Dependence of the structural optical and thermo-physical properties of gold nano-particles synthesized by laser ablation method on the nature of laser

This current project is dedicated to a fast, easy and one step method for the synthesis of gold nano-particles. Gold (Au) nano-particles have been fabricated by laser ablation method in de-ionized water. The purpose was to explore the dependence of the various properties of the gold nano particles on the nature of laser. In order to prepare colloidal solutions, a low power continuous wave (CW) diode laser and a nanosecond pulsed Nd:YAG laser have been used to ablate the gold target. The structural, physical, optical and thermal characteristics of prepared nano-particles have been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), UV-vis spectroscopy and thermal conductivity of liquids and gases unit (TCLGU), respectively. The XRD analyses revealed the formation of polycrystalline gold nano-particles with (111), (200) and (220) plans in case of both the lasers. AFM micrographs showed that prepared nano-particles are spherical in dimensions. The size of nanoparticles synthesized by CW laser ranges from 5 to 20 nm whereas the size ranges from 12 to 49 nm in case of pulsed laser. UV-vis spectroscopy showed surface plasmon resonance (SPR) peak at 512 nm for CW laser prepared nanoparticles as compared to pulsed laser at 525 nm which is also indicative of the smaller size in case of CW laser. The thermal conductivity of colloidal solution prepared by CW laser is 33% whereas in case of pulsed laser is 48% more as compared to the deionized water (base liquid).