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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ershov A. E., Isaev I. L., Semina P. N., Markel V. A., Karpov S. V.
Заглавие : Effects of size polydispersity on the extinction spectra of colloidal nanoparticle aggregates
Место публикации : Phys. Rev. B: American Physical Society, 2012. - Vol. 85, Is. 4. - Ст.045421. - P. - ISSN 1098-0121, DOI 10.1103/PhysRevB.85.045421
Примечания : Cited References: 41. - This work was supported by grants from the following foundations of the Russian Federation: Presidium of RAS, OFN RAS, and SB RAS.
Предметные рубрики: METAL FRACTAL CLUSTERS
OPTICAL-PROPERTIES
ABSORPTION
NONLINEARITIES
COMPOSITES
SCATTERING
PARTICLES
SPHERES
GRAINS
Аннотация: We investigate the effect of particle polydispersity on the optical extinction spectra of colloidal aggregates of spherical metallic (silver) nanoparticles, taking into account the realistic interparticle gaps caused by layers of stabilizing polymer adsorbed on the metal surface (adlayers). The spectra of computer-generated aggregates are computed using two different methods. The coupled-multipole method is used in the quasistatic approximation and the coupled-dipole method beyond the quasistatics. The latter approach is applicable if the interparticle gaps are sufficiently wide relative to the particle radii. Simulations are performed for two different particle size distribution functions (bimodal and Gaussian), varying the number of particles per aggregate, and different distribution functions of the interparticle gap width. The strong influence of the latter factor on the spectra is demonstrated and investigated in detail.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Malakhovskii A. V., Sukhachev A. L., Leont'ev A. A., Gudim, I. A., Krylov A. S., Aleksandrovsky A. S.
Заглавие : Spectroscopic properties of Nd0.5Gd0.5Fe3(BO3)4 single crystal
Место публикации : J. Alloys Compd.: Elsevier, 2012. - Vol. 529. - P.38-43. - ISSN 0925-8388, DOI 10.1016/j.jallcom.2012.03.066
Примечания : Cited References: 51. - The work was supported by the Russian Foundation for Basic Researches grant 12-02-00026, by the Russian President Grants SS-1044.2012.2 and SS-4828.2012.2, by Ministry of Education and Science of Russian Federation (Contract 16.740.11.0150), by grant no. SFU.F12 and by Projects No. 28, 43 and No. 101 of SB RAS.
Предметные рубрики: SPECTRAL-LINE INTENSITIES
RARE-EARTH IONS
MAGNETIC-PROPERTIES
NDAL3(BO3)(4) NAB
OPTICAL-SPECTRA
LASER CRYSTAL
TRANSITIONS
ABSORPTION
ND3+
PR3+
Ключевые слова (''Своб.индексиров.''): magnetically ordered materials--rare earth alloys and compounds--transition metal alloys and compounds--optical properties
Аннотация: The polarized absorption spectra of trigonal single crystal Nd0.5Gd0.5Fe3(BO3)4 were measured in the spectral range 10,000–22,000 cm−1. The d–d and f–f transitions spectra were separated. The f–f transitions intensities were analyzed in terms of the Judd–Ofelt theory in a ferroborate with huntite structure for the first time, and the following parameters of the theory were obtained: Ω2 = 4.4 × 10−20 cm2, Ω4 = 8.04 × 10−20 cm2, and Ω6 = 8.25 × 10−20 cm2. The strengths, spontaneous emission probabilities, branching ratios, spectroscopic quality factor and excited state lifetime were calculated for transitions from the 4F3/2 state to 4IJ manifold. All the obtained spectroscopic characteristics were compared with those of alumoborates with the same crystal structure.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Slyusareva E. A., Sizykh A. G., Gerasimova M. A., Slabko V. V., Myslivets S. A.
