Direct Visualization of Wavelength-Dependent Single Dipoles Generated on Single Gold Nanourchins with Sharp Branches

Geun Wan Kim,Ji Won Ha

doi:10.1186/s11671-018-2675-2

Abstract

We present the optical properties of singe gold nanourchins (AuNUs) with sharp branches on their surfaces under dark-field (DF) microscopy and spectroscopy. The DF intensities of the single AuNUs were changed periodically as a function of the rotation angle at three localized surface plasmon resonance (LSPR) wavelengths. Furthermore, we demonstrate the generation of single dipoles with different LSPR wavelengths in multiple directions on the same AuNU surface. The multiple LSPR dipoles generated on the AuNU surface were further visualized under defocused DF microscopy and verified by characteristic doughnut-shaped defocused scattering field distributions.Graphical ᅟ

Highlights

In recent years, plasmonic gold nanoparticles with unique optical properties have been widely employed as optical sensors [1], active surface-enhanced Raman scattering (SERS) substrates [2,3,4,5,6,7], biological and chemical sensors [8,9,10], and near-infrared absorbers for photothermal therapy [11, 12]
The optical properties of single Gold nanourchin (AuNU) with sharp and short tips on their surfaces were examined by DF microscopy and spectroscopy
The DF intensities of single AuNUs were investigated with linearly polarized light at three different localized surface plasmon resonance (LSPR) wavelengths, 600 nm, 640 nm, and 700 nm, as a function of the rotation angle

Summary

Introduction

Plasmonic gold nanoparticles with unique optical properties have been widely employed as optical sensors [1], active surface-enhanced Raman scattering (SERS) substrates [2,3,4,5,6,7], biological and chemical sensors [8,9,10], and near-infrared absorbers for photothermal therapy [11, 12]. To better understand the scattering properties of single gold nanourchins (AuNUs) with sharp and short branches, the polarization-dependent dark-field (DF) scattering properties of single AuNUs were investigated at their LSPR wavelength of 700 nm [39]. We characterized the wavelengthand polarization-dependent scattering properties of single AuNUs at three different LSPR wavelengths under single-particle DF microscopy and spectroscopy.

Results

Conclusion