Surface NMR Using Laser-Polarized ~(129)Xe under Magic Angle Spinning Conditions

摘要

NMR signals of surface nuclei of solids may be enhanced by the transfer of spin polarization from laser-polarized noble gases. Until now such experiments have not been feasible under conditions of magic angle spinning. In the present contribution it is shown that laser-polarized ~(129)Xe can be inserted into a spinning rotor under continuous-flow conditions using helium as a carrier gas. Effective adsorption of xenon on the sample occurs at temperatures of about 163-173 K making possible the observation of a spin polarization induced nuclear Overhauser effect (SPINOE) from the laser-polarized ~(129)Xe to surface ~1H nuclei to SiO_2 (AEROSIL300). This technique opens the way to selectively enhanced high-resolution multinuclear surface NMR experiments.