Interpretation of the Nature of the Mixed Form of Resonance Lines of the Electron Paramagnetic Resonance Spectrum in a New Paradigm of Spin Exchange: Abnormal “Resonance” of Non-Resonant Spins

• Published in: The journal of physical chemistry. B 2020-07, Vol.124 (30), p.6628-6641
• Main Author: Salikhov, Kev M
• Format: Article
• Language: English
• Subjects: B: Liquids, Chemical and Dynamical Processes in Solution, Spectroscopy in Solution
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/acs.jpcb.0c04424

It is shown that the asymmetric shape of lines in the electron paramagnetic resonance spectra of paramagnetic particle solutions caused by spin exchange in bimolecular particle collisions is due to the fact that, in the experiment, under the conditions of slow spin exchange, an absorption signal of nominally resonant spins and a “resonance” dispersion signal of nominally nonresonant spins with an abnormal phase of their quantum coherence are registered simultaneously. The mixing of these two signals is different for different resonance lines in the observed spectrum. A phenomenological model is proposed that can be used to find the phase of the “resonance” signal of non-resonant spins. The obtained results can be transferred to other systems to study the mechanisms of spectral diffusion, for example, chemical exchange by magnetic resonance methods.