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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Deich L. I.
Заглавие : Low-frequency raman-scattering in glasses
Разночтения заглавия :авие SCOPUS: Low-frequency Raman scattering in glasses
Место публикации : Phys. Rev. B. - 1995. - Vol. 51, Is. 13. - P.8131-8139. - ISSN 0163-1829, DOI 10.1103/PhysRevB.51.8131
Примечания : Cited References: 32
Предметные рубрики: AMORPHOUS SOLIDS
VITREOUS SILICA
THERMAL-CONDUCTIVITY
LIGHT-SCATTERING
TEMPERATURE
STATES
MODES
HEAT
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Two-particle spin-singlet excitations in coupled spin-1/2 antiferromagnetic alternating chains
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2001. - Vol. 13, Is. 14. - P.3403-3410. - ISSN 0953-8984, DOI 10.1088/0953-8984/13/14/313
Примечания : Cited References: 14
Предметные рубрики: MAGNETIC-PROPERTIES
LIGHT-SCATTERING
CUGEO3
S=1/2
Ключевые слова (''Своб.индексиров.''): antiferromagnetic materials--approximation theory--chemical bonds--electron transport properties--monte carlo methods--particles (particulate matter)--quantum theory--thermal effects--antiferromagnetic alternating chains--excitation spectrum--interchain exchange--mean-field approximation--quantum monte carlo method--singlet gaps--spin-singlet excitations--energy gap
Аннотация: The spectrum of the two-particle spin-singlet (DeltaS(z) = 0, +/-1) excitations of a weakly coupled antiferromagnetic spin-1/2 alternating (J(1) +/- delta) chain is calculated using a mean-field approximation for the interchain exchange (J(2)) by the quantum Monte Carlo method. The bandwidth change of these excitations, the mass gaps in the singlet-singlet excitation spectrum, the top boundaries of the bands and the velocities of these excitations are estimated as functions of the alternating bond delta. The temperatures at which the singlet gaps close are determined.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Vtyurin A. N., Bulou A., Voronov V. N.
Заглавие : Raman spectra and phase transitions in the Rb2KScF6 elpasolite
Коллективы : Russian-CIS-Baltic-Japanese symposium on ferroelectricity
Место публикации : Ferroelectrics: Taylor & Francis LTD, 2003. - Vol. 284. - P221-238. - ISSN 0015-0193, DOI 10.1080/00150190390204709
Примечания : Cited References: 13
Предметные рубрики: LIGHT-SCATTERING
OPTICAL PHONONS
MODE
Ключевые слова (''Своб.индексиров.''): rb2kscf6--phase transitions--raman scattering--soft modes
Аннотация: Raman spectra of Rb2KScF6 elpasolite crystal have been studied in a wide temperature range, including two transition points: from cubic to tetragonal, and then-to the monoclinic phase. For the first time both for this crystal and for fluoride elpasolites in general soft modes restoration has been found below transition points; in agreement with selection rules a splitting of degenerate modes has been observed as well both for lattice vibrations and internal modes of ScF6 octahedrons. Parameters of Raman lines have been quantitatively analyzed and found in good agreement with known thermodynamic characteristics of these transitions; in particular, lines widths are shown to be determined by tree-phonons anharmonic interactions. A wide region of pretransitional fluctuations was found above the upper transition point.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Markel V. A., Pustovit V. N., Karpov S. V., Obuschenko A. V., Gerasimov V. S., Isaev I. L.
Заглавие : Electromagnetic density of states and absorption of radiation by aggregates of nanospheres with multipole interactions
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2004. - Vol. 70, Is. 5. - Ст.54202. - ISSN 1098-0121, DOI 10.1103/PhysRevB.70.054202
Примечания : Cited References: 81
Предметные рубрики: DISCRETE-DIPOLE APPROXIMATION
ENHANCED RAMAN-SCATTERING
METAL FRACTAL CLUSTERS
OPTICAL-PROPERTIES
SELECTIVE PHOTOMODIFICATION
DISORDERED CLUSTERS
NUMERICAL-SIMULATION
SPECTRAL DEPENDENCE
PARTICULATE MATTER
LIGHT-SCATTERING
Ключевые слова (''Своб.индексиров.''): carbon--iron--palladium--silver--article--dipole--electromagnetic field--geometry--mathematical analysis--molecular interaction--nanoparticle--radiation absorption
Аннотация: We calculate the quasistatic electromagnetic density of states for aggregates of touching spheres, in particular, linear chains and computer-generated random fractal aggregates. Multipole moments with orders of up to L=64 are taken into account for random aggregates with the number of particles of up to N=100 and up to L=8000 for linear chains. Extensive comparisons with the dipole approximation and geometrical cluster renormalization method are performed. Extinction spectra are calculated for several metals and black carbon. Long wavelength electromagnetic properties of fractal aggregates are considered in details.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylova S. N., Vtyurin A. N., Bulou A., Krylov A. S., Zamkova N. G.
