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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kostyukov A. S., Gerasimov V. S., Ershov A. E., Bulgakov E. N.
Заглавие : Ring of bound states in the continuum in the reciprocal space of a monolayer of high-contrast dielectric spheres
Коллективы : RFBR Russian Foundation for Basic Research (RFBR); Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science [20-42-240003]; Ministry of Science and Higher Education of the Russian Federation [FSRZ-20200008]
Место публикации : Phys. Rev. B. - 2022. - Vol. 105, Is. 7. - Ст.075404. - ISSN 2469-9950, DOI 10.1103/PhysRevB.105.075404. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 43. - This research was supported by RFBR, Krasnoyarsk Territory, and Krasnoyarsk Regional Fund of Science, Project No. 20-42-240003, by the Ministry of Science and Higher Education of the Russian Federation, Project No. FSRZ-20200008
Предметные рубрики: PHOTONIC BAND-STRUCTURE
FANO RESONANCES
SCATTERING
Аннотация: We consider light scattering by two-dimensional arrays of high-index dielectric spheres arranged into a triangular and square lattices. We demonstrate the appearance of the double degenerate accidental super-BIC modes with extremely suppressed radiative losses in the vicinity of the Γ point of the leaky band of the triangular lattice. Two rings of BICs (circular lines of BICs in reciprocal space) with different polarization appear at the point of the super-BIC destruction. The radius of the ring BIC (RBIC) changes as a function of the sphere's radius. We propose a generic analytical expression to describe the behavior of the guided mode decay rate as a function of the sphere radii and the wave vector in the vicinity of the RBIC. The results are explained using a multipolar approach.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Liu, Ji-Cai, Savchenko, Viktoriia, Kimberg V., Gel'mukhanov F., Odelius, Michael
Заглавие : High-resolution x-ray spectra of carbon monoxide reveal ultrafast dynamics induced by long UV pulse
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [19-29-12015]; National Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [11974108, 11574082]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities [2021MS046]; European UnionEuropean Commission [860553]; Carl Tryggers Foundation [CTS18:285]; Helmholtz Virtual Institute [VI419]; Swedish Research CouncilSwedish Research CouncilEuropean Commission [VR 2019-03470, 2018-05973]
Место публикации : New J. Phys. - 2021. - Vol. 23, Is. 6. - Ст.063030. - ISSN 1367-2630, DOI 10.1088/1367-2630/ac0198
Примечания : Cited References: 47. - The reported study was funded by RFBR, project number 19-29-12015. J-CL thanks the support by the National Science Foundation of China under Grant Nos. 11974108, 11574082, and the Fundamental Research Funds for the Central Universities (No. 2021MS046). MO acknowledges funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skodowska-Curie Grant Agreement No. 860553 and the Carl Tryggers Foundation (contract CTS18:285). FG acknowledges also the support from the Helmholtz Virtual Institute VI419 'Dynamic Pathways in Multidimensional Landscapes'. VK acknowledges the Swedish Research Council (VR 2019-03470). The calculations were partially enabled by resources provided by the Swedish National Infrastructure for Computing (SNIC) partially funded by the Swedish Research Council through Grant Agreement No. 2018-05973
Предметные рубрики: VIBRATIONAL STRUCTURE
SCATTERING
RAMAN
CO
COLLAPSE
PROBE
Аннотация: In theoretical simulations of a UV + x-ray pump-probe (UVX-PP) setup, we show that frequency detuning of the pump UV pulse acts as a camera shutter by regulating the duration of the UVX-PP process. This two-photon absorption with long overlapping UV and x-ray pulses, allowing for high spectral resolution, thereby provides information about ultrafast dynamics of the nuclear wave packet without the requirement of ultrashort pulses and controlled delay times. In a case study of carbon monoxide, the calculated UVX-PP spectra of the O1s−12π1 and C1s−12π1 core-excited states show different vibrational profiles. The interference of intermediate vibrational states reveals details of nuclear dynamics in the UVX-PP process related to a variable duration time controlled by the UV detuning. Both O1s−12π1 and C1s−12π1 pump-probe channels display a splitting of the spectral profile, which however is associated with different physical mechanisms. At the O1s−12π1 resonance, the observed dispersive and non-dispersive spectral bands intersect and result in destructive interference.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Peschanskii A. V., Glamazda, A. Yu., Gudim I. A.
