NMR spectroscopic investigations of surface and interlayer species on minerals, clays and other oxides

摘要

The behavior of chemical species adsorbed on solid surfaces and exchanged into clay interlayers plays a significant role in controlling many natural and technologically important processes, including rheological behavior, catalysis, plant growth, transport in natural pore fluids and those near anthropogenic hazardous waste sites, and water-mineral interaction. Adsorption and exchange reactions have been the focus of intense study for many decades (see, e.g., references 1-6 for itnroductions). Only more recently, however, have there been extensive spectroscopic studies of surface species (e.g., references 7-11). Among the spectroscopic methods useful for studying surface and exchanged species (e.g., infrared, X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectrosocpy (XAS)), nuclear magnetic resonance spectroscopy (NMR) has the considerable advantage of providing not only structural information via the chemical shift and quadrupole coulping constant but dynamical informaiton in the Hz-mHz range via lineshape analysis and relaxation rate measurements.~7,12-14