The synthesis of metallic nanoparticles by femto-second laser ablation

Abstract

Nanoparticles are generally used to indicate particles with dimensions less than 100 nanometers. With such fine dimensions, a great proportion of atoms or molecules are exposed on the total surface. Metal existing as nano-scale particles have special properties never discover before when they were bulk material of micro-scale and above. A list of nanoparticles application was discussed in the report, including its industrial potential and commercial value. Literature review was done on established processes of nanoparticle synthesis. The review had taken in account the principle of each process, their advantages and limitations, their yield quantities and qualities. Most of these processes are limited by the specific chemical reaction equations and equipments, know as recipes. Usually, these different recipes are not inter-changeable for different materials. To overcome this short fall, in recent, there has been great interest to explore the use of physical and mechanical methods. Laser process does not share these same problems. The very same set of equipment could be used to synthesize many materials without the concern of the recipes. The final nanoparticles material and start material could be the same. The use of femto second laser ablation had gained much interest in current research around the globe. With its short pulse width, femto second laser is able to deliver the necessary energy to process the precursor material, yet fast enough not to affect its properties. However, the actual mechanism and sub-processes of femto second laser ablation to syntheses nanoparticle has not been fully explained before. A model was proposed by the writer, in the attempt to describe the process of metallic nanoparticles synthesize in aerosol form. A series of experiments runs were conducted to verify the model. The accuracy and robustness of the model were discussed together with its limitation. The report ended with suggestions for future works to improve further on the model limitation.