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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Nemtsev I. V., Shabanova O. V., Tambasov I. A., Ivanenko A. A., Cherepakhin A. V., Shestakov N. P., Zyryanov V. Ya.
Заглавие : Methods to determine crystal lattice parameters of opal-like structures
Место публикации : J. Struct. Chem. - 2021. - Vol. 62, Is. 4. - P.641-650. - ISSN 00224766 (ISSN), DOI 10.1134/S0022476621040168
Примечания : Cited References: 45. - The research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme No. AAAA-A18-118041990041-8)
Аннотация: Series of high-quality spherical poly(methyl methacrylate) particles with a polydispersity less than 5% are prepared by chain-growth emulsifier-free controlled radical emulsion polymerization of methyl methacrylate in water. The average diameters in the series varied from 237 nm to 447 nm. The physico-chemical properties of obtained submicrospheres can be varied to make them more stable and stronger by a modified classical synthesis technology whereby 4-10 vol.% of dispersion medium is replaced by acetone. 2D and 3D photonic crystal structures, opals, are prepared from poly(methyl methacrylate) submicrospheres. The crystal structure of the opals is studied by IR spectroscopy and scanning electron microscopy. According to the spectroscopic data, the poly(methyl methacrylate) particles contain significant amounts of water whose evaporation leads to the shrinkage of the spheres. The stereoregularity of the synthesized polymer is studied, the glass-transition temperatures of obtained samples are determined.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zobov V. E., Lundin A. A.
Заглавие : Effect of degradation processes caused by a small perturbation on the growth of the average cluster size of correlated spins in multiple quantum NMR spectroscopy of solids
Место публикации : Appl. Magn. Reson. - 2021. - Vol. 52. Is. 7. - P.879–892. - ISSN 09379347 (ISSN), DOI 10.1007/s00723-021-01342-1
Примечания : Cited References: 33. - The study is funded by the Ministry of Science and Higher Education of the Russian Federation in the framework of the State assignment, State registration number AAAA-A19-119012890064-7
Аннотация: Multiple quantum (MQ) NMR spectroscopy of solids allows one to observe the growth and decay of multispin correlations. As a rule, the average size of the cluster of correlated spins is extracted from the width of the MQ spectrum. In the present article, the size distribution of such clusters is explored. To obtain the above distribution, the solutions for the amplitudes of the decomposition over complete sets of orthogonal operators for the two different models were used. By means of these models, we have taken into account the dependence of cluster degradation (the degradation of a cluster means, e.g., destruction of correlations in cluster or loss of particles in it) through two positions. The first one defines by the cluster size while the second one depends on the MQ coherence order of the cluster. It is shown that in dependence of the relation the rates of these degradation processes, the width of the MQ spectrum carries different information. If the first process is faster that the second one, then the width of the MQ spectrum is still determined by the average cluster size. When the velocity ratio becomes inverse, the width of the MQ spectrum takes on a smaller value, which is a consequence of the faster degradation of the MQ spectrum components with large orders of coherence.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vorob’ev S. A., Burdakova E. A., Sarycheva A. A., Volochaev M. N., Karacharov A. A., Likhatskii M. N., Mikhlin Y. L.
Заглавие : Analysis of function of copper sulfide nanoparticles as sphalerite flotation activator
Место публикации : J. Min. Sci. - 2021. - Vol. 57, Is. 1. - P.144-153. - ISSN 10627391 (ISSN), DOI 10.1134/S1062739121010154
Примечания : Cited References: 22. - This study was supported by the Russian Science Foundation, project no. 18-17-00135
Аннотация: The authors compare the effect exerted by copper ions and sulphide copper nanoparticles on flotation of Gorevka deposit sphalerite using potassium n-butyl xanthate and in reagent-less regime. Covelline-like colloid particles 4–8 nm in size, obtained in interaction of copper (II) and sulfide ions in aqueous solutions, are characterized using the methods of dynamic light scattering, electron microscopy and diffraction. Sphalerite surface after reaction with copper ions and CuS dispersoid solutions are described by zeta-potential measurements and X-ray photoelectron spectroscopy. It is found that sphalerite flotation after activation with nanoparticles is lower than with copper ion solutions of the same concentrations, and improves with increasing duration of activation and flotation processes. The mechanism of CuS nanoparticles consists in creation of active centers for the collector to attach to, which intensifies the hydrophobic behavior and adsorption of the collector. Moreover, CuS nanoparticles promote formation of a special microrelief of the solid–liquid interface, which ensures rupture of liquid film and attachment of sphalerite particles to air bubbles when they collide.
