Radical Diffusion Crossover Phenomenon in Glass-Forming Liquids

Slade, Jakov; Merunka, Dalibor; Peric, Miroslav (2022) Radical Diffusion Crossover Phenomenon in Glass-Forming Liquids. The Journal of Physical Chemistry Letters, 13 (15). pp. 3510-3515. ISSN 1948-7185

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Official URL: http://doi.org/10.1021/acs.jpclett.2c00305

Abstract

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.

Item Type:

Article

Uncontrolled Keywords:

Diffusion; Liquids; Molecules; Solvents; Transport properties

Subjects:

NATURAL SCIENCES > Physics > Condensed Matter Physics
NATURAL SCIENCES > Chemistry > Physical Chemistry

Divisions:

Division of Physical Chemistry

Projects: