Characterization of Silver Nanocomposite Glasses by X-ray Photoelectron Spectroscopy
J.A. Jiménez, H. Liu, E. Fachini, C.R. Cabrera
University of Puerto Rico, US
Keywords: silver, nanoparticles, europium
Abstract:In this work, X-ray Photoelectron Spectroscopy is employed in the characterization of silver nanocomposite glasses with the object of furthering the understanding of the effect of thermal processing on material optical properties. First, the technique is employed in studying the dependence of Ag binding energies (BEs) on the optical properties of the silver-doped glasses, which in turn depend on heat treatment conditions. The data shows BEs for 3d doublets higher than those reported for bulk silver with a shift towards the bulk value with increasing wavelength of surface plasmon resonance peak position. This behavior is consistent with an increase of the metallic character of silver aggregates as a result of an increase in particle size since in larger metallic clusters, an increased hole screening by conduction electrons decreases the BE. Second, XPS is used to study Eu-doped Ag nanocomposites in order to make clear whether the cause of the PL quenching effect associated with thermal processing is related to a decrease in Eu3+ content owing to reduction to Eu2+ or to the presence of Ag NPs. The data points towards Eu3+-Ag NP interactions as main responsible for the observed quenching effect.