Pulsed EPR structural studies in the nanometre range of distances

The possibilities of investigations of the nanostructure of matter by pulsed EPR spectroscopy based on the measurement of the dipole–dipole coupling between the spins of unpaired electrons are considered. Using these methods, one can determine the conformations of long-chain organic biradicals and biomolecules (either doubly spin-labelled or containing paramagnetic metal ions) and study the supramolecular structure of matter, i.e., peptide clustering, heterogeneity of polymer packing, structural details of photosynthetic reaction centres and other complex systems. Investigations of the photoinduced spin-correlated radical pairs also reveal the regularities of charge transfer in these systems. The methods are characterised by high accuracy of measurements (0.03 nm) and can be used for measuring distances in the 1.5–10 nm range.