ABSTRACT
This chapter describes a practical criterion of resolution and outlines some of the experimental limitations on image resolution. Each field of imaging science adopts a criterion for resolution. Improved resolution could be obtained with greater spin densities. The linewidth of the electron paramagnetic resonance (EPR) signal limits the resolution of the image. Any factors that cause frequency variation during the course of data collection are potential causes of uncertainty and loss of resolution in the image unless correction is made for the frequency shifts. For a single-line spectrum, the resolution obtained with multiple-stepped gradients is comparable to that obtained with modulated or static gradients. For one-dimensional images, resolution is determined by the magnitude of the gradient and the linewidth of the EPR signal. The minimum-volume element that can be imaged is limited by signal-to-noise considerations—it must contain enough spins to be detectable by EPR. One approach to EPR imaging is to rotate the sample in the cavity with a goniometer.
