tailieunhanh - Báo cáo " Silver nanoparticles prepared by laser ablation and their optical characteristics "

Laser-induced thermal explosion of metallic nanoparticles originates from nonlinear optical effect. Nonlinear optical properties of nanoparticle materials depend strongly on their size and shape. Several methods were proposed to produce nanoparticles of a controlled size and welldefined distribution. We studied to prepare silver nanoparticles by laser ablation. The characteristic spectral feature of the silver nanoparticles (peak around 400nm) was found in the absorption spectra measured by a UV-Vis 2450 spectrometer. . | VNU Journal of Science Mathematics - Physics 24 2008 1-5 Silver nanoparticles prepared by laser ablation and their optical characteristics Nguyen The Binh Do Thi Ly Nguyen Thi Hue Le Tu Quyen Department of Physics College of Science VNU 334 Nguyen Trai Thanh Xuan Hanoi Vietnam Received 10 January 2008 received in revised form 19 March 2008 Abstract. Laser-induced thermal explosion of metallic nanoparticles originates from nonlinear optical effect. Nonlinear optical properties of nanoparticle materials depend strongly on their size and shape. Several methods were proposed to produce nanoparticles of a controlled size and well-defined distribution. We studied to prepare silver nanoparticles by laser ablation. The characteristic spectral feature of the silver nanoparticles peak around 400nm was found in the absorption spectra measured by a UV-Vis 2450 spectrometer. The size and shape distribution of silver nanoparticles was observed and analyzed by a transmission electron microscope JEM 1010-JEOL . Two different surfactants were employed namely trisodium citrate dihydrat C6H7Na3O7 and polyvinyl alcohol -CH2-CHOH- n. The size distribution and the UV-Vis absorption spectra of silver nanoparticles depend clearly on the properties and concentration of the surfactant employed. The experimental results were in good agreement with theory and showed advantages of the laser ablation method. Key words Surface plasmon resonance surfactant. 1. Introduction In recent years there has been a great interest in the preparation and application of the silver and gold nanoparticles. Under the short laser pulses irradiation in the spectral range of the surface plasmon resonance metal nanoparticles such as silver or gold nanoparticles are excited to upper electronic states by multiphoton absorption. Through rapid relaxation to their ground state the absorption photon energy can be conversed into thermal energy. Their temperature rises very quickly to reach thresholds for nonlinear effects