Заглавие : Lattice dynamics and raman scattering spectrum of elpasolite Rb2KScF6: Comparative analysis
Разночтения заглавия :авие SCOPUS: Lattice dynamics and Raman scattering spectrum of elpasolite Rb 2KScF6: Comparative analysis
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2004. - Vol. 46, Is. 7. - P1311-1319. - ISSN 1063-7834, DOI 10.1134/1.1778457
Примечания : Cited References: 18
Предметные рубрики: STRUCTURAL PHASE-TRANSITION
LIGHT-SCATTERING
OPTICAL PHONONS
SOFT-MODE
CRYSTAL
Аннотация: Raman scattering spectra of elpasolite Rb2KScF6 are studied in a wide temperature range including two phase transitions: from the cubic to the tetragonal phase and then to the monoclinic phase. The experimental Raman scattering spectrum is compared with the lattice vibration spectra of these phases calculated using an ab initio approach. A number of anomalies (caused by structural rearrangement during the phase transitions) are revealed and quantitatively analyzed in the ranges of both the intramolecular vibrations of the octahedron molecular ScF6 ions and low-frequency intermolecular lattice vibrations. The interaction between low-frequency intramolecular vibrations and the intermolecular modes is found to be significant, and strong resonance interaction of the rotational soft modes (which are recovered below the phase transition points) with hard low-frequency vibrations of the rubidium ion sublattice is detected. These interactions are shown to substantially complicate the spectra. (C) 2004 MAIK "Nauka / Interperiodica".
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Karpov S. V., Gerasimov V. S., Isaev I. L., Markel V. A.
Заглавие : Local anisotropy and giant enhancement of local electromagnetic fields in fractal aggregates of metal nanoparticles
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2005. - Vol. 72, Is. 20. - Ст.205425. - ISSN 1098-0121, DOI 10.1103/PhysRevB.72.205425
Примечания : Cited References: 56
Предметные рубрики: SMALL-PARTICLE COMPOSITES
DIFFUSION-LIMITED AGGREGATION
OPTICAL-PROPERTIES
SELECTIVE PHOTOMODIFICATION
NUMERICAL-SIMULATION
DISORDERED CLUSTERS
ABSORPTION-SPECTRUM
PARTICULATE MATTER
NONLINEAR OPTICS
LIGHT-SCATTERING
Аннотация: We have shown within quasistatic approximation that the giant fluctuations of a local electromagnetic field in random fractal aggregates of silver nanospheres are strongly correlated with a local anisotropy factor S which is defined in this paper. The latter is a purely geometrical parameter which characterizes the deviation of local environment of a given nanosphere in an aggregate from spherical symmetry. Therefore, it is possible to predict the sites with anomalously large local fields in an aggregate without explicitly solving the electromagnetic problem. We have also demonstrated that the average (over nanospheres) value of S does not depend noticeably on the fractal dimension D, except when D approaches the trivial limit D=3. In this case, as one can expect, the average local environment becomes spherically symmetrical and S approaches zero. This corresponds to the well-known fact that in trivial aggregates, fluctuations of local electromagnetic fields are much weaker than in fractal aggregates. Thus, we find that, within the quasistatics, the large-scale geometry does not have a significant impact on local electromagnetic responses in nanoaggregates in a wide range of fractal dimensions. However, this prediction is expected not to be correct in aggregates which are sufficiently large for the intermediate- and radiation-zone interaction of individual nanospheres to become important.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Lopatin V. N., Shepelevich N. V., Prostakova I. V.