Заглавие : Spectroscopic study of the TbAl3(BO3)4 single crystal: Raman and luminescence spectroscopy
Место публикации : Low Temp. Phys. - 2020. - Vol. 46, Is. 12. - P.1223-1230. - ISSN 1063-777X, DOI 10.1063/10.0002478. - ISSN 1090-6517(eISSN)
Примечания : Cited References: 20
Предметные рубрики: SCATTERING
GENERATION
ND
Аннотация: The vibrational and luminescence properties of the TbAl3(BO3)4 single crystal were studied in the temperature range of 5–300 K. Raman spectra of the single crystal revealed 5 of 7 A1 and all E phonon modes predicted by the group-theory analysis. The splitting energy between the LO and TO components of polar E phonons is determined. A group of intense bands associated with the 5D4 → 7F0 electronic transition was observed in the energy range of 14520–14680 cm−1 of the luminescence spectra. The intensity of these bands decreases upon heating. At the same time, the bands which can be assigned with 5D4 → 7F6, 5D4 → 7F5, and 5D4 → 7F4 transitions were revealed in luminescence spectra at room temperature. The intensity of these bands is comparable to the intensity of the Raman spectrum of TbAl3(BO3)4. The observation of luminescence from the 5D4 multiplet (20600–20750 cm−1) upon excitation at λexc = 632.8 nm (15803 cm−1) and λexc = 532 nm (18797 cm−1) indicates strong nonlinear properties of the studied crystal. The structure of the main 7F6 multiplet of Tb+3 in the TbAl3(BO3)4 single crystal has been studied at 5 K by Raman spectroscopy. The energies of the electronic levels of 7F6 and 5D4 multiplets were determined from the luminescence spectra measured at 300 K.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Peschanskii A. V., Glamazda, A. Yu., Gudim I. A.
Заглавие : Spectroscopic study of the TbAl3(BO3)4 single crystal: Raman and luminescence spectroscopy
Место публикации : Физ. низких температур. - 2020. - Т. 46, Вып. 12. - С.1437-1445. - ISSN 0132-6414. - ISSN 1816-0328(eISSN)
Примечания : Cited References: 20
Предметные рубрики: SCATTERING
GENERATION
ND
Аннотация: The vibrational and luminescence properties of the TbAl3(BO3)4 single crystal were studied in the temperature range of 5–300 K. Raman spectra of the single crystal revealed 5 of 7 A1 and all E phonon modes predicted by the group-theory analysis. The splitting energy between the LO and TO components of polar E phonons is determined. A group of intense bands associated with the 5D4 → 7F0 electronic transition was observed in the energy range of 14520–14680 cm−1 of the luminescence spectra. The intensity of these bands decreases upon heating. At the same time, the bands which can be assigned with 5D4 → 7F6, 5D4 → 7F5, and 5D4 → 7F4 transitions were revealed in luminescence spectra at room temperature. The intensity of these bands is comparable to the intensity of the Raman spectrum of TbAl3(BO3)4. The observation of luminescence from the 5D4 multiplet (20600–20750 cm−1) upon excitation at λexc = 632.8 nm (15803 cm−1) and λexc = 532 nm (18797 cm−1) indicates strong nonlinear properties of the studied crystal. The structure of the main 7F6 multiplet of Tb+3 in the TbAl3(BO3)4 single crystal has been studied at 5 K by Raman spectroscopy. The energies of the electronic levels of 7F6 and 5D4 multiplets were determined from the luminescence spectra measured at 300 K.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Krylova S. N., Kopyl, Svitlana, Krylov A. S., Salehli, Ferid, Zelenovskiy, Pavel, Vtyurin A. N., Kholkin, Andrei
Заглавие : Raman spectra of diphenylalanine microtubes: polarisation and temperature effects
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-02-00754]; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115F227]; project Portugal-Turkey [TUBITAK/0006/2014]; FCT/MEC [UIDB/50011/2020, UIDP/50011/2020]; FCT (Portugal) through the project "BioPiezo" [PTDC/CTM-CTM/31679/2017 (CENTRO-01-0145-FEDER-031679)]; national funds (OE), through FCT-Fundacao para a Ciencia e a Tecnologia, I.P.
