Enhancement of Biased Diffusion of Dye-Doped Nanoparticles by Simultaneous Irradiation with Resonance and Nonresonance Laser Beams

Abstract

We propose and demonstrate the enhancement of the biased diffusion of dye-doped nanoparticles using resonance and nonresonance laser beams. The Brownian motion of nanoparticles in a laser focus is investigated by fluorescence correlation spectroscopy (FCS) and the time variation in fluorescence intensity. From the analysis of autocorrelation functions, it is demonstrated that the difference between the transit times of nanoparticles in the focal spot with and without resonance laser irradiation increases ∼7-fold by the simultaneous irradiation of a near-infrared laser. This method is applicable to the selective optical manipulation of dye-stained nanomaterials and biomolecules in solution.