Rayleigh scattering from gaseous phase nanoparticles synthesized by pulsed laser ablation of ZnO

Abstract

Rayleigh scattering and photoluminescence techniques are used to show the evidence of formation of ZnO nanoparticles in gaseous phase due to condensation of laser ablated ZnO plasma species in air. The intensity of Rayleigh scattered signal increases with the increase in time delays between the probe and the ablating pulse. Plasma emission dominates close to the target surface whereas Rayleigh scattered signal dominates at larger distances where nanoparticles are abundant. Photoluminescence spectra are observed in laser ablated ZnO plasma using fourth harmonic of a Nd:YAG (yttrium aluminum garnet) laser as an excitation source, which confirms the formation of ZnO nanoparticles in gaseous phase. The photoluminescence profiles observed from gaseous phase ZnO nanoparticles show blueshift with respect to that observed from bulk ZnO under similar excitation condition implying quantum confinement.