluorescence from pyrene by hexylbenzophenone in the nonionic surfactant C₁₂E₆ has been examined, both with the surfactant in neat form and with water added to produce lamellar, cubic, and hexagonal liquid crystalline phases, and the isotropic micellar solution. The efficiency of the quenching decreases in this order, due to that less quenchers are available within a certain distance from the excited state when the dimensionality is decreased. The decay curves were analysed using the appropriate models for diffusion-controlled quenching in three to one dimensions, and for quenching without exchange in small micelles. The values obtained for the mutual diffusion-coefficient of the probe-quencher pair vary between 3.5 and 6.5 × 10⁻¹¹ m² s⁻¹ in a nonsystematic way.

This is a preliminary report. A full account is planned for publication in Israel J Chem (1990)