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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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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gerasimova Yu. V., Laptash N. M., Krylov A. S., Vonog V., Vtyurin A. N.
Заглавие : Structural phase transition in (NH4)3GeF7– Raman spectroscopy data
Место публикации : Crystals. - 2021. - Vol. 11, Is. 5. - Ст.506. - ISSN 20734352 (ISSN), DOI 10.3390/cryst11050506
Примечания : Cited References: 22. - This research was partially funded by RFBR and DFG, project No. 21-52-12018
Аннотация: We obtained Raman spectra of (NH4)3GeF7 crystals with a wide range of frequencies (10–3400 cm−1) and temperatures (8–300 K), including phase transition, which was accompanied by a symmetry increase with a temperature decrease. The internal vibrations of the GeF62− group were classified by the positional symmetry method. Considerable transformations of the Raman spectra were observed at the lower frequency range of lattice vibrations and the ranges of the internal vibrations of the ammonium ions. In contrast, the internal modes of the GeF62− groups changed only slightly due to their resonance splitting in the multiplied unit cell, which agreed well with the proposed phase transition mechanism induced by ammonium group ordering.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Saikova S., Pavlikov A., Trofimova T., Mikhlin Y., Karpov D., Asanova A., Grigoriev Y., Volochaev M. N., Samoilo A., Zharkov S. M., Velikanov D. A.
Заглавие : Hybrid nanoparticles based on cobalt ferrite and gold: Preparation and characterization
Место публикации : Metals. - 2021. - Vol. 11, Is. 5. - Ст.705. - ISSN 20754701 (ISSN), DOI 10.3390/met11050705
Примечания : Cited References: 74
Аннотация: During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 20 nm, decorated with 2 nm gold clusters, were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The methionine was used to grow the Au clusters to a solid gold shell (up to 10 gold deposition cycles). The obtained nanoparticles (NPs) were studied by X-Ray diffraction (XRD), transmis-sion electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-Ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy techniques. The TEM images of the obtained HNPs showed that the surface of cobalt ferrite was covered with gold nanoclusters, the size of which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after 1 cycle to 2.46 ± 0.13 nm after 10 cycles). The density of the Au clusters on the cobalt ferrite surface insignificantly decreased during repeated stages of gold deposition: 21.4 ± 2.7 Au NPs/CoFe2O4 NP after 1 cycle, 19.0 ± 1.2 after 6 cycles and 18.0 ± 1.4 after 10 cycles. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behavior, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesized HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shakirova A. A., Tomilin F. N., Pomogaev V. A., Vnukova N. G., Churilov G. N., Kudryasheva N. S., Tchaikovskaya O. N., Ovchinnikov S. G., Avramov P. V.
Заглавие : Synthesis, mass spectroscopy detection, and density functional theory investigations of the Gd endohedral complexes of C82 fullerenols
Коллективы : RFBRRussian Foundation for Basic Research (RFBR) [18-29-19003 MK]; Russian Ministry of Science and EducationMinistry of Education and Science, Russian Federation [0721-2020-0033]; Collaborative NRF-RFBR grant (Korean) [NRF-2019K2A9A1A06100125]; Collaborative NRF-RFBR grant (Russian) [19-53-51005 NIFa RFFI-Korea]; NRF [2021R1A2C1010455]
Место публикации : Computation. - 2021. - Vol. 9, Is. 5. - Ст.58. - ISSN 2079-3197(eISSN), DOI 10.3390/computation9050058
Примечания : Cited References: 41. - The experimental results were funded by RFBR project No. 18-29-19003 MK. The quantum chemical study was funded by project 0721-2020-0033 of the Russian Ministry of Science and Education. The collaboration and coordination of Russian and Korean teams was supported by Collaborative NRF-RFBR grant (Korean ID: NRF-2019K2A9A1A06100125; Russian ID: Project No. 19-53-51005 NIFa RFFI-Korea) and NRF 2021R1A2C1010455 grant
Предметные рубрики: ZETA VALENCE QUALITY
BIOLOGICAL-ACTIVITY
BASIS-SETS
TOXICITY
Аннотация: Gd endohedral complexes of C82 fullerenols were synthesized and mass spectrometry analysis of their composition was carried out. It was established that the synthesis yields a series of fullerenols Gd@C82Ox(OH)y (x = 0, 3; y = 8, 16, 24, 36, 44). The atomic and electronic structure and properties of the synthesized fullerenols were investigated using the density functional theory calculations. It was shown that the presence of endohedral gadolinium increases the reactivity of fullerenols. It is proposed that the high-spin endohedral fullerenols are promising candidates for application in magnetic resonance imaging.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grishina, Svetlana, Goryainov, Sergey, Oreshonkov A. S., Karmanov, Nikolay
