Experimental study of carbon and iron nanoparticle vaporisation under pulse laser heating

The process of vaporisation of carbon and iron nanoparticles induced by a nanosecond Nd:YAG laser pulse at a wavelength of 1,064 nm was investigated. A drop of a volume fraction of both types of particles after the YAG laser pulse was observed by laser light extinction at a wavelength of 633 nm. The nanoparticle sizes and peak particle temperature were measured by the two-colour time-resolved laser-induced incandescence technique. The dependences of the evaporated part of the particle volume fraction and peak particle temperature on laser fluence, particle size and particle formation conditions have been analysed for the carbon and iron nanoparticles. It was found that the process of carbon nanoparticle vaporisation depended on their size and structure, which varied in different formation conditions. It was assumed that the difference in vaporisation process of iron nanoparticles from the bulk was caused by the change of their size and surface tension leading to higher vapour pressure. It is shown that an equilibrium description of nanoparticle vaporisation in laser-induced incandescence model is not valid at high laser fluence and an essential correction of the description of the vaporisation process is necessary.