Resolving Structure and Electronics by XANES Spectroscopy in Ordered Porous Oxide Films

LEANDRO ANDRINI; PAULA C. ANGELOMÉ; GALO J. A. A. SOLER-ILLIA; FÉLIX G. REQUEJO

Puerto Iguazú

Simposio; XIX Latin American Symposium on Solid State Physics; 2008

Nanoestructured materials exhibit several difficulties for a detailed and fundamental characterization. Local techniques like Transmission Electron Microscopy, extreme and successfully employed at the Nanoscience field, are specially appropriated by giving a very confined point of view of the characteristics and properties in molecules or materials with a short range order structure. At the same time, these types of techniques are limited in chemically specificity studies or for determining averaged and representative characteristic values. X-ray absorption based techniques allow, even the necessity of synchrotron laboratories or recent less expensive in house alternatives, the chemical sensitivity and average determination in local characterizations for nanomaterials like nanoporous, nanoparticles and nanotubes among others. We study highly ordered mixed oxide porous films and nanoparticles by X-ray Absorption Near Edge Structure (XANES) spectroscopy. We focus on the local structure determination (bond length, coordination, symmetry) and electronics (density of unoccupied states, oxidation state, ligand field effects, energy splitting) of Zr and Ti ions in SiO2 in function of their relative concentration in the thin walls of TiO2-SiO2 and ZrO2-SiO2 in ordered porous films.