Abstract—In this paper we report the measurement of nonlinear refractive index of colloidal Ag nanoparticles and fabrication of Ag nanoparticles. In order to fabricate the colloidal silver nanoparticles laser ablation method has been used. A silver coin as a target (purity 99.9 %) was ablated by a Q-Switched Nd: YAG laser with a fluence of about 91 mJ/cm2 at a repetition rate of 10 Hz at room temperature. In order to characterize these particles transmission electron microscopy (TEM) and spectrophotometry (from UV to NIR) have been used. The average size of fabricated nanoparticles is ~ 20 nm. The importance of morphology of nanoparticles has been investigated. We used the Z-scan technique to investigate the nonlinear refractive index of Ag nanoparticles. The excitation source was a CW 532nm Second harmonic Nd:YAG laser with a beam power of 55 mW. Mostly used applications of silver nanoparticles have been studied; silver nanoparticles are considered as biocompatible and low in toxicity and have good potential for biological applications. Lately silver nanoparticles have found a novel approach in different fields of medicine, biology and industry. In this paper n2 refers to nonlinear refractive index ,Δ Tp-v is the difference between the normalized peak and the valley transmittance. s is the aperture linear transmittance. L_eff is the effective thickness of the sample. EIS, SPR, TEM and SEM refer to: electrical impedance spectroscopy, surface plasmon resonance, transmission electron microscope and scanning electron microscope,respectively.

Index Terms—Ag nanoparticles, laser ablation, nonlinear refractive index, z-scan.

A. Granmayeh Rad is with the Roudehen Branch, Islamic Azad University, Tehran, Iran (e-m ail: granmayeh@riau.ac.ir).
H. Abbasi is with the Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran (e-mail: hamed.abbasi@srbiau.ac.ir).
K. Golyari is with the Department of Physics, Tehran University, Tehran, Iran(e-mail:keyhan.golyri@gmail.com).

Cite: Adeleh Granmayeh Rad, Hamed Abbasi, and Keyhan Golyari, "Fabrication and Nonlinear Refractive Index Measurement of Colloidal Silver Nanoparticles," International Journal of Applied Physics and Mathematics  vol. 2, no. 2, pp. 135-139, 2012.