Заглавие : Micro-Raman study of cesanite (Ca2Na3(OH)(SO4)3) in chloride segregations from Udachnaya-East kimberlites
Коллективы : International GeoRaman Conference
Место публикации : J. Raman Spectrosc. - 2022. - Vol. 53, Is. 3: Special Issue: GEORAMAN 2020. - P.497-507. - ISSN 0377-0486, DOI 10.1002/jrs.6168. - ISSN 1097-4555(eISSN)
Примечания : Cited References: 33
Предметные рубрики: CARBONATE
IDENTIFICATION
INSIGHTS
APATITE
Аннотация: Cesanite (Ca2Na3(OH)(SO4)3), a rare mineral, has been found in a few places restricted to a geothermal field and caves. We report the new occurrence of cesanite in quite different geological site—within sulfate-rich melt inclusions in chloride segregations from kimberlites of Udachnaya-East pipe (Siberia). Two halite generations: сesanite free and сesanite-bearing, were distinguished in concentrically zonal segregations according to the results of the mineral and sulfate melt inclusion study by micro-Raman spectroscopy and SEM-EDS. We have applied the Raman spectroscopy and first principles calculations to understand structural and vibrational properties of cesanite daughter mineral in polyphase sulfate inclusions. Polarized spectra provided additional information on the overlapped components of the spectral profile. The Raman spectra of cesanite in the range of OH stretching vibrations are reported for the first time. The study aims to clarify the source of the NaSCl-enrichment in the Udachnaya-East pipe, which is highly discussed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yushina I., Krylov A. S., Leonidov I. I., Batalov V., Chen Y. S., Wang S. G., Stash A., Bartashevich E. V.
Заглавие : The influence of chalcogen atom on conformation and phase transition in chalcogenazinoquinolinium monoiodides
Коллективы : Ministry of Science and High Education of Russian Federation [FENU 2020-0019]; ISSC UB RAS [AAAA-A19-119031890025-9]; Divisions of Chemistry (CHE) and Materials Research (DMR), National Science Foundation [NSF/CHE-1346572]; US DOEUnited States Department of Energy (DOE) [DE-AC02-06CH11357]
Место публикации : Acta Crystallogr. B. - 2021. - Vol. 77. - P.526-536. - ISSN 2052-5206, DOI 10.1107/S2052520621004571
Примечания : Cited References: 61. - This work was supported by the Ministry of Science and High Education of Russian Federation, project FENU 2020-0019. Additional spectroscopic studies were carried out in ISSC UB RAS (Research Program No. AAAA-A19-119031890025-9). Technical assistance from Ivan D. Popov (ISSC UB RAS) is strongly acknowledged. ChemMatCARS Sector 15 is principally supported by the Divisions of Chemistry (CHE) and Materials Research (DMR), National Science Foundation, under grant number NSF/CHE-1346572. Use of the Advanced Photon Source, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the US DOE under Contract No. DE-AC02-06CH11357
Предметные рубрики: LARGE STOKES SHIFT
D-PI-A
HALOGEN BONDS
ELECTRON LOCALIZATION
Аннотация: Crystalline chalcogenazinoquinolinium monoiodides, where the chalcogen atom is oxygen and sulfur, were studied using a combination of X-ray diffraction, Raman and UV-vis spectroscopies and photoluminescence experimental techniques. Periodic quantum-chemical calculations were performed to characterize the features of electronic structure and vibrational assignment. X-ray diffraction and Raman spectroscopy experiments consistently reveal phase transition of thiazinoquinolinium monoiodide at low temperatures with the decrease of symmetry to P1. The luminescence study for oxazinoquinolinium monoiodide reveals the excitation maximum at 532 nm and emission at 650 nm with significantly higher intensity than for the thiazinoquinolinium derivative. The studied chalcogenazinoquinolinium monoiodides demonstrate high values of Stokes shift up to 150 nm.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Falaleev O. V., Kukhlevsky O. P., Keeperman E. M.
Заглавие : Fine srtucture of PMR line shape in Ca(OH)2 single crystal
Коллективы : Soviet-indian symposium on actual problems of magnetic resonance spectroscopy of inorganic materials, Академия наук СССР, Indian national academy of sciences, Академия наук Таджикской ССР
Место публикации : Proceedings of the 1st soviet-indian symposium on actual problems of magnetic resonance spectroscopy of inorganic materials. - Dushanbe, 1982. - P.72-73
Примечания : Библиогр.: 4
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11.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Buznik V. M., Vopilov V. A., Livshits A. I.
