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Abstract
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In this work, facile synthesis of gold nanoparticle thin films on a modified quartz substrate with UV-visible photoluminescence has been reported. The films are prepared by the centrifuge deposition of nanoparticles from a colloidal solution which has been synthesized by using the sodium citrate reduction of HAuCl4 in the water[1]. The adhesion of the gold nanoparticles on a quartz substrate is improved by oxidation with piranha solution and silanization with the 3-(trimethoxysilyl)-propylamine as shown by the atomic force microscopy (AFM)[2]. Subsequent annealing of the films at the temperatures of 600˚C for 1 hour has resulted in the pure crystalline nanogold thin layer with the localized surface plasmon resonance (SPR) peak of 522 nm. In addition, a sharp absorption peak is observed at about 242 nm (in the UV region) due to the gold nanoparticle interband transition[3]. The film scanning electron microscopy (SEM) reveals that Au nanoparticles are all sphere-shaped with an average radius range of 8-22 nm. The results of X-ray diffraction analysis (XRD) show that the films are well crystallized with the pure phases of gold. Performed X-ray photoelectron spectroscopy (XPS) analysis revealed the existence of the stable thin semi-conductive oxide layer in the phase of Au2O3 on the surface of the annealed thin films. At the applied excitation wavelength range of 220-260 nm, the films have shown a photoluminescence emission peak in the UV-Visible region at about 375 nm. This work suggests a simple pathway to fabricate nanogold thin film from colloidal samples maintaining stable optical properties for photonics and plasmonics applications[4].
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