Gold Nanostructures for Plasmonic Enhancement of Hyper-Raman Scattering

Abstract

Surface-enhanced hyper-Raman scattering (SEHRS) is very useful for the vibrational characterization of organic and biological molecules and their interaction with noble metal nanostructures. Many potential applications should ideally make use of gold nanostructures in order to enhance both the excitation and the weak hyper-Raman light, rather than silver nanostructures. Here, we report high SEHRS enhancement from spherical gold nanoparticles with different particle diameters ranging from 30 to 70 nm and from gold nanorods. SEHRS data of the two molecules crystal violet and rhodamine 6G obtained at an excitation wavelength of 1064 nm, absorbance spectra, and finite-difference time domain simulations of the electromagnetic field enhancement provide evidence that the SEHRS enhancement relies on the formation of nanoaggregates, with higher SEHRS signals yielded with increasing size of the nanoparticles in the aggregates. Gold nanorods and their aggregates are shown to provide optical properties that are speci...