Заглавие : Modelling optical properties of organic-mineral complexes in water ecosystems
Место публикации : J. Phys. D. - 2005. - Vol. 38, Is. 15. - P.2556-2563. - ISSN 0022-3727, DOI 10.1088/0022-3727/38/15/005
Примечания : Cited References: 22
Предметные рубрики: SCANNING FLOW-CYTOMETRY
LIGHT-SCATTERING
STRATIFIED SPHERE
PARTICLES
INDEX
Ключевые слова (''Своб.индексиров.''): approximation theory--ecosystems--inverse problems--light scattering--mathematical models--refractive index--suspensions (fluids)--water--generalization--integral light scattering indicatrix--organic-mineral complexes--spherical particles--complexation
Аннотация: Characteristics of organic-mineral complexes have been theoretically and experimentally studied in the paper, based on the method of integral light scattering indicatrix. Modelling of optical properties was realized using models of the coated spherical particles with a shell which is constant and changeable in the refractive index profile. General regularities have been revealed and generalized parameters for the method of integral light scattering indicatrix have been suggested.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fausti D., Nugroho A. A., van Loosdrecht PHM, Klimin S. A., Popova M. N., Bezmaternykh L. N.
Заглавие : Raman scattering from phonons and magnons in RFe3(BO3)(4)
Разночтения заглавия :авие SCOPUS: Raman scattering from phonons and magnons in RFe3 (BO3) 4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2006. - Vol. 74, Is. 2. - Ст.24403. - ISSN 1098-0121, DOI 10.1103/PhysRevB.74.024403
Примечания : Cited References: 26
Предметные рубрики: IRON BORATE GDFE3(BO3)(4)
LIGHT-SCATTERING
CRYSTALS
ND
CRYSTALLIZATION
TRANSITIONS
GENERATION
LASER
Аннотация: Inelastic light scattering spectra of several members of the RFe3(BO3)(4) family reveal a cascade of phase transitions as a function of temperature, starting with a structural, weakly first-order, phase transition followed by two magnetic phase transitions. Those consist of the ordering of the Fe-spin sublattice, revealed by all the compounds, and a subsequent spin-reorientational transition for GdFe3(BO3)(4). The Raman data evidence a strong coupling between the lattice and magnetic degrees of freedom in these borates. The Fe-sublattice ordering leads to a strong suppression of the low-energy magnetic scattering, and a multiple peaked two-magnon scattering continuum is observed. Evidence for short-range correlations is found in the "paramagnetic" phase by the observation of a broad magnetic continuum in the Raman data, which persists up to surprisingly high temperatures.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Krylova S. N., Vtyurin A. N., Voronov V. N., Oreshonkov A. S.
Заглавие : Raman Scattering Study Temperature Phase Transitions of Rb2KInF6 Crystal
Место публикации : Ferroelectrics: TAYLOR & FRANCIS LTD, 2011. - Vol. 416. - P95-100. - ISSN 0015-0193, DOI 10.1080/00150193.2011.577713
Примечания : Cited References: 9. - Authors wish to thank prof. K. S. Aleksandrov and prof. I. N. Flerov for their valuable support and useful discussions. This work has been financially supported by grants RFFBR 08-02-00066, 09-02-00062, SS-1011.2008.2.
Предметные рубрики: LIGHT-SCATTERING
LATTICE-DYNAMICS
OPTICAL PHONONS
ELPASOLITE
RB2KSCF6
Ключевые слова (''Своб.индексиров.''): rb2kinf6--temperature phase transitions--raman scattering--lattice dynamics
Аннотация: Raman scattering spectra of Rb2KInF6 crystal have been studied in a wide temperature range, including two phase transitions: from cubic to tetragonal, and then - to the monoclinic phase. Hardening of soft phonon modes was observed that attributes them to the transitions of displacive type. Parameters of Raman lines have been quantitatively analyzed and found in good agreement with known thermodynamic characteristics of these transitions. No evidences of order - disorder processes were observed in the Raman spectra of the high-symmetry phase.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gabrienko A. A., Morozov E. V., Subramani V., Martyanov O. N., Kazarian S. G.
