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Dolinnyi A.I.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry
Journal of Physical Chemistry C

Using a generalized multiparticle Mie theory, we calculated the optical properties of gold nanoparticle (Au NP) pairs of 8-80 nm in diameter (D) and 0.1-120 nm in interparticle gap (s) under typical experimental conditions: an unpolarized incident light and random orientation of the pairs in space. By analyzing the extinction spectra of coupled spheres, three ranges of interparticle separations (long, middle and short) with different plasmon coupling regimes were distinguished. For long interparticle distances, a single plasmon peak in the spectrum at wavelength λp red-shifts exponentially relative to that of an isolated particle at wavelength λ0 as a function of x = s/D: Δλ/λ0 = (λp - λ0)/λ0 = a exp(-x/t), with a decay constant (t = 0.19) being nearly independent of nanoparticle diameters at D < 50 nm. Stronger shifts (0.04 < a < 0.08) are observed for 30-60 nm Au NPs. In the middle distance range (0.02 < s/D < (s/D)split), the extinction spectra of dimers have two plasmon peaks: transverse and longitudinal. The shift of long-wavelength peak can be reasonably approximated by the equation Δλ/λ0 = a0 + a1 exp(-x/t1), where the parameters a1 (= 0.352) and t1 (= 0.032) do not depend on the nanoparticle sizes, and a0 increases with particle size. The boundary between the long and middle interparticle distance ranges, (s/D)split, strongly varies with the Au NP diameter. At s/D < 0.02, the birth and evolution of third plasmon peak that is located between the transverse and longitudinal peaks has a strong effect upon the spectral properties of closely coupled NPs. Now the fractional shift of the longitudinal peak obeys the equation Δλ/λ0 = a0 + a1 exp(-x/t1) + a2 exp(-x/t2), where t2 = 0.004 and a2 = 0.643. The constancy of coefficients ai and ti for Au NPs of different sizes means that the fractional shifts of plasmon resonances of coupled pairs corrected by parameter a0 have to fall on a common curve. The obtained results clearly point that the Au NPs pairs can be used as the highly sensitive instruments to measure both absolute distances and their changes in the nanometric range of lengths. © 2015 American Chemical Society. Source

Kulova T.L.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry
Russian Journal of Electrochemistry

The main principles of operation of modern lithium-ion batteries and the modern trends in development of new-generation batteries are described. © 2013 Pleiades Publishing, Ltd. Source

Gokhshtein A.Y.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry
Journal of Solid State Electrochemistry

Contrary to some recent publications, the trivial definition of the surface charge density q0Q/A does not give any information about the charge Q and area A. Therefore this definition cannot be used as a "simple check," rejecting results of electrochemical experiments where the values Q and A are the independent variables. Experimental confirmation and practical applications can be the two selfcontained checks for the equations of solid-state electrocapillarity. Along with thermodynamics, the kinetic aspect is important here since the charge and area can oscillate in the large frequency range. Cycling the surface charge gives the three different contributions to the alternating surface tension of solids, corresponding to the double layer charging, reversible chemisorption, and discrete transitions closed within the rigid surface layer. The derivative of the charge density with respect to elastic deformation represents chemisorption and can be decreased to negligibly small value at the point of zero charge by increasing the frequency. On the base of the solid-state electrocapillarity, the dependence between the adsorption energy and elastic deformation was measured for the first time. It was thus found that stretching reinforces the bonding of hydrogen to the platinum surface. Acting inside the rigid surface monolayer, the alternating surface tension of solids is an independent tool in solving some complex problems of electrochemistry and solid-state physics. Two consecutive transitions are discovered on platinum instead of two coexistent hydrogen states which earlier were associated with two waves of the charging current. There are three consecutive hydrogen states separated along the potential axis by transitions from one state to another. Similar surface transitions are observed also on iridium, rhodium, and palladium. The number of transitions coincides with the number of finite radial nodes of the wave functions formed by d-electrons of these metals. © Springer-Verlag 2012. Source

Krishtalik L.I.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry
Biochimica et Biophysica Acta - Bioenergetics

A low static dielectric permittivity of proteins causes the low reorganization energies for the charge transfer reactions inside them. This reorganization energy does not depend on the pre-existing intraprotein electric field. The charge transferred inside the protein interacts with its aqueous surroundings; for many globular proteins, the effect of this surroundings on the reorganization energy is comparable with the effect of reorganization of the protein itself while for the charge transfer in the middle of membrane the aqueous phase plays a minor role. Reorganization energy depends strongly on the system considered, and hence there is no sense to speak on the "protein reorganization energy" as some permanent characteristic parameter. We employed a simple algorithm for calculation of the medium reorganization energy using the numerical solution of the Poisson-Boltzmann equation. Namely, the reaction field energy was computed in two versions - all media having optical dielectric permittivity, and all the media with the static one; the difference of these two quantities gives the reorganization energy. We have calculated reorganization energies for electron transfer in cytochrome c, various ammine-ruthenated cytochromes c, azurin, ferredoxin, cytochrome c oxidase, complex of methylamine dehydrogenase with amicyanin, and for proton transfer in α-chymotrypsin. It is shown that calculation of the medium reorganization energy can be a useful tool in analysis of the mechanisms of the charge transfer reactions in proteins. © 2011 Elsevier B.V. All rights reserved. Source

Belyaev A.V.,RAS Frumkin Institute of Physical Chemistry and Electrochemistry | Vinogradova O.I.,RWTH Aachen
Physical Review Letters

We give a general theoretical description of electro-osmotic flow at striped superhydrophobic surfaces in a thin double layer limit, and derive a relation between the electro-osmotic mobility and hydrodynamic slip-length tensors. Our analysis demonstrates that electro-osmotic flow shows a very rich behavior controlled by slip length and charge at the gas sectors. In the case of an uncharged liquid-gas interface, the flow is the same or inhibited relative to the flow in a homogeneous channel with a zero interfacial slip. By contrast, it can be amplified by several orders of magnitude provided slip regions are uniformly charged. When gas and solid regions are oppositely charged, we predict a flow reversal, which suggests the possibility of a huge electro-osmotic slip even for electroneutral surfaces. On the basis of these observations we suggest strategies for practical microfluidic devices. © 2011 American Physical Society. Source

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