Synthesis of silver nanoparticles in poly(vinyl alcohol) matrix in solution and thin films through laser irradiation.

Here we communicate our experimental results on the synthesis of silver nanoparticles in solution and thin films using silver nitrate and poly vinyl alcohol (PVA) mixture at different concentrations and different laser irradiations. Detailed studies were carried out by varying pulse width, wavelength, exposure time, and energy of the laser. Formation of nanoparticles was confirmed through color change from transparent to yellow. Irradiated solutions and thin films at different concentrations showed plasmon peak in the absorption spectra. Formation of different sized nanoparticles at different energies with peak shift is observed. Transmission electron microscope (TEM) results confirmed the formation of nanoparticles with size of the particles varying from 2 to 200 nm. Formation of silver nanoparticles with hexagonal and different shapes were observed in particular with 355 nm laser irradiation. Influence of wavelength, pulse width, exposure time, and energy in the synthesis of silver nanoparticles is highlighted. Electron diffraction patten of a single nanoparticle in TEM showed polycrystallinity with cubic nature for the silver nanoparticles prepared. We also compared the linear and nonlinear absorption properties of the freshly prepared nanoparticles with nanoparticles solution left in a shelf for a long period of time.

Control of the polarization properties of the supercontinuum generation in a noncentrosymmetric crystal.

A systematic experimental study on the polarization properties of supercontinuum generation (SCG) in a noncentrosymmetric crystal (KDP) is reported. Our studies show that depolarization of the SCG is dependent on the plane of polarization of incident light as well as on the orientation of the crystal, allowing a better control of the polarization properties.