Заглавие : Laser photolysis of fluorone dyes in a chitosan matrix
Место публикации : Quantum Electron.: Turpion LTD, 2012. - Vol. 42, Is. 8. - P.687-692. - ISSN 1063-7818, DOI 10.1070/QE2012v042n08ABEH014860
Примечания : Cited References: 32
Предметные рубрики: POLY(VINYL ALCOHOL) MATRIX
XANTHENE DYES
ROSE-BENGAL
FLUORESCENCE PROPERTIES
DELAYED FLUORESCENCE
ORGANIC-MOLECULES
TRIPLET-STATE
EXCITATION
ABSORPTION
PHOSPHORESCENCE
Ключевые слова (''Своб.индексиров.''): laser photolysis--fluorescein--dibromofluorescein--eosin y--erythrosin b--rose bengal--chitosan--photobleaching kinetics--two-step absorption
Аннотация: Kinetics of laser-induced photobleaching of fluorone dyes (fluorescein, dibromofluorescein, eosin Y, erythrosin B, Rose Bengal) is studied in a chitosan matrix. For all dyes the bleaching kinetics at the intensities of laser radiation 0.7 — 11.9 W cm-2 demonstrates quasi-monomolecular behaviour. The results are analysed using a kinetic model, based on the four-level (S0, S1, T1, Tn) scheme of the dye with chemically active triplet states taken into account. It is shown that the rate constants of the chemical reaction involving higher triplet states in the dyes studied amount to (3.9 — 18.6) × 106 s-1 and exceed the analogous values for the reaction involving the first lower triplet states by nine orders of magnitude. The rate of reaction involving the first triplet states appeared to be higher by one — two orders of magnitude than that in the case of higher triplet states involved because of low population of the latter. The possible mechanism of dye bleaching with participation of chitosan that consists in reduction of the dye to the leuco form by transfer of hydrogen from the chitosan matrix is discussed.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Slyusareva E. A., Tomilin F. N., Sizykh A. G., Tankevich E. Y., Kuzubov A. A., Ovchinnikov S. G.
Заглавие : The effect of halogen substitution on the structure and electronic spectra of fluorone dyes
Место публикации : Opt. Spectrosc.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2012. - Vol. 112, Is. 5. - P.671-678. - ISSN 0030-400X, DOI 10.1134/S0030400X12040194
Примечания : Cited References: 44. - This work was supported by the FTsP Kadry GK-P333 and by the Siberian Branch of the Russian Academy of Sciences (Integration project no. 2). We are grateful to the Joint Supercomputer Center of the Russian Academy of Sciences (Moscow) and to the Complex of High-Performance Computations of the IKIT of Siberian Federal University. E. A. Slyusareva acknowledges support from the German Academic Exchange Service and the Ministry of Education and Science of the Russian Federation (the program "Mikhail Lomonosov II") of scientific research at the University of Regensburg and in the Helmholtz Center in Berlin (Germany).
Предметные рубрики: POLARIZABLE CONTINUUM MODEL
BORIC-ACID GLASS
XANTHENE DYES
FLUORESCEIN DERIVATIVES
DELAYED FLUORESCENCE
EOSIN-Y
ABSORPTION
PHOSPHORESCENCE
TRANSITIONS
EXCITATION
Аннотация: By means of the B3LYP density functional method with the use of the polarized continuum model PCM, we have performed quantum-chemical computations of the electronic absorption and fluorescence spectra of fluorone dianions: fluorescein, dibromofluorescein, eosin, erythrosine, and Rose Bengal in vacuum and methanol. We have revealed conformational features of the structure of fluorone dianions (charge redistribution, changes in the bond lengths and angles between bonds) second by the halogen substitution, the transition from the ground state to an excited state, and the change of the solvent (vacuum-methanol). Absorption and fluorescence wavelengths, constant dipole moments, transition dipole moments, and oscillator strengths have been calculated. We have showed that, upon halogenation of fluorones, the absorption spectra are redshifted and the Stokes shift decreases, which is qualitatively consistent with experimental results.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ikonnikov D. A., Malakhovskii A. V., Sukhachev A. L., Temerov V. L., Krylov A. S., Bovina A. F., Aleksandrovsky A. S.
Заглавие : Spectroscopic properties of HoAl3(BO3)4 single crystal
Коллективы : Ministry of Education and Science of the Russian Federation for Siberian Federal University; Russian Foundation for Basic Research Grants [12-02-00026, 14-02-00219, 13-02-00825]; Russian President Grant [SS-2886.2014.2]; SB RAS Project [43]
Место публикации : Opt. Mater.: Elsevier Science, 2014. - Vol. 37. - P.257–261. - ISSN 0925, DOI 10.1016/j.optmat.2014.05.036. - ISSN 18731252 (eISSN)
Примечания : Cited References: 30. - The work was supported by Grant of the Ministry of Education and Science of the Russian Federation for Siberian Federal University, the Russian Foundation for Basic Research Grants 12-02-00026, 14-02-00219 and 13-02-00825, by the Russian President Grant SS-2886.2014.2, and by SB RAS Project No. 43.
