Matrix effect on fluorescence lifetimes in blend like polymer particles

Abstract

Abstract Fluorescence lifetimes of colloidal dispersions of poly(methyl methacrylate) (PMMA) particles, sterically stabilized with polyisobutylene and labelled in the PMMA phase with naphthalene groups, were measured in methylcyclohexane, methanol and powder form at 77 K. The results were compared with the fluorescence lifetimes at 300 K. A Stern-Wolmer type of expression was used to interpret the results. The difference between lifetimes at 77 and 300 K is explained in terms of a matrix effect on naphthalene self-quenching N∗ + N → 2N . An empirical scheme is suggested for the mechanism.