| Summary: | 碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 99 === This study is a simple approach to generate gold colloidal solution from 1 mM HAuCl4 precursor aqueous solution and the pH adjusted with NaOH. Precursor aqueous solution prepared gold colloidal solution by a short-wavelength UV-C and X-ray irradiation method at room temperature. Using two light sources to exposure solution at different times, generate gold nanoparticles morphology was observed by the transmission electron microscope(TEM).The experimental results in different HAuCl4 precursor solution pH value (pH=7.5, 11). The solution dispersion is better when pH value to increase. Because OH−concentration increased in solution, the OH− replaces the more chlorine of AuCl4−. Free radical •H and •OH are known to develop by dissociation of water molecules exposed to ionization radiation, and the more OH− in solution, OH−will be excited by the reaction of hydroxyl radical (•OH), the reduction of gold ions into gold, therefore gold particles at pH=11 the reaction rate of growth the particle surface and can quickly generate enough electrostatic repulsion to maintain the stability of dispersed particles, the formation of nano gold particles size is also smaller. In the TEM observation of nucleation growth of nano gold particles changes as precursor solution at different light source mode, the light source area of the solution is to accept a different light to stimulate the flux is also different, resulting in the initial growth of gold microstructure, showing different morphology differences. To infer growth mechanism Using observation results. Experiment add small amount of ethanol, observed that the precursor solution, add ethanol by the irradiation, effectively accelerate the growth of nano gold particle into the nuclear reaction rate, observed by TEM adding 2.5 vol% ethanol by UV irradiation 3 minutes obtain available particle size of about 30 nm spherical gold nanoparticles.
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