Spin Exchange Between Charged Paramagnetic Particles in Dilute Solutions

Salikhov, K. M.; Mambetov, Aydar Ye.; Bakirov, M. M.; Khairuzhdinov, I. T.; Galeev, R. T.; Zaripov, R. B.; Bales, Barney L.

doi:10.1007/s00723-014-0571-1

Cited by 16 publications

(5 citation statements)

References 15 publications

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“…In order to resolve the anomalous behavior that arises when the standard relations are used to calculate the concentration coefficients, we went beyond these relations by applying the formalism of the kinetic equations for the spin density matrix. 1,12,21 This formalism, which was previously used to calculate the HSE effects on the EPR parameters within the CDM, is extended here by including the secular part of DD interactions between radicals. We considered the kinetic equations for the spin density matrices of a system with A and B radicals with different Zeeman frequencies in an external magnetic field.…”

Section: ■ Resultsmentioning

confidence: 99%

“…We considered the kinetic equations for the spin density matrices of a system with A and B radicals with different Zeeman frequencies in an external magnetic field. ,, Relative motion of radicals in the system is described by the CDM where the radicals interact by the HSE interaction and the secular part of DD interaction. We calculated the spin dephasing rate, the coherence transfer rate, and the frequency shift of A radicals produced by interactions with B radicals (see Appendix S2).…”

Section: Resultsmentioning

confidence: 99%

“…We considered the kinetic equations for the spin density matrices of a system with A and B radicals with different Zeeman frequencies in external magnetic field [1,12,21].…”

Section: Relations From the Kinetic Equations For The Spin Density Ma...mentioning

confidence: 99%

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Continuous Diffusion Model for Concentration Dependence of Nitroxide EPR Parameters in Normal and Supercooled Water

Merunka

Perić

2017

J. Phys. Chem. B

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Electron paramagnetic resonance (EPR) spectra of radicals in solution depend on their relative motion, which modulates the Heisenberg spin exchange and dipole-dipole interactions between them. To gain information on radical diffusion from EPR spectra demands both reliable spectral fitting for finding the concentration coefficients of EPR parameters and valid expressions between the concentration and diffusion coefficients. Here, we measured EPR spectra of the 14N- and 15N-labeled perdeuterated TEMPONE radicals in normal and supercooled water at various concentrations. By fitting the EPR spectra to the functions based on the modified Bloch equations, we obtained the concentration coefficients for the spin dephasing, coherence transfer, and hyperfine splitting parameters. Assuming the continuous diffusion model for radical motion, the diffusion coefficients of radicals were calculated from the concentration coefficients using the standard relations and the relations derived from the kinetic equations for the spin evolution of a radical pair. The latter relations give better agreement between the diffusion coefficients calculated from different concentration coefficients. The diffusion coefficients are similar for both radicals, which supports the presented method. They decrease with lowering temperature slower than is predicted by the Stokes-Einstein relation and slower than the rotational diffusion coefficients, which is similar to the diffusion of water molecules in supercooled water.

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Section: ■ Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Continuous Diffusion Model for Concentration Dependence of Nitroxide EPR Parameters in Normal and Supercooled Water

Merunka

Perić

2017

J. Phys. Chem. B

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“…In theoretical treatment, we modeled dissolved radicals as continuously diffusing hard spheres and applied formalism of the kinetic equations for the spin density matrices of radicals. 4,7,18,19,21 From this comparison, we obtained the diffusivities of 15 N-and 14…”

Section: T H Imentioning

confidence: 99%

“…The linear concentration coefficient of Λ, determined as the slope of the linear function, was compared to its theoretical dependence on radical diffusivity (Figure S5). In theoretical treatment, we modeled dissolved radicals as continuously diffusing hard spheres and applied formalism of the kinetic equations for the spin density matrices of radicals. ,,,, From this comparison, we obtained the diffusivities of 15 N- and 14 N-pDTEMPONE at each temperature, which show similar values (Figure ). The diffusivity of pDTEMPONE, calculated as the average value of the diffusivities of 15 N- and 14 N-pDTEMPONE, is presented as a function of temperature in all liquids (Figure ).…”

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confidence: 99%

Radical Diffusion Crossover Phenomenon in Glass-Forming Liquids

Slade

Merunka

Perić

2022

J. Phys. Chem. Lett.

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We studied the diffusivities of a nitroxide radical at various temperatures in six glass-forming molecular liquids by electron spin resonance. By comparing the radical diffusivities and solvent self-diffusivities, we found that the radical diffusivities are lower than the self-diffusivities at high temperatures and approach them at low temperatures in all liquids. This crossover behavior was considered as evidence that a single-molecule diffusion process transforms into a collective process with temperature lowering. The crossover phenomenon was analyzed by a novel, simple diffusion model, combining collective and single-molecule diffusion processes, and it was compared to the Arrhenius crossover phenomenon. The obtained results suggest that future studies of tracer diffusion could contribute to a better understanding of diffusion mechanisms in glass-forming liquids. The proposed diffusion model could be used to study the crossover phenomena of tracer diffusion measured by other techniques, and it could serve as a base for developing more advanced models.

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Theory of Spin Exchange in Dilute Solutions

Salikhov

2019

Fundamentals of Spin Exchange

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Spin Exchange Between Charged Paramagnetic Particles in Dilute Solutions

Cited by 16 publications

References 15 publications

Continuous Diffusion Model for Concentration Dependence of Nitroxide EPR Parameters in Normal and Supercooled Water

Continuous Diffusion Model for Concentration Dependence of Nitroxide EPR Parameters in Normal and Supercooled Water

Radical Diffusion Crossover Phenomenon in Glass-Forming Liquids

Theory of Spin Exchange in Dilute Solutions

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