Место публикации : Crystals. - 2020. - Vol. 10, Is. 3. - Ст.224. - ISSN 2073-4352, DOI 10.3390/cryst10030224
Примечания : Cited References: 43. - This research was funded by the Russian Foundation for Basic Research grant number 18-02-00754, F.S. thanks Scientific and Technological Research Council of Turkey for support under Grant Number 115F227. S.Kopyl and A.Kholkin thank the joint project Portugal-Turkey TUBITAK/0006/2014. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, refs. UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC. S.Kopyl, P.Z. and A.Kholkin were partly supported by FCT (Portugal) through the project "BioPiezo"-PTDC/CTM-CTM/31679/2017 (CENTRO-01-0145-FEDER-031679). Part of this work was funded by national funds (OE), through FCT-Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of 29 August, changed by Law 57/2017, of 19 July.
Предметные рубрики: PIEZOELECTRIC PROPERTIES
PHASE-TRANSITIONS
SPECTROSCOPY
SCATTERING
Аннотация: Diphenylalanine microtubes have remarkable physical properties that allow one to use them in electronics. In this work, we measured polarised temperature-dependent Raman spectra in self-assembled diphenylalanine microtubes grown from the solution. We observed the anomalous temperature behaviour of the Raman lines. Their temperature changes were minimal, which required a significant improvement in the resolution and stability of Raman measurements. The anomalies in the behaviour of the spectra at about 178 K, 235 K, 255 K, 278 K, 296 K, 398 K and 412 K were observed. The structural phase transition at 398 K is irreversible. This transition is associated with the release of water molecules from nanochannels. The irreversible phase transition has a temperature range of about 10 K.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Parshin A. M., Barannik A. V., Zyryanov V. Ya., Shabanov V. F.
Заглавие : Light interference in a hybrid-aligned nematic layer with nonordered surface disclination lines
Место публикации : J. Opt. Soc. Am. B. - 2020. - Vol. 37, Is. 7. - P.2053-2057. - ISSN 0740-3224, DOI 10.1364/JOSAB.395976. - ISSN 1520-8540(eISSN)
Примечания : Cited References: 19
Предметные рубрики: LIQUID-CRYSTAL
SCATTERING
DEFECTS
DOMAINS
Аннотация: The propagation of a laser beam through a hybrid-aligned nematic layer with a surface disclination line has been investigated. A model of the light interference has been developed to consider the scattering by the structural inhomogeneities. The analytical expression that includes the factor characterizing an exponential decrease in the light scattering has been obtained. The dependence of the intensity of light transmitted through the layer on the magnetic field has been measured. The dependence has been accompanied by the interference oscillations. The theoretical expression is consistent with the experiment, which confirms the correctness of the model concepts.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Vtyurin A. N., Voronov V. N., Krylova S. N.
Заглавие : Manifestations of Structural Phase Transitions in a Rb2KLuF6 Crystal in Its Raman Spectra
Коллективы : Russian Foundation for Basic Research [16-02-00102, 18-02-00754]
Место публикации : Opt. Spectrosc. - 2019. - Vol. 126, Is. 4. - P.341-345. - ISSN 0030-400X, DOI 10.1134/S0030400X1904012X. - ISSN 1562-6911(eISSN)
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research, project nos. 16-02-00102, 18-02-00754.
Предметные рубрики: SCATTERING
ELPASOLITES
LUMINESCENCE
TRANSFORMATIONS
FLUORIDES
Аннотация: The Raman spectra of an Rb2KLuF6 crystal are studied in the temperature range from 8 to 375 K, which includes two phase transitions: one of which proceeds from a cubic to a tetragonal phase, while the other transition takes place from a tetragonal to a monoclinic phase. An analysis of the temperature dependences of parameters of spectral lines shows that the former transition is of the second kind, while the latter transition is of the first kind, close to the tricritical point. It is shown that the structural phase transitions in the Rb2KLuF6 double perovskite are not associated with disordering. The former transition is associated with rotations of LuF6 octahedra around the fourth-order axis, while the latter transition is related with rotations of octahedra and displacements of rubidium ions.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Izotov A. V., Belyaev B. A., Solovev P. N., Boev N. M.
Заглавие : Two-Magnon Relaxation Processes in Nanocrystalline Thin Magnetic Films
Коллективы : Russian Ministry of Education and Science [3.1031.2017/PCh]
Место публикации : Russ. Phys. J. - 2019. - Vol. 61, Is. 12. - P.2313-2320. - ISSN 1064-8887, DOI 10.1007/s11182-019-01673-4. - ISSN 1573-9228(eISSN)
Примечания : Cited References: 25. - This research was done with support of the Russian Ministry of Education and Science, task No. 3.1031.2017/PCh.
