Direct Approach to Pulse Dipolar Spectroscopy Measurement of Mean Distance between Spins by Electron Paramagnetic Resonance

An analytical approach is demonstrated for the direct calculation of the mean distance between a pair of spins from pulse dipolar spectroscopy measurements by electron paramagnetic resonance. This direct approach uses the Mellin integral transform and does not measure the spectrum of distances between spins, offering substantial increases in sensitivity. The approach provides accurate a priori prediction of the uncertainty for a mean distance measurement, based only on experimental measurement parameters and the final signal-to-noise ratio. The feasibility of this approach is confirmed by comparison with the standard indirect approaches using a set of in silico measurements. The new approach demonstrates comparable accuracy and possibilities for enhancing sensitivity.