Structural features and existence of three photon absorption in Ag doped TiO2 nanoparticles, synthesized by sol-gel technique

Ag doped TiO2 nanoparticles with various amount of Ag were synthesized through sol-gel technique. The optical, structural and framework substitution of the resultant particles was analyzed by UV-vis diffuse reflectance (UV-DRS) spectroscopy, X-ray diffraction (XRD), Raman, Transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) techniques. Results indicated that incorporation of Ag promoted the growth of TiO2 grains, agglomerated them and shifted the absorption edge to a lower energy. The incorporation of Ag in TiO2 was also confirmed by fluorescence quenching. The non linear optical response and optical limiting effects of the prepared samples was studied by a z-scan technique in which the Ag doped TiO2 nanoparticles dispersed in ethylene glycol were excited at 532 nm using 7 ns Nd:YAG laser pulses. The data fits well to a three-photon type nonlinear absorption process and is attributed to excited state absorption occurring in the nanostructures. It was seen that the optical nonlinearity was more prominent as the volume fraction of Ag concentration increased. (C) 2012 Elsevier B. V. All rights reserved.