Paper PS-ThP3
Diagnosis of Gold Nanoparticle Synthesis in Solution Plasma by Coherent Anti-Stokes Raman Spectroscopy

Thursday, October 21, 2010, 6:00 pm, Room Southwest Exhibit Hall

The performance of the electrical discharges in the aqueous solution presents modern and ecologically very attractive way of the synthesis of nanoparticles. Such kind of techniques are known for the production of very active species like hydrogen radicals, hydroxyl radicals, ozone, aqueous electrons, UV light, etc., which are characterized by its very high reactivity. Although both oxidation and reduction agents were generated in the plasma, gold, platinum, and copper ions were reduced by the plasma. In order to control the reactions in solution plasma, the understandings of activated species and their behaviour are needed.

In this paper we present process diagnosis of gold nanoparticles synthesis in solution plasma based on coherent anti-stokes Raman spectroscopy (CARS). This discharge is generated between two wire type electrodes faced one to each other and driven by bipolar dc pulse power supply. Utilization of this power supply gave us a possibility of an intensive and stable working condition even at lower liquid conductivities. Operation conditions of this power supply lie in the frequency range 0-50 kHz, with minimum pulse length, 2 ms, and maximum voltage, 1.5 kV. In order to obtain desired conductivity of liquid, a small amount of KCl was added into the water. Initial [AuCl₄]⁻ concentration and pH were varied. The reactor was placed on the stage of the optical microscope with CARS system. The morphology of the nanoparticles obtained was observed by transmission electron microscopy (TEM). The solution after discharge was also analyzed by UV-Vis spectroscopy and ICP-MS.