Published online by Cambridge University Press: 21 February 2011
The possibilities of acquiring NMR images of solids with conventional imaging apparatuses are explored. To this end a multiple-pulse line-narrowing sequence is introduced which averages both homonuclear dipolar couplings and time independent linear lz, interactions such as chemical shifts and susceplibility shifts. For imaging the multiple-pulse cycle is accompanied by an oscillating magnetic field gradient which phase encodes the spatial location o each spin. The period of the gradient oscillation is matched to the period of effective field toggling such that the multiple-pulse cycle does not average to zero the gradient induced spin evolution. A small radio frequency coil of 3.0 mm i.d. is used since then only modest radio frequency (RF) power is sufficient to generate a strong RF field, and the RF homogeneity is quite good over the sample volume. The resolution of the image is not spatially uniform, but near the center the resolution is better than 100 μm and the resolution at the edges of the image is degraded by only a factor of 3 to 5. Images of solids with acceptable resolution and sensitivity can be collected by this method- with minimal setup time and difficulties.