A Study On Preparation Of Metal Nanoparticles Colloid By Pulsed Laser Ablation In Liquid

As new zero-dimensional nanomaterials, the unique chemical andphysical of metal nanoparticle colloids are different from those of bulk. Sothese nanoparticle colloids have shown very promising applications suchas catalysts, absorber, biosensor and electronic nanodevices. However, allof the present methods for preparation of nanomaterials have their owndrawbacks such as low purity, large sizes and broad size distributions.Therefore, the investigation of method for preparation of nanomaterials toavoid the drawbacks as described above is of extreme practical andtheoretical importance.In this thesis, a comprehensive review of the research history andcurrent status of nanomaterials preparation were first presented. Then themetal nanoparticles colloid was prepared by pulsed laser ablation in theexperimental apparatus which was designed and made by oursleves.Thirdly, after the component, size distributions and shape were analysedchiefly by means of transmission electron microscopy and UV-visiblespectrophotometer, it was discussed the effects of laser parameters on silver nanoparticle colloids. Forthly, by combination of the experimentalfindings and the model of artificial neural networks, the laser parameterswere optimized and the silver nanoparticles of best characteristic wereproduced. Fifthly, On the basis of optimized laser parameters, it was alsoanalysed the effects of experimental conditions on the metal nanoparticlecolloids. Furthermore, it was also discussed that the effects of laserablation parameters on the silver nanoparticle colloids in terms offragmentation and melting induced aggregation of colloidal particles byself-absorption of laser pulses. The obtained results are as the following:1,The mean sizes and size distributions of nanoparticles aredetermined by laser parameters,ablation time,liquid environment andSDS surfactant.2,Under the same other laser parameter and experimentalconditions, the nanoparticles of best characteristic are prepared by laserablation with different energy density in the same time, in which thefragmentation and melting induced aggregation are balanced.3,Under the same process conditions, the characteristic of Aunanoparticles prepared by laser ablation are the best of all the metals(Ag,Ti and Au).