Fabrication and Size-Dependent Optical Properties of FeO Nanoparticles Induced by Laser Ablation in a Liquid Medium

We report the fabrication of FeO nanoparticles by pulse laser ablation of pure iron plate in the poly(vinylpyrrolidone) solutions. It has been found that the particle size can be controlled in a wide range from 45 to 5 nm by the surfactant concentration from 0.01 to 0.2 M. The optical absorption measurements of the obtained colloidal solutions show that the optical absorption edge red shifts with reduction of the particle size and exhibits the optical features of the semiconductor with indirect band gap. The red shift is attributed to lattice defects in the nanoparticles. This study shows that pulse laser ablation in liquid media is a good method to synthesize some nanoparticles with special structures, which are difficult to produce by other conventional methods.