Xenon Nmr

Abstract

This chapter presents an attempt to cover the entire scientific literature of xenon NMR, encompassing physical, chemical and biological applications involving both spectroscopy and imaging, from the earliest days of NMR to the new opportunities afforded by hyperpolarized Xe. The large, polarizable, electron cloud of the Xe atom endows it with a great sensitivity to its local environment, which is reflected in its chemical shift and electric field gradient. Thus the NMR of Xe(O) largely concerns the physical interaction of the Xe atom with other atoms (including other Xe) through collision and overlap, in the gas and in condensed materials including liquids, polymers, clathrates, porous materials and surfaces. Xe NMR has been used extensively to probe pore spaces and other species present in them, such as metal clusters and paramagnetic centres. Much has also been learned in recent years about the dynamics of Xe in porous media, especially through the use of 2D exchange spectroscopy and diffusion experiments. Particular attention has been focused on efforts to understand the origins and to calculate the chemical shift in microporous materials from first principles, and thus go beyond a qualitative picture. The 10 4 gain in sensitivity of hyperpolarized Xe has been exploited for studies of low-surface-area materials, in low-concentration and time resolution experiments, for polarization transfer to other nuclei, and for imaging. 129 Xe NMR has also played a very major role in the investigation of Xe chemistry (which is now quite extensive), particularly in following chemical reactions and determining structure and bonding characteristics. An extensive updated tabulation of chemical shifts and J-coupling constants is given.