Current state of the spin exchange theory in dilute solutions of paramagnetic particles
K.M. Salikhov E.K. Zavoiskii Kazan Physicotechnical Institute, Kazan Scientific Centre of the Russian Academy of Sciences, Sibirskii trakt 10/7, Kazan, 420029, Russian Federation
The kinetic equations for single-particle spin density matrices with Heisenberg exchange interaction in bimolecular collisions of particles and dipole-dipole spin-spin interaction between particles are presented. The results of calculations of the effective spin exchange radius for a number of model situations are summarized. The characteristic manifestations of spin exchange and dipole-dipole spin-spin interaction in the form of electron paramagnetic resonance (EPR) spectra are described. A modern approach to determining the rate of the bimolecular spin exchange process from the analysis of EPR spectra is presented. Set forth a new interpretation of the effect of exchange narrowing of ESR spectra.
Keywords: spin probes, the exchange and the dipole-dipole interaction, the rate constant for spin exchange, decoherence of spins, transferring spin coherence, the shape of the EPR spectra, mixed form of spectral lines (absorption+dispersion), the exchange narrowing of the spectra DOI:10.3367/UFNe.2018.08.038421 Citation: Salikhov K M "Current state of the spin exchange theory in dilute solutions of paramagnetic particles" Phys. Usp., accepted
Received: 28th, June 2018, revised: 17th, August 2018, accepted: 31st, August 2018