Publications by authors named "Alexei F Privalov"

Sulfonated, cross-linked porous polymers are promising frameworks for aqueous high-performance electrolyte-host systems for electrochemical energy storage and conversion. The systems offer high proton conductivities, excellent chemical and mechanical stabilities, and straightforward water management. However, little is known about mass transport mechanisms in such nanostructured hosts.

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We use H and O NMR static field gradient diffusometry to measure self-diffusion coefficients of protons () and oxygens () in Nafion 212 with various hydration levels (λ = 4-18). For all samples and both nuclei, we obtain activation energies () of ≈0.19 eV.

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Many technological applications like inkjet printing, coating, or cooling processes rely on the evaporation of sessile droplets. Regarding liquid mixtures, the understanding of the underlying physics is still incomplete and process optimization requires trial and error. Our main goal is to establish a novel method in this field, one-dimensional magnetic resonance microscopy, to investigate the evaporation of sessile binary mixture droplets in the microliter range.

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Field Cycling (FC) H nuclear magnetic resonance (NMR) relaxometry was applied to study dynamics in Nafion NR 212 in the temperature range from 300 K to 190 K and water content of λ = 8.2. The sensitive time window of FC was extended up to eight decades using the temperature-frequency superposition principle and master curve.

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The sulfonated polynaphthoyleneimide polymer (co-PNIS70/30) was prepared by copolymerization of 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODAS) and 4,4'-methylenebisanthranilic acid (MDAC) with ODAS/MDAC molar ratio 0.7/0.3.

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A recent measurement of the hyperfine splitting in the ground state of Li-like ^{208}Bi^{80+} has established a "hyperfine puzzle"-the experimental result exhibits a 7σ deviation from the theoretical prediction [J. Ullmann et al., Nat.

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The paper reviews recent progress in field cycling (FC) NMR instrumentation and its application to solid state physics. Special emphasis is put on our own work during the last 15years on instrumentation, theory and applications. As far as instrumentation is concerned we report on our development of two types of electronical FC relaxometers, a mechanical FC relaxometer and a combination of FC and one-dimensional microimaging.

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We use (7)Li NMR to study lithium ion dynamics in a (Li2S)-(P2S5) glass. In particular, it is shown that a combination of (7)Li field-cycling relaxometry and (7)Li stimulated-echo experiments allows us to cover a time window extending over 10 orders of magnitude without any gaps. While the (7)Li stimulated-echo method proved suitable to measure correlation functions F2(t) of lithium ion dynamics in solids in recent years, we establish the (7)Li field-cycling technique as a versatile tool to ascertain the spectral density J2(ω) of the lithium ionic motion in this contribution.

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A general theory of field dependent spin-lattice relaxation for nuclei of the spin quantum number 1/2 (1H, 19F, 13C) caused by dipole-dipole interactions with neighboring quadrupolar nuclei (nuclei possessing a quadrupolar moment) is presented. The theory is valid for arbitrary motional conditions and should be treated as a quadrupolar counterpart of the paramagnetic relaxation enhancement theory. When the energy level splitting of the dipolar spin (I=1/2) matches one of the transition frequencies of the quadrupolar nuclei one can observe a local enhancement of the dipolar spin relaxation (referred to as "quadrupolar peaks").

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A new concept for an energy efficient electromagnet for fast field cycling NMR applications as well as its construction and first test results are presented. The magnet, which provides a rectangular sample space of 17 x 25 mm, has an iron yoke and pole pieces optimised with respect to the B(0) homogeneity. The maximum field is 0.

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