Demonstrating the Spatial Resolution of Field Gradient NMR

In recent years, field gradient NMR has become a method of increasing importance in measuring very small dislocations of molecules. Rough estimations indicate that, by utilizing large field gradients, one should be able to detect motions down to the 10-nm scale. However, this limit has not yet been experimentally detected. In this paper, we present a method that allows the direct measurement of the spatial resolution of field gradient NMR. For our experimental setup, utilizing an extremely large static field gradient of about 180 T m-1, we find a lower limit of 7 nm, thus for the first time confirming the expected resolution. Furthermore, we discuss the effect of unwanted vibrations as a limiting factor of the method. Copyright 1998 Academic Press.

2D Deuteron Exchange NMR and Stimulated Echoes: Molecular Dynamics of the Vacancy Diffusion in Polycrystalline Benzene

Since in crystalline benzene the unit cell consists of four differently oriented molecules, the vacancy diffusion is expected to go along with a corresponding molecular reorientation. Therefore, 2H NMR is able to yield detailed information about the time scale and local geometry of this jump diffusion process. We have carried out 2H NMR stimulated echo and 2D experiments. These data, their fit to calculated spectra, and a comparison between the (1D) stimulated echo treatment and the 2D analysis are presented. Copyright 1998 Academic Press. Copyright 1998 Academic Press