Enhancement of Förster energy transfer within a microspherical cavity.

Energy transfer from pyrene to perylene molecules co-doped within a poly(methyl methacrylate) latex microsphere was drastically accelerated relative to free space. Fluorescence spectra of the microspheres showed that the relative emission intensities of pyrene and perylene changed with the sphere diameter. Analyses of emission decay profiles clarified that Förster-type energy-transfer processes were induced and that the transfer rates increased within the microspherical cavity. This enhancement can be ascribed not only to the quantum electrodynamic effects on the pyrene emission rate, but also the cavity effect of increasing the overlapping factor between donor emission and acceptor absorption spectra.