Abstract: Silver nanoparticles have been prepared using hydrogen gas as the reducing agent for silver nitrate and poly(vinyl pyrrolidone) as the capping agent; the reaction was carried out at 70 °C for 3 hours. The size of these nanoparticles was found to be about 20 nm as analyzed using transmission electron micrographs. The X-ray diffraction pattern revealed the face-centered cubic (fcc) structure of silver nanoparticles. Optical limiting property of silver nanoparticles is studied. The nonlinear refractive indices of silver nanoparticles were defined by the z-scan technique using CW He-Ne laser (λ = 632.8 nm) at different incident intensities. The magnitude of nonlinear refractive index (n2) was measured to be in the order of (cm2/W) with a negative sign.