Предметные рубрики: RARE-EARTH IONS
OPTICAL-PROPERTIES
Ho3+ IONS
ABSORPTION
INTENSITIES
EMISSION
GLASSES
SPECTRA
LUMINESCENCE
PARAMETERS
Ключевые слова (''Своб.индексиров.''): absorption--luminescence--holmium--huntite--judd-ofelt
Аннотация: The Judd–Ofelt theory has been applied to analyze absorption spectra of Ho3+ ion in HoAl3(BO3)4 measured in spectral range 300–700 nm at room temperature. The Judd–Ofelt spectroscopic parameters have been determined as: Ω2 = 18.87 x 10 -20 cm2, Ω4 = 17.04 x 10 -20 cm2, Ω6 = 9.21 x 10 -20 cm2. These parameters have been used to calculate radiative lifetimes and branching ratios of the luminescence manifolds. Three luminescent bands were found in the spectral range 450–700 nm ascribed to transitions from the 5F5, (5F4, 5S2) and 3K8 states to the ground state 5I8. Experimental intensities of these luminescence transitions were compared with those calculated by using Judd–Ofelt theory and the system of kinetic equations for populations of starting luminescing states. Probabilities of radiativeless transitions were evaluated from this comparison.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Malakhovskii A. V., Sukhachev A. L., Sokolov V. V., Kutsak T. V., Bondarev V. S., Gudim, I. A.
Заглавие : Magneto-optical activity of f–f transitions in ErFe3(BO3)4 and ErAl3(BO3)4 single crystals
Коллективы : Russian Foundation for Basic Researches [12-02-00026], President of Russia Grant [Nsh-2886.2014.2]
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2015. - Vol. 384. - P.255-265. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2015.02.051. - ISSN 1873-4766
Примечания : Cited References: 44. - The work was supported by the Russian Foundation for Basic Researches Grant 12-02-00026 and by the President of Russia Grant no. Nsh-2886.2014.2.
Предметные рубрики: CIRCULAR-DICHROISM SPECTRA
GREEN UP-CONVERSION
SPECTROSCOPIC PROPERTIES
OPTICAL-PROPERTIES
LASER
Er3+
ABSORPTION
GROWTH
IONS
GdFe3(BO3)4
Ключевые слова (''Своб.индексиров.''): magnetic circular dichroism--natural circular dichroism--rare earth ferroborates--rare earth alumoborates--electronic structure
Аннотация: Absorption, magnetic circular dichroism and natural circular dichroism spectra of ErFe3(BO3)4 and ErAl3(BO3)4 single crystals were measured as a function of temperature in the range of 90–293 K. It was found out that magneto-optical activity of the same f–f transitions in the studied crystals substantially differed and their temperature dependences did not follow the Curie–Weiss law in contrast to the properties of allowed transitions. The observed phenomena were accounted for by the nature of f–f transitions allowance. Properties of the transition 4I15/2→4S3/2 were studied in detail. In particular, the Zeeman splitting and the natural optical activity of the absorption lines composed of the transition were determined. The vibronic line with the very large natural optical activity was revealed and identified. Two nonequivalent Er3+ ion positions with the opposite chirality were found out in one of the excited states. Polarization properties of the 4I15/2→4S3/2 transition in the ErFe3(BO3)4 crystal have shown that the local symmetry of Er3+ ion in this crystal in the range of 90–293 K is lower than the D3 one. From the heat capacity measurements it was revealed, that the first order structural phase transition to lower symmetry occurred in ErFe3(BO3)4 at 433–439 K.Поглощение, магнитный циркулярный дихроизм и спектры природного кругового дихроизма монокристаллов ErFe3(BO3)4 и ErAl3(BO3)4 были измерены в зависимости от температуры в диапазоне 90-293 К. Было обнаружено, что по магнитооптической активности одни и те жеF-F переходы в исследованных кристаллах существенно отличаются и их температурные зависимости не следовать закону Кюри-Вейсса в отличие от свойств разрешенных переходов. Наблюдаемые явления были учтены по характеру F-Fпереходов. Свойства перехода 4I15 / 2 → 4S3 / 2 были детально изучены. В частности, расщепление Зеемана и явление естественной оптической активности линий поглощения, состоящих в переходе были полны решимости. Вибронная линия очень большой естественной оптической активности выявлена и идентифицирована. Две неэквивалентных позиций ионовEr3 + с противоположной хиральности были найдены в одном из возбужденных состояний. Поляризационные свойства 4I15 / 2 → 4S3 / 2 перехода в ErFe3(BO3)4 кристалла показали, что локальная симметрия ионов Er3 + в этом кристалле в диапазоне 90-293 К ниже, чем D3. Из измерений теплоемкости Было обнаружено, что структурный фазовый переход первого типа к более низкой симметрии произошел в ErFe3(BO3) 4 при 433-439 К. Ключевые слова: Магнитный круговой дихроизм; Природные круговой дихроизм; Редкоземельные ферроборатов; Редкоземельныеalumoborates; Электронная структура; 44 источника.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lyapina A. A., Maksimov D. N., Pilipchuk A. S., Sadreev A. F.