Заглавие : Chemical visualization of asphaltenes aggregation processes studied in situ with ATR-FTIR spectroscopic imaging and NMR imaging
Коллективы : Skolkovo Foundation; BP
Место публикации : J. Phys. Chem. C: American Chemical Society, 2015. - Vol. 119, Is. 5. - P.2646-2660. - ISSN 1932-7447, DOI 10.1021/jp511891f
Примечания : Cited References:78. - This research was performed under the UNIHEAT project. The authors wish to acknowledge the Skolkovo Foundation and BP for financial support. The authors thank BP for providing samples of crude oil
Предметные рубрики: MEXICAN CRUDE OILS
X-RAY-DIFFRACTION
INFRARED-SPECTROSCOPY
PETROLEUM ASPHALTENES
MOLECULAR-DYNAMICS
VARIABLE SELECTION
ORGANIC-SOLVENTS
LIGHT-SCATTERING
N-HEPTANE
NEAR-IR
Аннотация: Crude oil phase behavior and asphaltene precipitation have been studied by two complementary chemical imaging methods for the first time. ATR-FTIR spectroscopic imaging approach has revealed the chemical composition of agglomerated and precipitated asphaltenes upon dilution with a flocculant. Asphaltenes, containing oxygen and nitrogen heteroatomic functional groups, have been detected to be least stable. Aromatic abundant asphaltenes have been observed to have relatively high solubility in crude oil/heptane blends. NMR imaging approach, capable of imaging in the bulk of crude oil samples, has demonstrated that n-heptane causes aggregation which can lead to the stable suspension or to the sedimentation followed by the formation of deposits, depending on flocculant concentration. These processes have been monitored for small and large amounts of heptane added to crude oil. The data obtained by ATR-FTIR spectroscopic imaging and NMR imaging have been correlated to propose a possible link between the chemical structure of asphaltenes and a mechanism of the formation of deposits.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Prosnikov M. A., Smirnov A. N., Davydov, V. Yu, Sablina K. A., Pisarev R. V.
Заглавие : Lattice and magnetic dynamics of a quasi-one-dimensional chain antiferromagnet PbFeBO4
Коллективы : Russian Science Foundation [16-12-10456]
Место публикации : J. Phys.: Condens. Matter: IOP Publishing, 2017. - Vol. 29, Is. 2. - Ст.025808. - ISSN 0953-8984, DOI 10.1088/0953-8984/29/2/025808. - ISSN 1361-648X(eISSN)
Примечания : Cited References:32. - This research was supported by the Russian Science Foundation, grant No. 16-12-10456.
Предметные рубрики: LIGHT-SCATTERING
DIELECTRIC-PROPERTIES
RAMAN-SPECTROSCOPY
Ключевые слова (''Своб.индексиров.''): raman scattering--spin and phonon excitations--spin-phonon interaction--antiferromagnetism--magnetic symmetry analysis--two-magnon scattering
Аннотация: A group of recently synthesized orthorhombic Pnma crystals PbMBO4 (M = Cr, Mn, Fe) demonstrates a number of unusual structural and magnetic properties. We report on polarized Raman scattering study of the lattice and magnetic dynamics in single crystals of an antiferromagnet PbFeBO4 below and above T-N = 114 K. Polarization properties of the observed magnetic excitations below T-N as well as intense quasi-elastic scattering support the quasi-one-dimensional character of the magnetic structure of PbFeBO4. Frequency overlapping of magnetic excitations and low-frequency phonons in the range of 90-200 cm-1 leads to pronounced asymmetric anomalies thus confirming intrinsic coupling of magnetic and lattice subsystems. This conclusion is also supported by observation of anomalous temperature behaviour of higher frequency phonons in the vicinity of T-N. Experimental investigations are supported by relevant magnetic symmetry analysis which allows us to explain previously observed anomalous results.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Parshin A. M.
Заглавие : Optical characteristics of liquid-crystal domains probed by a focused laser beam
Коллективы : Russian Foundation for Basic Research (RFBR) [15-02-06924, 16-53-00073]; Siberian Branch, Russian Academy of Sciences (SB RAS) [2P 0356-2015-0410, 0356-2015-041]
Место публикации : J. Opt. Technol. - 2018. - Vol. 85, Is. 1. - P.22-25. - ISSN 1070-9762, DOI 10.1364/JOT.85.000022. - ISSN 1091-0786(eISSN)
Примечания : Cited References:12. - Russian Foundation for Basic Research (RFBR) (15-02-06924, 16-53-00073); Siberian Branch, Russian Academy of Sciences (SB RAS) (2P 0356-2015-0410, 0356-2015-041).
Предметные рубрики: LIGHT-SCATTERING
POLYMER SURFACE
Аннотация: A technique for determining the optical characteristics of the domain structures of nematic liquid crystals using a focused laser beam is presented. The dependences of the intensity of polarized light on the voltage of a separate nematic domain formed by a polycarbonate surface in the presence of a magnetic field are obtained. It is shown that the optical characteristics cannot be interpreted within the framework of the concept of light scattering, which is suitable in the case of an ensemble of domains probed by a wide laser beam. The analysis of the results is based on the assumption of gradient index optics.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Паршин, Александр Михайлович, Баранник, Алексей Владимирович
Заглавие : Оптическое пропускание доменной структуры нематика на поверхности полимера в магнитном поле
Место публикации : Жидк. кристаллы и их практич. использ. - 2020. - Т. 20, Вып. 2. - С. 62-68. - ISSN 1991-3966, DOI 10.18083/LCAppl.2020.2.62; Liq. Cryst. Appl.
