Fabrication of silver nanoparticles by laser ablation technique: their characterization and uses

Abstract

Nano structure materials have generated much interest in recent years. Nanotechnology involves the fabrication of particles at the nano scale level and subsequent use of those nano structure materials for better, more efficient and cost effective technology. Metal nanoparticles are more attractive because of their size dependent physical and chemical properties. Silver nanoparticles have advantage over all other metal nanoparticles because of their optical, electrical and thermal properties. A unique property of spherical silver nanoparticles is that the extinction peak of silver nanoparticles in water can be tuned over a range of 380 – 500 nm by changing the particle size. This chapter deals with colloidal solution of silver (Ag) nanoparticles in deionized nanopure water fabricated by Laser ablation technique without the use of any chemicals. The brilliant color of the colloidal solution of silver nanoparticles is different from the bulk silver. The spectral characterization and some morphological studies of these nanoparticles were done using UV-Vis spectroscopy and SEM/EDX experiments, respectively. The ablating laser pulse energy and the ablation time were the key parameters to control the size of the fabricated nanoparticles. It was observed that the size of nanoparticles decreases with increasing laser power and hence the UV-Vis spectra of the nanoparticles show a monotonic blue shift with ablating pulse power. The blue shift in the absorption spectra and a narrowing of the absorption line were also observed with increasing re-ablation time of already ablated silver colloids. Possible explanations of all these observations of fabricated silver nanoparticles are discussed in this chapter. The results of the study of the possible coagulation of the silver nanoparticle with passage of time after fabrication are also presented in this chapter. Besides its applications as conductive inks and pastes for their high conductivity, both electrical and thermal, silver nanoparticles for their unique optical properties, can be used in molecular diagnosis, textiles, photonic cells and in enhanced optical spectroscopic techniques such as metal-enhanced fluorescence (MEF) and surfaceenhanced Raman scattering (SERS). The use of silver nanoparticles in antimicrobial coatings, wound dressings and in biomedical devices/sensors have also generated great interest.