Synthesis, Characterization And Nonlinear Optical Properties Of Laser-induced Au Colloidal Nanoparticles
R. Kuladeep, K. Shadak Alee, L. Jyothi and D. Narayana Rao
Volume 4, Issue 6, Page 482-487, Year 2013, Ion Beam Special Issue | DOI: 10.5185/amlett.2012.ib.117
Keywords: Gold colloidal nanoparticles; UV-visible absorption spectrum; surface plasmon; TEM, saturable absorption; reversesaturable absorption.
Gold (Au) colloidal nanoparticles (NPs) have been synthesized by direct irradiation of gold precursor (HAuCl4) solution in polyvinyl alcohol (PVA) matrix using nanosecond laser pulses at different irradiation fluencies and exposure times. Appearance of wine and dark wine colors indicated the formation of Au NPs. Transmission electron microscope (TEM) images exhibited spherical shaped particles and X-ray Diffraction (XRD) pattern confirms polycrystalline nature of Au NPs with cubic structure. Au NPs displayed negative nonlinearity and exhibited a shift from saturable absorption (SA) at lower intensities to reverse saturable absorption (RSA) accompanied by nonlinear scattering at higher excitation intensities in nanosecond regime at 532 nm. Two-photon absorption (TPA) is attributed to be responsible for the RSA behavior. Copyright © 2013 VBRI press.