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. (C) 1998 Academic Press.