Resonance energy transfer from rhodamine 6G to gold nanoparticles by steady-state and time-resolved spectroscopy

In the present study, we found a pronounced effect on the PL and shortening of the overall lifetime of rhodamine 6G (R6G) when interacting with the spherical, shaped, and capped Au NPs, but there are no measured effects on radiative rate of the dye. The observed Förster distances (R0) are 105.75, 170, and 124 Å for spherical, shaped, and capped Au nanoparticles, respectively and the distances between the donor and acceptor are 103.56, 194.77, and 134.43 Å. However, the distances between the donor and acceptor are 78.26, 99.04, and 88.43 Å for spherical, shaped, and capped Au nanoparticles, respectively, using the efficiency of surface energy transfer which follows a 1/d4 distance dependence between donor and acceptor. On the basis of these findings, we may suggest that surface energy transfer process has a more reasonable agreement with experimental finding. The anisotropy decay of R6G with spherical Au nanoparticles is single exponential with correlation time constant of 240 ps. However, the anisotropy decay of R6G in shaped nanoparticles is biexponential with correlation time constants of 347 ps and 2.46 ns