Synthesis of stable silver colloids by laser ablation in water

The stable colloid with silver nanoparticles has been produced by irradiation of metal target in deionized water by pulse 1064 nm laser. The dependences of the nanoparticle size and colloid stability on fluence, ablation time, surface conditions of the target, and thickness of the water layer have been studied. The sizes and shape of nanoparticles have been measured by dynamic light scattering and by scanning electron microscopy. It has been shown that decrease of the water layer thickness above the target surface leads to increase of the colloid stability. The proper number of treatment cycles allowed to prepare the target surface for production of the nanoparticles with average size about 34 nm obtained by statistical analysis of the scanning electron microscope images. Several methods have been used to increase the colloid stability: (1) increase of the laser fluence, (2) decrease of the water layer thickness above the target surface, (3) the treatment of the target surface by laser beam scanning. The subsequent increase of the colloid concentration by partial drying slightly enhanced the nanoparticle size. The optimized synthesis conditions and drying parameters allowed to produce the pure colloid with concentration about 0.5 g/l and stability over a month of almost spherical silver nanoparticles with typical size 45±5 nm.