Research On Scattering Properties Of Au And ZnO Nanoparticles Dispersed In Water

Nano materials have a wide application prospect in biological medicine and chemical engineering,because of their specific volume effect,dimensional effect,surface effect,tunnel effect,and their properties of physical absorption,chemical reaction,and photocatalytic.The recent development of nanotechnology has brought a new opportunity for conducting thorough studies on the scattering properties of semiconductor and metal nanoparticle systems.Among them,Au and ZnO nanoparticles of various shapes and sizes dispersed in water are employed for fundamental research because of their high stability,good optical quality,and ease of preparation.This work is mainly about the scattering properties,especially the backward stimulated scattering and stimulated Brillouin scattering properties of Au and Zn O nano particles dispersed in water with different size,shape,and concentration.In order to study the scattering properties of the samples,we designed different experiments and theoretical methods about the transmission,absorption,scattering intensity angular distribution and stimulated scattering property.To study the properties of transmission and absorption of different samples,the transmission and absorption spectrum were measured by spectrophotometer,the scattering extinction coefficient and scattering cross section of ZnO nano sphere sample were calculated as well based on the transmission spectrum.From the experimental results we found two absorption band at 530 nm and 950 nm in Au nano rod sample,a absorption band at 530 nm in Au nano sphere sample,and a sharp attenuation at 370 nm in ZnO nano sphere sample,respectively.Meanwhile,we measured the scattering intensity angular distribution of different samples and studied the relation between scattering intensity angular distribution and size and wavelength.To analyze the physical mechanism,we also build a modle by Mie theory.Further more,the backward stimulated scattering effects pumped by 532 nm laser were observed in 13x90 nm Au nanorod,10 nm Au nano sphere and 50 nm ZnO nano sphere samples,respectively.Then this work introduced the stimulated Brillouin scattering in Au nano particle sample and the stimulated Mie scattering in ZnO nano particles sample.The threshold,power,frequency-shift and linewidth were also cauculated and analyzed.This work also studied the relation between different parameters of backward stimulated scattering and concentration,size and other parameters of samples,and compared the stimulated scattering properties in different samples.Besides,based on the acoustic wave equation in fluid,the relations between acoustic velocity,refraction index and concentration in fluid have been calculated,and then we got the relation between SBS frequency-shift and concentration,which also confirmed the experimental results.