Заглавие : Bound states in the continuum in open acoustic resonators
Место публикации : J. Fluid Mech. - 2015. - Vol. 780. - P.370-387. - ISSN 0022-1120, DOI 10.1017/jfm.2015.480
Примечания : Cited References: 48. - This work has been supported by Russian Science Foundation through grant 14-12-00266.
Предметные рубрики: TRAPPED MODES
FANO RESONANCES
COMPLEX RESONANCES
PARALLEL PLATES
SIDE-BRANCHES
WAVE-GUIDES
ABSORPTION
TRANSPORT
CHANNELS
SYSTEM
Ключевые слова (''Своб.индексиров.''): aeroacoustics--noise control--wave scattering
Аннотация: We consider bound states in the continuum (BSCs) or embedded trapped modes in two- and three-dimensional acoustic axisymmetric duct-cavity structures. We demonstrate numerically that, under variation of the length of the cavity, multiple BSCs occur due to the Friedrich-Wintgen two-mode full destructive interference mechanism. The BSCs are detected by tracing the resonant widths to the points of the collapse of Fano resonances where one of the two resonant modes acquires infinite life-time. It is shown that the approach of the acoustic coupled mode theory cast in the truncated form of a two-mode approximation allows us to analytically predict the BSC frequencies and shape functions to a good accuracy in both two and three dimensions. © 2015 Cambridge University Press.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sandalov I. S., Zamkova N. G., Zhandun V. S., Tarasov I. A., Varnakov S. N., Yakovlev I. A., Solovyov L. A., Ovchinnikov S. G.
Заглавие : Effect of electron correlations on the Fe3Si and α- FeSi2 band structure and optical properties
Коллективы : Russian Fund of Basic Research [14002-00186, 13-02-01265]; President of Russia Grants [2886.2014.2, 924.2014.2]
Место публикации : Phys. Rev. B: American Physical Society, 2015. - Vol. 92, Is. 20. - Ст.205129. - ISSN 1098-0121, DOI 10.1103/PhysRevB.92.205129. - ISSN 1550-235X(eISSN)
Примечания : Cited References:69. - The theoretical part of this work was supported by Russian Fund of Basic Research, Grant No. 14002-00186 and the President of Russia Grants No. 2886.2014.2 and No. 924.2014.2 for support of Leading Scientific School. The calculations were performed with the computer resources of NRC "Kurchatov Institute" (ui2.computing.kiae.ru). The experimental work was supported by Russian Fund of Basic Research, Grant No. 13-02-01265. I.S. thanks A. Ruban for useful discussion.
Предметные рубрики: DENSITY-FUNCTIONAL THEORY
TOTAL-ENERGY CALCULATIONS
AUGMENTED-WAVE METHOD
BASIS-SET
METALS
ABSORPTION
EMISSION
SURFACES
ALLOYS
LAYERS
Аннотация: We use the Vienna ab initio simulation package (vasp) for evaluation of the quasiparticle spectra and their spectral weights within Hedin's GW approximation (GWA) for Fe3Si and α-FeSi2 within the non-self-consistent one-shot approximation G0W0 and self-consistent scGWA with the vertex corrections in the particle-hole channel, taken in the form of two-point kernel. As input for G0W0, the band structure and wave functions evaluated within the generalized gradient corrected local-density approximation to density functional theory (GGA) have been used. The spectral weights of quasiparticles in these compounds deviate from unity everywhere and show nonmonotonic behavior in those parts of bands where the delocalized states contribute to their formation. The G0W0 and scGWA spectral weights are the same within 2%–5%. The scGWA shows a general tendency to return G0W0 bands to their GGA positions for the delocalized states, while in the flat bands it flattens even more. Variable angle spectroscopic ellipsometry measurements at T=296 K on grown single-crystalline ∼50-nm-thick films of Fe3Si on n-Si(111) wafer have been performed in the interval of energies ω∼(1.3–5) eV. The comparison of G0W0 and scGW theory with experimental real and imaginary parts of permittivity, refractive index, extinction and absorption coefficients, reflectivity, and electron energy loss function shows that both G0W0 and scGW qualitatively describe experiment correctly, the position of the low-energy peaks is described better by the scGW theory, however, its detailed structure is not observed in the experimental curves. We suggest that the angle-resolved photoemission spectroscopy experiments, which can reveal the fine details of the quasiparticle band structure and spectral weights, could help to understand (i) if the scGWA with this type of vertex correction is sufficiently good for description of these iron silicides and, possibly, (ii) why some features of calculated permittivity are not seen in optical experiments.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bouznik V. M., Morozov E. V., Avilova I. A., Volkov V. I.
