Non-linear optic properties of colloids prepared by metal targets’ laser ablation in dimethylsulfoxide

Abstract

A set of colloids on the base of aluminum, nickel, and zinc was prepared by their targets’ ablation in dimethylsulfoxide medium. The samples were characterized with UV-vis spectroscopy, transmission electron microscopy, and dynamic light scattering methods. The substantial non-linear attenuation was observed with z-scan techniques using pulsed neodymium laser (532 nm, 14 ns). The transmittance of the samples diminish- es when the light intensity increases. The photoacoustic signal amplitude rises with the energy density in- creasing according to the sublinear law. The dependencies of the attenuation linear coefficient and pressure generation efficiency on the pulse energy density were described with power laws with a threshold of the ef- fect and the parameters were estimated. We found out that the dependencies’ parameters change when the colloids were diluted. The pear pressure was determined using ferrocene as a calibration standard. It is shown that the values of peak pressure could not be explained in terms of thermal expansion of the substance. The results are discussed in terms of the non-linear attenuation mechanism concerned on the substance evapora- tion leading to vapor bubbles formation around the nanoparticles.