Предметные рубрики: FERROMAGNETIC-RESONANCE LINEWIDTH
MICROMAGNETIC CALCULATION
SCATTERING
Аннотация: Numerical analysis of the micromagnetic model was used to reveal the ‘resonance’ feature of relaxation processes in nanocrystalline thin magnetic films. This feature manifests itself in the form of sharp broadening of the ferromagnetic resonance (FMR) line at a certain frequency f1 depending on magnetic characteristics of the film, and is observed only in films the thickness of which exceeds some threshold value dmin. Sharp broadening of the FMR line is accompanied by significant shift of the resonance field, whereas the shift value changes the sign at frequency ~ f1. It was shown analytically that the nature of observed effects is associated with the two-magnon process of spin waves scattering on quasi-periodic magnetic microstructure – magnetization ‘ripple’. Obtained expressions for the threshold value of film thickness dmin and frequency of maximum broadening of FMR line f1 agree well with the results of numerical computation of micromagnetic model.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Loiko V. A., Zyryanov V. Ya., Konkolovich A. V., Miskevich A. A.
Заглавие : Light transmission of polymer-dispersed liquid crystal layer composed of droplets with inhomogeneous surface anchoring
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 120, Is. 1. - P.143-152. - ISSN 0030-400X, DOI 10.1134/S0030400X16010112. - ISSN 1562-6911(eISSN)
Примечания : Cited References:43. - This work was supported by the National Academy of Sciences of Belarus and the Siberian Branch of the Russian Academy of Sciences (project no. 36) and the Belarusian Republican Foundation for Fundamental Research (project no. F15SO-039).
Предметные рубрики: NEMATIC DROPLETS
IONIC MODIFICATION
FIELD
TRANSITIONS
SCATTERING
PARTICLES
INTERFACE
DISPLAYS
Аннотация: We have developed a model and realized an algorithm for the calculation of the coefficient of coherent (direct) transmission of light through a layer of liquid crystal (LC) droplets in a polymer matrix. The model is based on the Hulst anomalous diffraction approximation for describing the scattering by an individual particle and the Foldy-Twersky approximation for a coherent field. It allows one to investigate polymer dispersed LC (PDLC) materials with homogeneous and inhomogeneous interphase surface anchoring on the droplet surface. In order to calculate the configuration of the field of the local director in the droplet, the relaxation method of solving the problem of minimization of the free energy volume density has been used. We have verified the model by comparison with experiment under the inverse regime of the ionic modification of the LC-polymer interphase boundary. The model makes it possible to solve problems of optimization of the optical response of PDLC films in relation to their thickness and optical characteristics of the polymer matrix, sizes, polydispersity, concentration, and anisometry parameters of droplets. Based on this model, we have proposed a technique for estimating the size of LC droplets from the data on the dependence of the transmission coefficient on the applied voltage.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ignatchenko V. A., Tsikalov D. S.
Заглавие : Green's functions of the scalar model of electromagnetic fields in sinusoidal superlattices
Место публикации : Physica B: Elsevier, 2016. - Vol. 485. - P.94-102. - ISSN 09214526 (ISSN), DOI 10.1016/j.physb.2016.01.006
Примечания : Cited References: 30
Предметные рубрики: SCATTERING
MEDIA
PROPAGATION
GRATINGS
DENSITY
LIGHT
Ключевые слова (''Своб.индексиров.''): green's functions--electromagnetic waves--scalar model--sinusoidal superlattices--photonic crystals--ldos
Аннотация: Problems of obtaining Green's function and using it for studying the structure of scalar electromagnetic fields in a sinusoidal superlattice are considered. An analytical solution of equation in the k-space for Green's function is found. Green's function in the r-space is obtained by both the numerical and the approximate analytical Fourier transformation of that solution. It is shown, that from the experimental study of Green's function in the k-space the position of the plane radiation source relative to the extremes of the dielectric permittivity ?(z) can be determined. The relief map of Green's function in the r-space shows that the structure of the field takes the form of chains of islets in the plane ?z, the number of which increases with increasing the distance from a radiation source. This effect leads to different frequency dependences of Green's function at different distances from the radiation source and can be used to measure the distance to the internal source. The real component of Green's function and its spatial decay in the forbidden zones in the near field is investigated. The local density of states, depending on the position of the source in the superlattice, is calculated.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sobol A. A., Shukshin V. E., Zaitsev A. I.