Примечания : Библиогр.: 20
Предметные рубрики: LIGHT-SCATTERING
DEFECTS
Аннотация: Исследовано распространение лазерного луча через слой гибридно-упорядоченного нематика с поверхностной линией дисклинации, состоящий из доменов с радиальной конфигурацией нематического директора на пленке поликарбоната. Ориентационная структура в объеме домена трансформируется в планарную одноосную, задаваемую линией дисклинации, либо в гомеотропную под действием магнитного поля. Получена зависимость интенсивности света, прошедшего через слой, от магнитного поля, прикладываемого перпендикулярно поверхности полимера. Оптическое пропускание сопровождалось интерференционными минимумами и максимумами. Представлена модель интерференции света, основанная на двулучепреломлении, учитывающая рассеяние на ориентационно-структурных неоднородностях доменного ансамбля. Из рассмотрения свободной энергии жидкого кристалла и эффектов двулучепреломления выведено аналитическое выражение, устанавливающее зависимость между интенсивностью света и напряженностью магнитного поля, совпадающее с экспериментом.The propagation of a laser beam through a layer of a hybrid ordered nematic on a polycarbonate film is studied. The nematic has a surface disclination line consisting of domains with a radial configuration of the nematic director. The orientational structure in the domain volume can be transformed into a planar uniaxial structure defined by a disclination line or into a homeotropic one under the influence of a magnetic field. The dependence of the light intensity transmitted through the layer on the magnetic field applied perpendicular to the polymer surface is obtained. Optical transmission was accompanied by interference minima and maxima. Light interference model based on birefringence which takes into account scattering by the orientation-structural inhomogeneities of the domain ensemble is presented. Considering the analysis of the liquid crystal free energy and the birefringence effects, an analytical expression is derived. It establishes the relationship between the light intensity and the magnetic field strength, which coincides with the experiment.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Prosnikov M. A., Bal M. E., Kolkov M. I., Pankrats A. I., Pisarev, R., V, Christianen, P. C. M.
Заглавие : Subterahertz and terahertz spin and lattice dynamics of the insulating ferromagnet PbMnBO4
Коллективы : RFBRRussian Foundation for Basic Research (RFBR); Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science [20-42-240006]; BASIS Foundation [21-1-4-33-1]; HFML-RU/NWO-I, a member of the European Magnetic Field Laboratory (EMFL)
Место публикации : Phys. Rev. Res. - 2022. - Vol. 4, Is. 1. - Ст.013004. - ISSN 2643-1564(eISSN), DOI 10.1103/PhysRevResearch.4.013004
Примечания : Cited References: 62. - M.A.P. greatly acknowledges D. A. Andronikova for aid, B. T. Crow for fruitful discussions, and P. Albers for technicalassistance. Crystal growth was supported by RFBR and the Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science, through Research Project No. 20-42-240006. The theoretical part of the spin dynamics calculations was supported by BASIS Foundation Grant No. 21-1-4-33-1. The support of HFML-RU/NWO-I, a member of the European Magnetic Field Laboratory (EMFL) , is acknowledged
Предметные рубрики: LIGHT-SCATTERING
ANTI-STOKES
BRILLOUIN-SCATTERING
Аннотация: Orthorhombic PbMnBO4 is a rare example of an insulating ferromagnet in which the magnetic properties, in particular the strong magnetic anisotropy, are determined by the Mn3+ Jahn-Teller ion. Here, we report on the detailed investigation of magnetic excitations in the subterahertz and terahertz frequency ranges, as well as lattice excitations in the terahertz range. Using polarized azimuthally resolved Raman spectroscopy, four branches of magnetic excitations were observed and assigned to one acoustic and three optical one-magnon modes. The coupling between ferromagnetic ordering at TC=31K and the Jahn-Teller distortions of [MnO6] octahedra due to the spin-phonon interaction was directly observed for some specific phonon modes involved in these distortions. A spin-wave Hamiltonian was developed that allowed us to determine a unique set of exchange and effective anisotropy parameters. The intensity ratio of the anti-Stokes to Stokes acoustic magnon peaks is found to be anomalous and directly indicates the involvement of the magneto-optical parameters in the magnetic Raman scattering process.
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