In-situ growth of gold nanostructure on glass substrates by light irradiation and their spectral properties
Substrates with gold nanoparticles aggregates adsorbed on their surfaces were prepared after irradiation of silanized glass substrates attached with gold seeds smaller than 10 nm by a fluorescent lamp,with poly(vinylpyrrolidone) as reductant and HAuCl4 as precursor.The substrates were characterized by atomic force microscopy,scanning electron microscopy,X-ray diffraction,absorption and fluorescence spectroscopy.The results showed that the multi-crystalline gold nanoparticles which finally grew up to 140 nm after 20-hour irradiation took on irregular shape,and some of them stacked to form bilayer structure.A new broad band appeared in the absorption spectra of the substrates due to the interparticle dipole-dipole coupling of surface plasmon resonance response of the gold particles,which redshifted within 600~800 nm as the particles grew up,indicating the intensification of the coupling.The substrates had an emission band centered at 405 nm in their fluorescence spectra under excitation at 223 nm,which was ascribed to radioactive recombination of the excited surface electrons with cavities in the gold particles.The fluorescence intensity shrunk as the average size of the gold particles increased.