Заглавие : NMR applications for polymer composite materials moisture uptake investigation
Место публикации : Appl. Magn. Reson.: Springer, 2016. - Vol. 47, Is. 3. - P.321-334. - ISSN 09379347 (ISSN), DOI 10.1007/s00723-015-0748-2
Примечания : Cited References: 41. - This research was performed with the financial support of Russian Foundation for Basic Research (project no. 14-29-10178 ofi_m).
Предметные рубрики: FIELD GRADIENT NMR
REINFORCED EPOXY COMPOSITES
WATER SELF-DIFFUSION
TRANSPORT
GLASS
SYSTEM
SPECTROSCOPY
TEMPERATURE
ABSORPTION
ADHESIVE
Аннотация: The 1H nuclear magnetic resonance (NMR) spectroscopy, NMR imaging, and pulsed field gradient NMR (PFG NMR) were applied for comparative study of moisture–polymer composite materials (PCM) interaction. The water uptake in PCM reinforced by aramid and carbon fibers was measured by NMR spectroscopy techniques. The aramid fiber-reinforced PCM absorbs water more intensively compared with PCM reinforced by carbon fiber, but both of them are retaining water inside of pores without formation of chemical bonds. Using NMR imaging the spatial distribution of water absorbed was visualized; preferable water pathways and influence of surface treatment on water-resistant properties were revealed. It was found that the surface rough treatment sufficiently improves the water absorption, but penetration of water molecules is still occurring only through the surfaces and it happens within a thin layer. PFG NMR technique revealed influence of pore structure on moisture–PCM interaction; it was found that additionally to strong hydrophobic properties of carbon fiber, the smaller total volume of pores sufficiently decrease the water uptake. Results achieved in this work demonstrate efficiency of NMR methods applied all together for investigation of PCM, and information obtained is practically important when designing advanced PCM with required properties. © 2016, Springer-Verlag Wien.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Edelman I. S., Sokolov A. E., Zabluda V. N., Shubin A. A., Martyanov O. N.
Заглавие : Magnetic circular dichroism analysis of crude oil
Коллективы : Russian Federation [NSh-2886.2014.2]; Kirensky Institute of Physics (Siberian Branch, Russian Academy of Sciences) [V.44.1.15]; Boreskov Institute of Catalysis (Siberian Branch, Russian Academy of Sciences) [V.44.1.15]
Место публикации : J. Struct. Chem.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 57, Is. 2. - P.382-389. - ISSN 0022-4766, DOI 10.1134/S0022476616020207. - ISSN 1573-8779(eISSN)
Примечания : Cited References:33. - The work was carried out with the partial support of the grant of the President of the Russian Federation (NSh-2886.2014.2), and in the frameworks of the base budget financing of Kirensky Institute of Physics and Boreskov Institute of Catalysis (Siberian Branch, Russian Academy of Sciences) (V.44.1.15.).
Предметные рубрики: Near-UV/visible spectroscopy
Electron-spin-resonance
Asphaltene dispersions
Single-crystals
Absorption
VO2+
EPR
FLuorescence
Aggregation
Absorbency
Ключевые слова (''Своб.индексиров.''): magnetic circular dichroism (mcd)--mcd spectroscopy--absorption spectroscopy of oil
Аннотация: Optical and magneto-optical properties of solutions of crude oil of different origin (i.e., taken from different fields) are studied in the visible and near-UV region of optical emission. Magnetic circular dichroism (MCD) spectra of oil are obtained in the vicinity of wavelengths of ~410 nm, 533 nm, and 576 nm. It is demonstrated that the intensity of the MCD signal depends on the origin of crude oil, and it is proportional to the oil concentration in the solution. The comparison of the magneto-optical spectroscopy data with the chemical composition of samples allows us to conclude that the observed magneto-optical activity is determined by the presence of VO2+ complexes in the oil samples studied. The revealed magneto-optical activity of conventional oil can form a basis of a new method for the analysis of the composition and properties of oil of different origin.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Malakhovskii A. V., Sukhachev A. L., Leont'ev A. A., Temerov V. L.
Заглавие : Magnetic and natural optical activity of f–f transitions in multiferroic Nd0.5Gd0.5Fe3(BO3)4
Коллективы : Council on Grants from the President of the Russian Federation for the State Support of Leading Scientific Schools [NSh-2886.2014.2]; Russian Foundation for Basic Research [16-02-00273]
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 58, Is. 5. - P.952-958. - ISSN 1063-7834, DOI 10.1134/S1063783416050152. - ISSN 1090-6460(eISSN)
Примечания : Cited References:29. - This study was supported by the Council on Grants from the President of the Russian Federation for the State Support of Leading Scientific Schools (grant no. NSh-2886.2014.2) and the Russian Foundation for Basic Research (project no. 16-02-00273).
