Gripe water as reducing and stabilizing agent for synthesis of size controlled gold nanoparticles

Green synthesis techniques are emerging as more facile and eco-friendly approach for the synthesis of metal nanoparticles compared to chemical reduction methods. Herein we report a new approach to synthesize gold nanoparticles (AuNPs) using gripe water as a reducing as well as stabilizing agent. Good control over the size of the nanoparticles from 3.2 nm to 25 nm has been achieved with this method by simply varying the experimental conditions. The Surface Plasmon Resonance bands of tunable gold nanospheres with high monodispersity and polydispersity have been obtained by this technique and monitored using UV-Visible spectrum. The morphology and the size of these AuNPs are determined using High Resolution Transmission Electron Microscope (HR-TEM). X-Ray Diffraction (XRD) analysis confirms the crystalline nature and the phase of the AuNPs. The as-synthesized AuNPs exhibit good optical nonlinearity. The nonlinear optical studies have been carried out by Z-scan technique to demonstrate its optical limiting property. The threshold limit of the AuNPs is obtained at a input intensity of 30 mW. The nonlinear refractive index of the nanoparticles is in the order of 10(-9) cm2/W and the third-order nonlinearity is estimated to be 7 x 10(-5) esu.