Abstract
Silver nanoparticles dispersed Polyvinylpyrrolidone (PVP) nanocomposites were prepared by in-situ chemical reduction of silver nitrate (AgNO3) from an ethanolic solution of PVP. The prepared nanocomposite films were subjected to ultraviolet (UV) irradiation at room temperature for different times. The effect of UV-irradiation has been studied through electron microscopy, optical spectroscopy and FTIR spectroscopy. The appearance of Surface Plasmon Resonance (SPR) band at ~ 420 nm in the UV-Visible absorption spectra indicates the presence of the silver nanoparticles. The optical band gap values were found to reduce from 4.90 eV in pure PVP to 4.11 eV for PVP-Ag nanocomposite prior to irradiation. This value is further reduced to 3.55 eV after UV irradiation for 180 minutes. Such a reduction in optical band gap may be linked to the increased conjugation in PVP matrix as an effect of embedding of silver nanoparticles followed by UV-irradiation, as observed through FTIR analysis.
Keywords
Ag nanoparticles, UV irradiation, Optical band gap, Urbach’s energy, Nanocomposite, PVP-Ag, FTIR.
Citation
R. PAL CHAHAL, S. MAHENDIA, A. K. TOMAR, Effect of ultraviolet irradiation on the optical and structural characteristics of in-situ prepared PVP-Ag nanocomposites, Optoelectronics and Advanced Materials - Rapid Communications, 4, 10, October 2010, pp.1546-1550 (2010).
Submitted at: July 8, 2010
Accepted at: Oct. 14, 2010