Предметные рубрики: Circular-dichroism spectra
Magnetooptical properties
Single-crystal
Absorption
Ions
NdFe3(BO3)4
Nd3+
Pr3+
Ho3+
Аннотация: Spectra of absorption, magnetic circular dichroism, and natural circular dichroism of the f–f transitions 4I9/2 → 4F3/2, 2H9/2 + 4F5/2, 4S3/2 + 4F7/2, 2G7/2 + 4G5/2, 2K13/2 + 4G7/2, and 4G9/2 in the Nd3+ ions in the Nd0.5Gd0.5Fe3(BO3)4 crystal have been measured as a function of the temperature in the interval of 90–300 K. Temperature dependences of the magneto-optical activity (MOA) and natural optical activity (NOA) of the transitions have been obtained. It has been found that, in contrast to allowed transitions, the temperature dependence of the MOA of the f–f transitions does not obey the Curie–Weiss law and the NOA depends on temperature. The NOA of some transitions changes the sign with variation in temperature. These phenomena have been explained by the presence of three contributions to the allowance of the f–f transitions, which lead to three contributions of different signs to the MOA and NOA. The range of the MOA of the f–f transitions in the Nd3+ ion has been predicted theoretically and confirmed experimentally.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Gizhevskii B. A., Sukhorukov Y. P., Ermakov A. E., Uimin M. A., Kozlov E. A., Kotov Y. A., Bagazeev A. V.
Заглавие : Specific features of the electronic structure and optical spectra of nanoparticles with strong electron correlations
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2007. - Vol. 49, Is. 6. - P1116-1120. - ISSN 1063-7834, DOI 10.1134/S1063783407060169
Примечания : Cited References: 18. - This study was supported by the Russian Academy of Sciences within the program "Strong Electron Correlations", the Integration Project of the Siberian Division–Ural Division of the Russian Academy of Sciences (project no. 74), the Federal Agency for Science and Innovation (contract no. 02.434.11.7048), the Russian Foundation for Basic Research (project no. 06-03-32943), and the Branch of General Physics and Astronomy of the Russian Academy of Sciences and the Presidium of the Ural Division of the Russian Academy of Sciences within the program "New Materials and Structures"
Предметные рубрики: CUO
ABSORPTION
STATES
Аннотация: Analysis of the experimental optical spectra of CuO nanoparticles with the electronic structure characterized by strong electron correlations has revealed the appearance of unusual states inside the band gap. The intragap states an the specific features of the electronic structure of CuO nanoparticles are discussed in the framework of the generalized tight-binding method previously developed for describing the electronic structure of superconducting cuprates.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zabluda V. N., Ovchinnikov S. G., Potseluliko A. M., Kharlamova S. A.
Заглавие : Optical properties and electronic structure of rare-earth ferroborates
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 3. - P489-494. - ISSN 1063-7834, DOI 10.1134/1.1884710
Примечания : Cited References: 19. - This work was supported by the Russian Foundation for Basic Research (project no. 03-02-16268) and the program of the Department of Physical Sciences of the Russian Academy of Sciences "Strongly Correlated Electrons"
Предметные рубрики: TRIGONAL GDFE3(BO3)(4)
MAGNETIC-PROPERTIES
BAND-STRUCTURE
FEBO3
ABSORPTION
Аннотация: The optical absorption spectra of single-crystal ferroborate GdFe3(BO3)(4) and GdFe2.1Ga0.9(BO3)(4) are measured and interpreted. It is found that the absorption edge and the absorption bands A, B, and C observed below the edge are close to those for FeBO3. A many-electron model of the band structure of GdFe3(BO3)(4) is suggested including strong electron correlations between the iron d states. It is shown that GdFe3(BO3)(4) has a charge-transfer dielectric gap. A rise in pressure is predicted to result in a crossover between the high-spin and low-spin states of the Fe ion, collapse of the magnetic moment, a weakening of Coulomb correlations, an abrupt reduction in the energy gap, and an insulator-semiconductor transition. (c) 2005 Pleiades Publishing, Inc.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivchenko E. L., Voronov M. M., Erementchouk M. V., Deych L. I., Lisyansky A. A.
