Modeling Solvent Influence on Growth Mechanism of Nanoparticles (Au, Co) Synthesized by Surfactant Free Laser Processes

Co and Au nanoparticles have been synthesized by femtosecond laser ablation and fragmentation in various liquids (n-hexane, diethyl ether, toluene, 2-propanol, acetone, and methanol) to investigate their influences on the size of the generated particles. Results suggest that nanoparticle growth with the absence of surfactants occurs from light absorption by the colloids through diffusion coalescence and can be controlled by the solvent polarity, the processing time, and the laser power. Furthermore, the growth has been related to the electrostatic repulsion energy and to the change in the nanoparticle temperature due to the laser light absorption by using the DLVO theory. Nanosecond laser annealing of Au particles in methanol also confirms the proposed model.