Plasmonic near-field in the vicinity of a single gold nanoparticle investigated with fluorescence correlation spectroscopy.

We proposed the estimation of the plasmonic near-field volume in the vicinity of a single gold nanoparticle, and observed experimentally the near-field variation due to a change in the polarization of the illuminating light. Under total-internal-reflection illumination, the plasmonic near-field volume is varied by tuning the polarization of the excitation light. The variation in the optical near-field around a single gold nanoparticle was simulated theoretically with a finite-difference time domain method, and was characterized experimentally employing a fluorescence correlation spectroscopy technique. The experimental results are in agreement quantitatively with the theoretical analysis. These results are highly relevant to important efforts to clarify the interaction between the emitter and the plasmonic antenna, and should be helpful in developing a plasmonic-enhanced total-internal-reflection fluorescence imaging microscope.