Заглавие : Multiple-quantum-well-based photonic crystals with simple and compound elementary supercells
Место публикации : Phys. Rev. B: AMERICAN PHYSICAL SOC, 2004. - Vol. 70, Is. 19. - Ст.195106. - ISSN 1098-0121, DOI 10.1103/PhysRevB.70.195106
Примечания : Cited References: 33
Предметные рубрики: EXCITON POLARITONS
DIELECTRIC MEDIUM
OPTICAL LATTICES
BRAGG STRUCTURES
BAND-STRUCTURES
PERIODIC-BRAGG
REFLECTION
ABSORPTION
SPECTRA
ARRAYS
Ключевые слова (''Своб.индексиров.''): article--crystal--crystal structure--elementary particle--light scattering--mathematical analysis
Аннотация: Exciton polaritons in one-dimensional photonic crystals based on multiple quantum well structures are investigated. The effects due to interplay between resonant interaction of light with quantum well excitons, and light scattering from well-barrier interface, are elucidated. Polariton dispersion equations and reflection spectra in structures with two wells in an elementary supercell of the periodic structure are studied. Several examples of different compound elementary supercells are considered. Special attention is paid to structures with the period or the distance between quantum wells satisfying the resonance Bragg condition. Such structures are characterized by a presence of a larger-than-usual polariton stop band. It is shown that in structures with a complex elementary supercell, the width of such a stop band can be significantly enhanced in comparison to that in simple structures.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavriliuk A. G., Trojan I. A., Ovchinnikov S. G., Lyubutin I. S., Sarkisyan V. A.
Заглавие : The mechanism of suppression of strong electron correlations in FeBO3 at high pressures
Разночтения заглавия :авие SCOPUS: The mechanism of suppression of strong electron correlations in FeBO 3 at high pressures
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2004. - Vol. 99, Is. 3. - P566-573. - ISSN 1063-7761, DOI 10.1134/1.1809686
Примечания : Cited References: 18
Предметные рубрики: MAGNETIC COLLAPSE
TRANSITION
SPECTRA
ABSORPTION
STATE
Ключевые слова (''Своб.индексиров.''): crystal structure--high pressure effects--light absorption--parameter estimation--phase transitions--spectrum analysis--crystal field--electron correlations--generalized tight binding method--hybridization--iron compounds
Аннотация: The optical absorption spectra of iron borate (FeBO3) are measured at high pressures up to P = 82 GPa. A mechanism of suppression of strong electron correlations is proposed within the framework of the generalized tight binding method, which leads to the experimentally observed magnetic, electronic, and structural phase transitions. Taking into account peculiarities of the crystal structure of FeBO3 and the strong s-p hybridization of boron and oxygen, it is established that, as the distance between ions varies with increasing pressure, the crystal field parameter begins to play a decisive role in the electron transitions, while the influence of the d band broadening is negligibly small. Parameters of the theory are calculated as functions of the pressure. (C) 2004 MAIK "Nauka / Interperiodica".
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Popov M. A.
Заглавие : On the coordinate of a singular point of time correlation functions for the system of nuclear magnetic moments of a crystal
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2003. - Vol. 97, Is. 1. - P78-84. - ISSN 1063-7761, DOI 10.1134/1.1600799
Примечания : Cited References: 22
Предметные рубрики: DIPOLAR FLUCTUATION SPECTRUM
FREE-INDUCTION DECAY
CROSS-RELAXATION
DOUBLE-RESONANCE
SPIN SYSTEMS
NMR-SPECTRA
LINE SHAPE
IRREVERSIBILITY
ABSORPTION
CAF2
Ключевые слова (''Своб.индексиров.''): absorption spectroscopy--barium compounds--crystallography--lattice constants--magnetic fields--nuclear magnetic resonance--absorption spectrum--dipole-dipole interaction--magnetic field directions--nuclear magnetic moments--magnetic moments
Аннотация: The hypothesis concerning the existence of singular points on the imaginary time axis for a correlation function of a system with the dipole-dipole interaction of nuclear spins of a crystal is verified. Within the framework of the self-consistent fluctuating field theory taking into account the principal corrections related to the correlation of local fields, a result for this coordinate is obtained in terms of the ratios of lattice sums. Experimental values of this coordinate are calculated from the wings of the nuclear magnetic resonance absorption spectrum of a BaF2 crystal for the magnetic field directions along the three crystallographic axes. Good agreement of the theoretical and experimental results justifies this hypothesis. (C) 2003 MAIK "Nauka / Interperiodica".
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Deich L. I.
Заглавие : Far-infrared attenuation in glasses
Разночтения заглавия :авие SCOPUS: Far-infrared attenuation in glasses
Место публикации : Phys. Rev. B. - 1994. - Vol. 49, Is. 1. - P.109-113. - ISSN 0163-1829, DOI 10.1103/PhysRevB.49.109
Примечания : Cited References: 29
Предметные рубрики: VITREOUS SILICA
TEMPERATURE
MODEL
LOCALIZATION
ABSORPTION
SOLIDS
STATES
Аннотация: The influence of quasilocal vibrations on the far-infrared spectra of glasses is investigated under the supposition that the quasilocal vibrations are directly inactive in the attenuation. It is shown that taking into account phonon-quasilocal-vibration coupling and both medium- and short-range structure of the inhomogeneities of a photon-phonon coupling parameter can give rise to an attenuation curve similar to one observed for a-SiO2 and related materials.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arkhipkin V. G., Myslivets S. A.
