| Abstract [eng] |
In recent years, there has been a tremendous amount of interest and attention in metal nanoparticles. This is due to the unique optical, electrical, chemical and mechanical properties of the nanoparticles. The ability to understand and manage these properties allows the use of metal nanoparticles in the practical development of more advanced new technologies. Nanoparticles are already widely used in medicine, sensors, catalysis and elsewhere. In order to be suitable for the application of metal nanoparticles in many different fields, they must have a certain chemical stability, be monodisperse, have a certain shape, but at the same time to be clean and do not interfere with adjacent biochemical reactions. Laser ablation in liquid method is currently considered to be one of the most efficient and best – performing methods for the formation of nanoparticles. The nanoparticles produced by this method are extremely small, pure, and the morphology of the particles can be controlled by changing the type of medium in which the process takes place. In this work gold and silver metal nanoparticles were produced using 1030 nm wavelength femtosecond laser. Optimal laser parameters for the formation of metal nanoparticles were determined: 1,30 W laser power, 200 kHz repetition rate, 10 000 imp/mm pulse density and 20 mm/s laser beam scanning speed. The formation of metal nanoparticles was proved by coloring of the deionized water by red and yellow color for gold and silver respectively. By measuring the absorption spectra of colloidal solutions of gold and silver nanoparticles, it was found that they correspond to the localized surface plasmons resonance of these metal nanostructures. The plasmon resonance peaks for gold nanoparticle colloids were in a range from 513 nm to 547 nm, and for silver colloids it vary from 398 nm to 425 nm. The size and shape of the metal nanoparticles were evaluated with a scanning electron microscope. Nanoparticles fabricated in deionized water were found to have spherical shape, and the size of nanoparticles were 36 ± 21 nm and 25 ± 16 nm for gold and silver respectively. Metal nanoparticles formed in solutions of different concentrations of Tween 80 surfactant are in spherical shape, which size ranges between 20 – 40 nm for gold and 50 – 70 nm for silver. Gold nanoparticles synthesized in sodium citrate solutions are spherical with the size between 15 – 35 nm range. Gold and silver nanoparticles synthesized in halogen salt solutions appears in more complex morphology like triangular, pentagonal, cubic and other nanostructures, which size is in a range from 24 nm to 54 nm. It was observed that silver nanoparticles in halogen salt solutions are not stable and morphology changes over time as the color of these solutions has changed as well as size of the structures. Thus, it can be summarized that the selection of ablation media and ultrashort pulsed laser parameters determines the size and morphology of the synthesized metal nanoparticles. |
