RESUMO
The effect of translational diffusion on Förster resonance energy transfer between rhodamine 6G (the donor) and malachite green (the acceptor) was investigated by examining the donor's fluorescence decay profile. Eight straight-chain alkyl alcohols were used, and the temperature of ethanol was changed to vary the viscosity; the decay profiles were analyzed using the theory developed by Gösele. The critical transfer distance obtained from the decay profile is in good agreement with that evaluated using the spectroscopic quantities, and the diffusion coefficients are consistent with the Stokes-Einstein relation. The fluorescence decay profile was described well by Gösele's theory and the effect of diffusion is clearly verified by the temperature/viscosity dependence of the diffusion constant.