Заглавие : One- and two-dimensional Raman-induced diffraction gratings in atomic media
Место публикации : Phys. Rev. A. - 2018. - Vol. 98, Is. 1. - Ст.013838. - ISSN 2469-9926, DOI 10.1103/PhysRevA.98.013838. - ISSN 2469-9934(eISSN)
Примечания : Cited References: 37
Предметные рубрики: ELECTROMAGNETICALLY INDUCED TRANSPARENCY
COLD ATOMS
ABSORPTION
Аннотация: We propose and analyze an efficient scheme for the one- and two-dimensional atomic gratings based on periodic spatial modulation of the Raman gain and dispersion, which we name the Raman-induced diffraction gratings (RIDGs). There are fundamentally different from those based on electromagnetically induced transparency. As the probe field propagates along the direction normal to the standing pump wave, it can be effectively diffracted into high-order directions. The grating is a hybrid grating, i.e. it represents a mixture of amplitude and phase gratings. We identify the conditions when all high-order diffractions are amplified. In addition, we also show that diffraction of a probe field could be dynamically controlled using an additional laser field. With its help, it is possible to suppress or amplify diffraction beams. The RIDGs can be considered as all-optical multibeam splitters with amplification.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vyunishev A. M., Bikbaev R. G., Svyakhovskiy, Sergey E., Timofeev I. V., Pankin P. S., Evlashin, Stanislav A., Vetrov S. Ya., Myslivets S. A., Arkhipkin V. G.
Заглавие : Broadband Tamm plasmon polariton
Коллективы : Russian Foundation for Basic Research (RFBR) [18-32-00053]; Russian Federation [MK-2761.2019.2]
Место публикации : J. Opt. Soc. Am. B. - 2019. - Vol. 36, Is. 8. - P.2299-2305. - ISSN 0740-3224, DOI 10.1364/JOSAB.36.002299. - ISSN 1520-8540(eISSN)
Примечания : Cited References: 50. - Russian Foundation for Basic Research (RFBR) (18-32-00053); Grant of the President of the Russian Federation (MK-2761.2019.2).
Предметные рубрики: PHOTONIC CRYSTAL
OPTICAL-CONSTANTS
PERFECT ABSORBER
ABSORPTION
Аннотация: A broadband Tamm plasmon polariton localized at the interface between the Bragg mirror and a thin metallic layer has been theoretically and experimentally investigated. The possibility of a localized state formation has been demonstrated and energy coefficients at the Tamm plasmon polariton wavelength have been predicted in the framework of the coupled mode theory. The metallic layer material and thickness corresponding to the maximum coupling between the incident radiation and the Tamm plasmon polariton has been determined. Experimental reflectance and transmittance spectra of the structure consisting of the Bragg mirror and chromium layers of different thicknesses have been measured. The analysis of the energy spectra shows the existence of the wavelength range with the near-unity absorption coefficient inside the Bragg mirror bandgap. The use of chromium as a metal results in the broadband Tamm plasmon polariton excitation. It is demonstrated that the experimental data is in a good agreement with the calculation.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Handunkanda, Sahan U., Curry, Erin B., Voronov V. N., Hancock, Jason N.
Заглавие : Infrared lattice dynamics in negative thermal expansion material in single-crystal ScF3
Место публикации : J. Phys.: Condens. Matter. - 2020. - Vol. 32, Is. 3. - Ст.035403. - ISSN 0953-8984, DOI 10.1088/1361-648X/ab4955. - ISSN 1361-648X(eISSN)
Примечания : Cited References: 49. - Work at the University of Connecticut is supported by National Science Foundation Award No. DMR-1506825
Предметные рубрики: LONGITUDINAL-OPTIC MODES
TEMPERATURE-DEPENDENCE
ABSORPTION
Аннотация: Simple cubic 'open' perovskite ScF3 stands out among trifluoride materials in its large, isotropic negative thermal expansion (NTE), but also its proximity of its zero-temperature state to a structural phase transition. Here we report a temperature- and frequency-dependent lattice dynamical study of Brillouin zone center lattice excitations of single crystals of ScF3 using infrared reflectivity measurements. In addition to quantifying the mode strengths and energies in single crystals of this interesting material, we also find strong evidence for multiphonon absorption processes which excite the zone-edge incipient soft modes associated with NTE and the structural quantum phase transition. In this way, we identify an optically-allowed pathway to excite soft modes provides a means to athermally populate modes associated with NTE in ScF3.
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