Unveiling Solvent Effects on Femtosecond Laser-Irradiated Au/Fe3O4 Colloidal Nanoparticles: The Acetone Effect
The interplay between laser parameters and liquid environments dictates the outcome of femtosecond laser-induced nanoparticle modification. We present a study of gold and iron oxide nanoparticles in water and a water-acetone mixture, irradiated with femtosecond lasers at 808 nm and 404 nm. While aggregation was observed in pure water at both wavelengths, the results revealed a strong stability and a rather unexpected wavelength-dependency in the acetone-water mixture. In this case, 808 nm irradiation produced some decrease in nanoparticle sizes, while 404 nm led to some nanoparticle growth. As a result, the acetone effect is found to be twofold: (i) on one hand, it helps to prevent aggregation; (ii) on the other hand, it acts as a reactive medium allowing to tune the nanoparticle size and composition simply by changing laser wavelength. So, this work emphasizes that solvent physical properties as well as laser-induced chemical processes in the solvent are not merely secondary effects but can dominate the final morphological outcome, providing a predictive framework for nanoparticle synthesis.