Заглавие : Raman spectroscopy of SrB4O7 single crystals in the temperature range 300–1273 K
Место публикации : Opt. Spectrosc.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 121, Is. 1. - P.25-31. - ISSN 0030400X (ISSN), DOI 10.1134/S0030400X16070201
Примечания : Cited References: 20. - This work was supported by the Russian Foundation for Basic Research, project no. 13-02-00707a.
Предметные рубрики: STRONTIUM TETRABORATE
PHASE-TRANSITIONS
SCATTERING
SPECTRA
Аннотация: The polarized Raman spectra of SrB4O7 (SBO) single crystals are studied in detail in the temperature range of 300–1273 K. The TO, LO, and IO phonon lines of A1, A2, B1, and B2 symmetries of rhombic SBO at 300 K are identified. The behavior of the Raman spectra of SBO crystals is studied upon heating up to their melting. The relation of Raman spectra with the structure of boron–oxygen fragments, as well as the transformation of spectra in the process of melting of SBO crystals, is discussed. © 2016, Pleiades Publishing, Ltd.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Morozov E. V., Martyanov O. N.
Заглавие : Probing flocculant-induced asphaltene precipitation via NMR imaging: from model toluene-asphaltene systems to natural crude oils
Коллективы : Russian Science Foundation [15-19-00119]
Место публикации : Appl. Magn. Reson.: Springer, 2016. - Vol. 47, Is. 2. - P.223-235. - ISSN 0937-9347, DOI 10.1007/s00723-015-0741-9. - ISSN 1613-7507(eISSN)
Примечания : Cited References:46. - This research was performed with the financial support of Russian Science Foundation (project no. 15-19-00119).
Предметные рубрики: PETROLEUM ASPHALTENES
MOLECULAR-DYNAMICS
AGGREGATION
MICROSCOPY
SCATTERING
RESONANCE
SEDIMENTATION
ASSOCIATION
CALORIMETRY
RELAXATION
Аннотация: An nuclear magnetic resonance (NMR) imaging approach for studying flocculant-induced asphaltene precipitation processes is introduced in this report. Unlike commonly accepted techniques, which primarily measure aggregation processes on the submicron scale (the level of asphaltene molecules and their aggregates), NMR imaging demonstrates the capability to obtain new useful information about bulk system behavior on the macro scale. To reveal the capabilities of the method, the model toluene-asphaltene system and two samples of natural crude oils with different chemical composition and physical properties (such as asphaltene content and density) were employed for experiments. The process of colloidal suspension formation and two different patterns of its evolution were observed depending on both the asphaltene content and the flocculant concentration. In the first pattern, the flocculant-induced precipitation leads to the slow uniform compacting of the suspension and descent of the sedimentation front, whereas the second pattern is characterized by sediment accumulation and the upwards drift of the front. It was found that the behavior of the precipitated asphaltenes in the model system correlates well with those observed in natural crude oils. The results achieved in this work are in agreement with the data obtained previously via other techniques. Thus, NMR imaging proved to be an efficient method for probing flocculant-induced precipitation in crude oils.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Handunkanda S. U., Curry E. B., Voronov V. N., Said, Ayman H., Guzman-Verri G. G., Brierley R. T., Littlewood P. B., Hancock J. N.
Заглавие : Large isotropic negative thermal expansion above a structural quantum phase transition
Место публикации : Phys. Rev. B: American Physical Society, 2015. - Vol. 92, Is. 13. - Ст.134101. - ISSN 1098, DOI 10.1103/PhysRevB.92.134101. - ISSN 1550235X(eISSN)
Примечания : Cited References:35. - The authors also acknowledge the valuable conversations with Joe Budnick and Gabe Aeppli. Work at the University of Connecticut is supported by National Science Foundation Award No. DMR-1506825. Work at the University of Costa Rica is supported by Vicerrectoria de Investigacion under Project No. 816-B5-220, and work at Argonne National Laboratory is supported by the US Department of Energy, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357. R.T.B. acknowledges support from the Yale Prize Postdoctoral Fellowship. The construction of HERIX was partially supported by the NSF under Grant No. DMR-0115852.
