Optical trapping and alignment of single gold nanorods by using plasmon resonances

Abstract

We demonstrate three-dimensional trapping and orientation of individual Au nanorods by using laser light slightly detuned from their longitudinal plasmon mode. Detuning to the long-wavelength side of the resonance allows stable trapping for several minutes, with an exponential dependence of trapping time on laser power (consistent with a Kramer's escape process). Detuning to the short-wavelength side causes repulsion of the rods from the laser focus. Alignment of the long axis of the rods with the trapping laser polarization is observed as a suppression of rotational diffusion about the short axis.

Optical manipulation of nanoparticles: a review

“…The first experiment investigated gold nanorods with the longitudinal resonance around 800 nm [69]. Pelton et al showed repulsion of gold nanorods by a trapping laser tuned below the resonance wavelength and attraction into the trapping region for a trapping laser tuned above the resonance.…”

“…If the repetition rate of the laser is high enough, anomalies due to particle diffusion in between pulses is not significant and the forces exerted equal to their continuous wave counterparts [87]. Short pulsed lasers have also been used for visualisation of trapped nanoparticles [69]. with a laser on metal nanoparticles.…”

“…12a). The two-photon fluorescence is collected with a CCD camera and the recorded images or videos can then be further processed to analyse the particle's position and movement [69]. Another widely used method is fluorescent labelling of DNA or dielectric nanoparticles with fluorescent stains.…”

Shape-dependent plasmon resonances of gold nanoparticles

“…12 Given the advanced state of their production, most recent experimental work on gold nanorods has focused on further manipulation of their surface chemistry, [13][14][15][16][17][18][19][20][21][22][23][24] formation of complex assemblies, [25][26][27][28][29][30][31][32][33] and development of biomedical and sensing applications.…”

Shape-Dependent Oriented Trapping and Scaffolding of Plasmonic Nanoparticles by Topological Defects for Self-Assembly of Colloidal Dimers in Liquid Crystals

“…Furthermore, optical trapping of metal nanoparticles 15−18 is limited by heating, 17 the relationship between trapping and SPR wavelengths, 18 poor control of anisotropic particle orientation, and other factors. In anisotropic fluids such as liquid crystals (LCs), 19 which are of great interest for introducing tunability into the dispersions of plasmonic nanoparticles, 12,20−22 manipulation becomes even more complicated as the electric field of the trapping beam can cause local realignment and induce phase transitions in the LC host.…”