Limits of deconvolution in enhancing the resolution in EPR imaging experiments

The limits in resolution enhancement, obtained by deconvoluting experimental spectra with the zero gradient line in the frame of electron paramagnetic resonance imaging (EPRI), are discussed. The enhancement is evaluated for different values of the signal-to-noise ratio and different line widths of the spectra. Deconvolution requires the use of a low-pass filter in the Fourier domain. The cut-off frequency of this filter can be taken at the intersection between the signal and noise power spectra. This choice gives an automatic criterion to select the filter bandwidth it deconvolution is performed on a large data sequence. The effect of deconvolution is described by a parameter r that gives an indication of the gain achieved in performing deconvolution. It is defined as the ratio between the widths of the natural line shape and the filter response. Its value depends on the signal-to-noise ratio and on the line width of the original spectrum.