Basics of UV Laser-Assisted Generation of Nanoparticles

Abstract

An overview is given of the basics of nanoparticle generation by UV laser assisted chemical vapour deposition (LCVD). ArF excimer laser induced tungsten nanoparticle condensation from a WF6/H2/Ar gas mixture is considered as a model system to show the most relevant processes during the nanoparticle formation and the interaction of the nanoparticles with laser light. Parallel phenomena for carbon covered iron nanoparticle formation by ArF excimer laser induced decomposition of ferrocence (Fe(C5H5)2) are also presented. Results on structure and materials composition, reaction pathways for condensation and growth, size distribution, and cooling mechanisms for hot nanoparticles are presented and discussed. In addition, we consider tungsten nanoparticles generated by laser ablation (LA) of a tungsten target and compare the most important aspects of the LCVD and LA methods. Concerning practical applications, optimal conditions for producing particles with a narrow size distribution are sought. It is also shown that optical emission spectroscopy, by analysing the thermal radiation originating from the laser-excited nanoparticles, is capable of monitoring these optimal conditions for the LCVD processes.