Characterization of colloidal silver nanostructures produced by pulsed laser ablation in different liquids

Fabrication of silver nanoparticle colloids using nanosecond pulsed laser ablation in liquid is studied. Laser ablations of silver target in chloroform, toluene and ethanol were performed to prepare different nanosize metal colloids. Both fundamental wavelength (1064 nm) and second harmonic (532 nm) of Nd: YAG laser system were used. The influence of the laser wavelength on the morphology, size distribution, shape and optical properties of the produced nanoparticles was studied by transmission electron microscopy (TEM) and UV-Visible absorption measurements. The selected area electron diffraction (SAED) was employed to identify the phase composition of the formed nanostructures. Nanoparticles in chloroform show a large difference in the mean size at both laser wavelengths used — 3,2 nm at 1064 nm and 43 nm at 532 nm. The laser ablation in toluene at both laser wavelength used results in formation of nanoparticles with relatively small mean size (up to 5 nm). Silver nanoparticles in ethanol produced by 1064 nm show mean size of 20 nm while those prepared by second harmonic — 45 nm. The nanoparticles produced by ablation in chloroform and toluene do not show surface plasmon resonance (SPR) absorption in their optical absorption spectra. In contrast the colloidal nanoparticles produced by laser ablation in ethanol exhibit plasmon behavior. The presented method is an alternative to the widely used chemical methods for the preparation of colloidal solutions with certain characteristics enabling their application in the printed electronics to obtain the conductive tracks, and also for the preparation of nanostructured surfaces for surface-enhanced Raman spectroscopy (SERS).