Заглавие : Nuclear magnetic resonance study of solid electrolytes
Коллективы : Soviet-indian symposium on actual problems of magnetic resonance spectroscopy of inorganic materials, Академия наук СССР, Indian national academy of sciences, Академия наук Таджикской ССР
Место публикации : Proceedings of the 1st soviet-indian symposium on actual problems of magnetic resonance spectroscopy of inorganic materials. - Dushanbe, 1982. - P.66-67
Примечания : Библиогр.: 0
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Udod L. V., Romanova O. B., Aplesnin S. S., Kretinin V. V.
Заглавие : Study of structural properties of bismuth pyrostannate by Raman and IR spectroscopy
Место публикации : Sib. J. Sci. Technol. - 2020. - Vol. 21, Is. 4. - P.556-564. - ISSN 2587-6066, DOI 10.31772/2587-6066-2020-21-4-556-564; \b Сибирский журнал науки и технологий
Примечания : Cited References: 19. - The reported study was funded by RFBR according to the research project № 20-52-00005 Bel_a
Аннотация: Chromium-substituted bismuth pyrostannates with a pyrochlore structure were synthesized by the solid-phase reaction method. The X-ray structural analysis performed at room temperature showed that the samples Bi2(Sn1-xCrx)2O7, x = 0; 0.05, 0.1 are single-phase and belong to the Pc monoclinic structure. Polymorphic transformations of the synthesized samples were studied by Raman and IR spectroscopy. IR spectra were obtained at the temperature range 110–525 K and frequencies 350–1100 cm–1. Raman spectra were measured at room temperature at frequencies of 100–3000 cm–1. Heterovalent substitution of Sn4+ for Cr3+ modifies the spectra of pure Bi2Sn2O7. The crystal structure of Bi2Sn2O7 consists of two oxygen sublattices: SnO6 and Bi2O'. Chromium ions substituted tin ions in the SnO6 oxygen octahedra, distorting the local structure in the vicinity of bismuth ions. Phonon modes are softening in the vicinity of phase transitions. А shift of the phase boundaries of polymorphic transitions is observed for Bi2(Sn1-хCrх)2O7, x = 0.05, 0.1. The frequencies of stretching vibration modes were determined from IR and Raman spectra. The substitution of chromium for tin ions resulted in the appearance of two new modes at frequencies of 581 and 822 cm–1 in the Raman spectra. The absence of an inversion center in the crystal structure of Bi2(Sn1-xCrx)2O7 is confirmed by Raman spectroscopy. IR spectra of chromium-substituted samples consist of complex lines, which decompose into 2 and 3 Lorentzian lines. The softening and broadening of optical absorption modes are associated with the electronic contribution. Impurity states of electrons form polarons.Методом твердофазной реакции синтезированы хромзамещенные пиростаннаты висмута со структурой пирохлора. Рентгеноструктурный анализ, выполненный при комнатной температуре, показал, что образцы Bi2(Sn1-хCrх)2O7, х = 0; 0,05, 0,1 однофазные и принадлежит к моноклинной структуре Pc. Полиморфные превращения синтезированных образцов изучались методами Раман и ИК спектроскопии. ИК-спектры получены в температурном диапазоне 110-525 К, интервале частот 350-1100 см-1. Спектры Рамановского рассеяния измерялись при комнатной температуре на частотах 100-3000 см-1. Гетеровалентное замещение Sn4+ на Cr3+ видоизменяет спектры чистого Bi2Sn2O7. Кристаллическая структура Bi2Sn2O7 состоит из двух кислородных подрешеток: SnO6 и Bi2O′. Ионы хрома замещают ионы олова в кислородных октаэдрах SnO6, искажая локальную структуру в окрестности ионов висмута. Вблизи фазовых переходов происходит смягчение фононных мод. Для Bi2(Sn1-хCrх)2O7, 0,05, 0,1 наблюдается смещение фазовых границ полиморфных переходов. Из ИК и Раман спектров определены частоты мод валентных колебаний. В Рамановских спектрах замещение ионов олова хромом привело к появлению двух новых мод на частотах 581 и 822 см-1. Отсутствие центра инверсии в кристаллической структуре Bi2(Sn1-хCrх)2O7 подтверждается Раман спектроскопией. ИК спектры хромзамещенных образцов состоят из сложных линий, которые разлагаются на 2 и 3 линии Лоренцовой формы. Смягчение и уширение спектров поглощения связывается с электронным вкладом. Примесные состояния электронов образуют поляроны.
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13.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Zobov V. E., Moskvich Yu. N., Ponomarenko A. V.