Предметные рубрики: SCF3 CRYSTAL
CUBIC SCF3
DYNAMICS
SCATTERING
SRTIO3
Аннотация: Perovskite structured materials contain myriad tunable ordered phases of electronic and magnetic origin with proven technological importance and strong promise for a variety of energy solutions. An always-contributing influence beneath these cooperative and competing interactions is the lattice, whose physics may be obscured in complex perovskites by the many coupled degrees of freedom, which makes these systems interesting. Here, we report signatures of an approach to a quantum phase transition very near the ground state of the nonmagnetic, ionic insulating, simple cubic perovskite material ScF3, and show that its physical properties are strongly effected as much as 100 K above the putative transition. Spatial and temporal correlations in the high-symmetry cubic phase determined using energy- and momentum-resolved inelastic x-ray scattering as well as x-ray diffraction reveal that soft mode, central peak, and thermal expansion phenomena are all strongly influenced by the transition.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Oreshonkov A. S., Khodzhibaev A. K., Krylov A. S., Umarov M. F., Vtyurin A. N.
Заглавие : Raman spectroscopy study of the behavior of the soft mode in a structural phase transition in the Pr3Sb5O12 crystal
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 57, Is. 11. - P.2286-2289. - ISSN 1063-7834, DOI 10.1134/S1063783415110256
Примечания : Cited References: 15. - The study was supported in part by the Ministry for Education and Science of the Russian FederationErrutum: The fourth affiliation and e-mail of the corresponding author should read as follows: Vologda State University, ul. Lenina 15, Vologda, 160000 Russia *e-mail: oreshonkov@iph.krasn.ru
Предметные рубрики: SCATTERING
Аннотация: The structural phase transition in the Pr3Sb5O12 crystal has been studied using Raman spectroscopy. The phase transition is accompanied by the recovery of the soft mode below T = 735 K, which is associated with the displacements of the oxygen and antimony atoms. © 2015, Pleiades Publishing, Ltd.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Rasskazov I. L., Karpov S. V., Markel V. A.
Заглавие : Waveguiding properties of short linear chains of nonspherical metal nanoparticles
Коллективы : U.S. National Science Foundation [DMS1216970]; Russian Academy of Sciences [24.29, 24.31, III.9.5, 43]; SFU [101]; Russian Ministry of Education and Science [1792]
Место публикации : J. Opt. Soc. Am. B: Optical Society of America, 2014. - Vol. 31, Is. 12. - P.2981-2989. - ISSN 0740-3224, DOI 10.1364/JOSAB.31.002981. - ISSN 1520-8540
Примечания : Cited References: 39. - This research was supported in part by the U.S. National Science Foundation under Grant DMS1216970; by the Russian Academy of Sciences under Grants 24.29, 24.31, III.9.5, 43, and SFU (101); and by the Russian Ministry of Education and Science under Contract 1792.
Предметные рубрики: DISPERSION-RELATIONS
MODES
SCATTERING
ARRAYS
GUIDES
LIGHT
GAIN
Аннотация: We study numerically the discrete dispersion relations and waveguiding properties of relatively short linear chains of spherical and spheroidal silver nanoparticles. Simulations are based on the Drude model for the dielectric permittivity of metal and on the dipole approximation for the electromagnetic interaction of particles. We also simulate the dynamics of femtosecond optical pulse propagation along such chains. In the case that we consider (10 particles per chain), reflections from the chain terminals play a significant detrimental role. We show that dissipative traps can be used to reduce the effects of reflections. We also show that chains composed of oblate spheroids with sufficiently small aspect ratio (nanodisks) have better waveguiding properties when compared to chains made of particles with other spheroidal shapes. This includes a slower rate of decay, larger group velocity, and larger bandwidth.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F., Gerasimov V. P., Zyryanov V. Ya.
Заглавие : Resonant angular conversion in a Fabry-Perot resonator holding a dielectric cylinder
Коллективы : RFBR [13-02-00497, 43, 101, 24.29]
Место публикации : J. Opt. Soc. Am. A: Optical Society of America, 2014. - Vol. 31, Is. 2. - P.264-267. - ISSN 1084-7529, DOI 10.1364/JOSAA.31.000264. - ISSN 1520-8532
Примечания : Cited References: 8. - This work was partially supported by RFBR grant 13-02-00497, and grants no. 43, 101 and 24.29 of SB RAS, and NSCT-SB RAS. We thank D. N. Maksimov for critical reading of the manuscript.
