Abstract— Metal nanoshells consists of a dielectric core surrounded by a thin noble metal shell, possess unique optical properties, including a strong optical absorbance that can be selectively tuned to any wavelength across the visible and infrared regions of the spectrum simply by adjusting the ratio of the dielectric core to the thickness of the metal overlayer[1].These features render nanoshells attractive for use in technologies ranging from conducting polymer devices to biosensing, drug delivery and photothermal therapy by absorbing light in NIR range in which human body has the most transparency[2,3]. This paper reports a systematic investigation of the characterization and growth of small gold nanoparticles on the functionalized surface of larger silica nanoparticles. monodispersed silica particles and gold nanoparticles were prepared by sol–gel method. The size of the particle could be altered by repeating the stage of reducing HAuCl4 on Au/APTES/silica particles, and the time for which they react. The nanocoreshell particles prepared were studied using scanning electron microscopy(TEM), UV–vis spectroscopy, Fourier transform infrared spectroscopy(FTIR) and PL spectrophotometer(figures. 1-4). It shows that By growing gold nanoseeds over the silica cores a red shift in the maximum absorbance of UV-Visible spectroscopy is observed. furthermore, a remarkable intensification happens in the PL spectra of silica@Au NPs compered with that of bare silica nanoparticles but,the existance of gold nanoseeds on the silica particles surface does not change the peaks of these nanoparticles

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