SYNTHESIS AND MODIFICATION OF COLLOIDS WITH SILVER NANOPARTICLES BY LASER ABLATION IN DEIONIZED WATER

Abstract

Colloids with silver spherical nanoparticles were obtained by pulsed laser ablation technique in liquids. The laser parameters for the synthesis were: 1064 nm wavelength, 10 ns laser pulse duration, 15.7 mJ energy per pulse, and 2400, 3600 as well as 4800 number of laser pulses. The infrared laser radiation was focused on the surface of a silver target submerged in deionized water. Each synthesized colloid (reference sample) was post-irradiated with the same laser considered for the synthesis, but with an incident energy of 8.3 mJ. The post-irradiation were performed with a repetition rate of 10 Hz and several numbers of pulses. During the post-irradiation, the optical breakdown of the colloid occurred at the half height of it. The characterization of the colloids was carried out with ultraviolet-visible spectroscopy and scanning electron microscopy techniques. The analysis of the maximum absorption, integral of the absorption spectrum in the near infrared interval (from 600 nm to 800 nm), and the post-irradiation number of pulses suggest that as the number of pulses increases, ablation as well as fragmentation of nanoparticles up to a critical size, aggregation, agglomeration, and sedimentation of nanoparticles occur in the colloid. A dependence was found between the optical properties of silver nanoparticles with synthesis conditions and the colloids post-irradiated with a pulsed and focused laser.