ABSTRACT
The image obtained from a two-dimensional (2-D) spectral-spatial experiment displays the electron paramagnetic resonance (EPR) spectrum as a function of one spatial coordinate. In the spectral-spatial imaging experiment, the magnetic-field gradient is changed as a function of a, which changes the scaling between the spectral and spatial dimensions. Spectral-spatial EPR imaging has been extended to two spatial dimensions by rotating the sample and obtaining a 2-D spectral-spatial image at each orientation. Since spectral-spatial imaging requires the use of a series of gradients and magnetic-field scan widths, an obvious question is what happens if the spectra at the highest gradients and scan widths include lines that are not present in the spectra at low gradient. Spectral-spatial imaging has been applied to the transport of nitroxyl radicals in nonuniform media, irradiated sulfuric acid glasses, and nitroxyl probes of oxygen concentration. The ability to image portions of spectra substantially increases the range of systems to which EPR imaging can be applied.
