Effect of gold nanoparticle size on the linear and nonlinear optical properties

Abstract

In this paper, we investigate the linear and nonlinear (NL) optical properties of gold nanoparticles (Au-NPs) with different sizes. A colloidal gold nanoparticles solution has prepared to utilize the chemical reduction method by interacting gold chloride solution HAuCl4 with trisodium citrate solution. By using a hotplate and vigorous stirring the flask, which has the mixture solution, was heated to produce a 0.05 mg/ml of colloidal gold nanoparticles. The characterization of gold nanoparticles is executed by the utilization of different techniques. The information about nanoparticles size was achieved from the spectra measured by transmission electron microscopy (TEM). As well as the compositional characteristics are obtained using FTIR and XRD techniques. Finally, the Surface Plasmon Resonance (SPR) peaks were measured using a UV-Vis spectrophotometer. A Z-scan technique was utilized to study the nonlinear optical properties of Au nanoparticles. From the preparation of the nanoparticles, the shape of gold nanoparticles was almost spherical and has two different sizes. The nonlinear refractive index of Au nanoparticles was obtained in the order of 10-10 cm2/w extracted from a closed aperture z-scan. The nonlinear absorption of these nanoparticles was measured at 10−5 cm/w range obtained from an open aperture z-scan technique.