Abstract

Fluorescence resonance energy transfer (FRET) is a technique now widely applied to probe biological and other complex systems for the determination of fluorophore separation and structure Recently Galanin’s seminal results for the residual anisotropy following resonance energy transfer have been extended beyond the Förster limit to include the radiative long-range (wave-zone) transfer¹ These results are now further extended to accommodate two-photon excitation, revealing not only novel polarisation characteristics but also a distance dependence whose analysis does not require a priori knowledge of the donor-acceptor spectral overlap.

© 1998 IEEE