EXPLORING THE INTERNAL STRUCTURE OF MESOPOROUS POWDERS AND THIN FILMS BY CONTINUOUS FLOW LASER-ENHANCED ~(129)XE NMR

摘要

Continuously circulating flow of laser hyperpolarized (HP) ~(129)Xe NMR technique has been used to study the porous structure of ordered purely siliceous MCM-41, SBA-15 mesoporous materials and mesoporous SiO_2 and TiO_2 thin films. The use of hyperpolarized xenon allows us to measure spectra at very low concentration of xenon where xenon reflects mainly interaction between the adsorbed xenon atoms and the surface. Variable temperature measurements allowed us to obtain information on the heat of adsorption of xenon on the surface and to evaluate the chemical shift of xenon in interaction with the surface.