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Effect of irradiation time in the synthesis of Au-Ag nanoalloys by femtosecond laser
摘要： The synthesis of metallic nanoparticles can be performed by femtosecond laser-induced photoreduction of the metallic ion solution. Due to hydrogen radical and the solvated electron generated through the interaction of ultrafast laser and water medium, the dissolved metallic ion in the medium can be converted to their respective metallic atom and then precipitated into nanoparticles. When there is more than one metallic ion available in the solution, alloy nanoparticles can be generated. One parameter that affects this laser-based synthesis was the duration of laser irradiation time that has an advantage for size modification of nanoparticles. In this work, we have synthesized Au-Ag nanoalloys from the mixture of Au and Ag ion in water medium added with 0.01wt% polyvinylpyrrolidone (PVP) as a capping agent and irradiated for 5 and 10 minutes. The result showed that there was linear shifting in surface plasmon resonance (SPR) of the nanoalloys in respect with their volume fraction of the ions. The results also revealed that the nanoparticle size was indeed reduced as the laser irradiation was prolonged, i.e., Au50Ag50 has a particle size of 7.98 nm and 5.18 nm for 5 and 10 minutes irradiation time, respectively.
关键词： irradiation time,Au-Ag nanoalloys,surface plasmon resonance,femtosecond laser,nanoparticle size
更新于2025-09-23 15:19:57
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Carbon coated TiO2 nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2
摘要： We report on the synthesis of TiO2 nanoparticles using nanosecond pulse laser ablation of titanium in liquid, gaseous and supercritical CO2. The produced particles were observed to be mainly anatase-TiO2 with some rutile-TiO2. In addition, the particles were covered by a carbon layer. Raman and X-ray diffraction data suggested that the rutile content increases with CO2 pressure. The nanoparticle size decreased and size distribution became narrower with the increase in CO2 pressure and temperature, however the variation trend was different for CO2 pressure compared to temperature. Pulsed laser ablation in pressurized CO2 is demonstrated as a single step method for making anatase-TiO2/carbon nanoparticles throughout the pressure and temperature ranges 5–40 MPa and 30–50 °C, respectively.
关键词： core-shell particles,pulsed laser ablation,nanoparticle size control,supercritical fluids
更新于2025-09-11 14:15:04