Предметные рубрики: SCATTERING
SURFACE
Аннотация: Light transmission through a Fabry–Perot resonator (FPR) holding a dielectric cylinder rod is considered. For the cylinder parallel to mirrors of the FPR and the mirrors mimicked by the δ functions we present an exact analytical theory. It is shown that light transmits only for resonant incident angles, αm, similar to the empty FPR. However after transmission the light scatters into different resonant angles, αm′ , performing resonant angular conversion. We compare the theory with experiment in the FPR, exploring multilayer films as the mirrors and glass cylinder with diameter coincided with the distance between the FPR mirrors. The measured values of angular light conversion agree qualitatively with the theoretical results.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev E. N.
Заглавие : Bloch bound states in the radiation continuum in a periodic array of dielectric rods
Коллективы : Russian Science Foundation [14-12-00266]
Место публикации : Phys. Rev. A: American Physical Society, 2014. - Vol. 90, Is. 5. - Ст.53801. - ISSN 1050-2947, DOI 10.1103/PhysRevA.90.053801. - ISSN 1094-1622
Примечания : Cited References: 35. - The work was supported by the Russian Science Foundation through Grant No. 14-12-00266. We acknowledge discussions with D. N. Maksimov.
Предметные рубрики: WAVE-GUIDE
SCATTERING
CYLINDERS
CHANNEL
Аннотация: We consider an infinite periodic array of dielectric rods in vacuum with the aim to demonstrate three types of Bloch bound states in the continuum (BSCs): symmetry protected with a zero Bloch vector, embedded in one diffraction channel with nonzero Bloch vector, and embedded in two and three diffraction channels. The first and second types of the BSC exist for a wide range of material parameters of the rods, while the third occurs only at a specific value of the radius of the rods. We show that the second type supports the power flux along the array. In order to find BSCs we put forward an approach based on the expansion over the Hankel functions. We show how the BSC reveals itself in the scattering function when the singular BSC point is approached along a specific path in the parametric space.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F.
Заглавие : Feshbach projection formalism for transmission through a time-periodic potential
Место публикации : Phys. Rev. E: American Physical Society, 2012. - Vol. 86, Is. 5. - Ст.56211. - ISSN 1539-3755, DOI 10.1103/PhysRevE.86.056211
Примечания : Cited References: 33
Предметные рубрики: NUCLEAR REACTIONS
UNIFIED THEORY
QUANTUM
FIELD
SCATTERING
SYSTEM
STATES
Аннотация: The Feshbach projection formalism is applied to consider quantum transmission through a tight-binding wire subject to a time-periodic potential. The wire is coupled with two leads via the coupling constant v(C). The periodicity of the potential implies an additional temporal dimension that reduces the problem to stationary transmission through an effectively two-dimensional lattice system. The non-Hermitian effective Hamiltonian is formulated. Thist allows us to trace the redistribution of resonance positions and resonance widths with the growth of v(C) from the weak-coupling to the strong-coupling regime.
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19.

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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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krylov A. S., Merkushova E. M., Vtyurin A. N., Isaenko L. I.
Заглавие : Raman spectroscopic study of the lattice dynamics in the Rb2KMoO3F3 oxyfluoride
Место публикации : Phys. Solid State: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 54, Is. 6. - P.1275-1280. - ISSN 1063-7834, DOI 10.1134/S1063783412060170
Примечания : Cited References: 24. - This study was supported by the Russian Foundation for Basic Research (project nos. 11-02-98002-r_sibir', 09-02-00062, and NSh-4645.2010.2).
Предметные рубрики: PHASE-TRANSITIONS
SCATTERING
(NH4)3WO3F3
CRYSTALS
DISORDER
Cs
Аннотация: The lattice dynamics of the Rb2KMoO3F3 oxyfluoride has been studied by Raman spectroscopy in the temperature range 7–400 K. A phase transition has been revealed at T ≈ 185 K with decreasing temperature. Anomalies of the frequencies and Raman line half-widths have been analyzed. No condensation of soft lattice modes has been found. The character of changes in the Raman spectra of the Rb2KMoO3F3 oxyfluoride shows that the phase transition is related to variations in the [MoO3F3]3− molecular octahedron.
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