Заглавие : Nonequidistant multipulse sequence for study of slow atomic motions in solids
Коллективы : Soviet-indian symposium on actual problems of magnetic resonance spectroscopy of inorganic materials, Академия наук СССР, Indian national academy of sciences, Академия наук Таджикской ССР
Место публикации : Proceedings of the 1st soviet-indian symposium on actual problems of magnetic resonance spectroscopy of inorganic materials. - Dushanbe, 1982. - P.204-205
Примечания : Библиогр.: 5
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Karavaysky A. Yu.
Заглавие : Shielded open-circuited probe for in-situ measurements of soil permittivity in Very high frequency (VHF) and Ultra high frequency (UHF) bands
Коллективы : SB RAS project [0287-2021-0034]
Место публикации : Trans. Inst. Meas. Control. - 2021. - Vol. 43, Is. 16. - P.3566-3572. - ISSN 0142-3312, DOI 10.1177/01423312211037791. - ISSN 1477-0369(eISSN)
Примечания : Cited References: 30. - The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the SB RAS project No. 0287-2021-0034
Предметные рубрики: DIELECTRIC CHARACTERIZATION
MOISTURE
Аннотация: In this paper, the shielded open-circuited probe operating in the wide frequency range from 75MHz to 2GHz is proposed. The probe is made of an SubMiniature version A (SMA) flange connector. The central rod of the SMA connector emerges from a coaxial transition in the flange and shielded by four rods. The robe design allows us to calculate of the probe reflection coefficient S11 used simple analytical transmission line model (TEM wave mode), the parameters of which were calibrated on a set of substances with a known frequency spectrum of permittivity. The refractive index (RI) and normalized attenuation coefficient (NAC) retrieval technique is based on solving the inverse problem of minimizing the residual norm between measured and calculated frequency spectra of reflection coefficient S11. After calibration, the root-mean-square error (determination coefficient) between the measured and calculated module and phase of the reflection coefficient S11 for the sets of calibration media air, distilled water, butanol, pure ice, water solution with NaCl of salinity of 8.9% do not exceed 0.26dB (0.995) and 0.03 rad (0.999), respectively, in the frequency range from 75MHz to 2GHz. The root-mean-square error (determination coefficient) between the measured RI and NAC spectra for four soil cover samples (variation of the clay fraction from 10.5 g/g to 47.6 g/g) using the proposed probe and a precision coaxial cell not exceeds 0.109 (0.993) and 0.057 (0.986), respectively, in the frequency range from 75 MHz to 2 GHz. As a result, it is experimentally shown that RI и NAC can be measured by the proposed non-precision probe with an error comparable to the precision coaxial cell.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shetty P. P., Maksimov D. N., Babu M., Bongu S. R., Bingi J.
Заглавие : Thermo-optic refraction based switchable optical mode converter
Место публикации : J. Quant. Spectrosc. Radiat. Transf. - 2021. - Vol. 274. - Ст.107867. - ISSN 00224073 (ISSN), DOI 10.1016/j.jqsrt.2021.107867
Примечания : Cited References: 30. - Authors acknowledge the funding support from DST India under INT/RUS/RFBR/P-262
Аннотация: The temporally switchable optical mode conversion is crucial for optical communication and computing applications. This research demonstrates such optically switchable mode converter driven by thermo-optic refraction. The MoS2 nanofluid is used as a medium where the thermal microlens is created by a focused laser beam (pump). The convective thermal plume generated above the focal point of the pump beam within the nanofluid acts as an astigmatic thermal lens. It is discovered that mode conversion of the Laguerre-Gaussian (LG) to the Hermite-Gaussian (HG) beam (vice versa) takes place upon passing through the thermal lens. The topological charge of the LG beam can be easily determined using the proposed mode converter. The mode transformation is explained theoretically as the Fourier components of the LG beam undergoing different optical paths while propagating through the convective plume.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu. V., Balaev D. A., Stolyar S. V., Krasikov A. A., Bayukov O. A., Volochaev M. N., Yaroslavtsev R. N., Ladygina V. P., Velikanov D. A., Iskhakov R. S.
Заглавие : Interparticle magnetic interactions in synthetic ferrihydrite: Mossbauer spectroscopy and magnetometry study of the dynamic and static manifestations
Место публикации : J. Alloys Compd. - 2022. - Vol. 889. - Ст.161623. - ISSN 09258388 (ISSN), DOI 10.1016/j.jallcom.2021.161623
Примечания : Cited References: 84. - This study was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Territory, and the Krasnoyarsk Territorial Foundation for Support of Scientific and R&D Activities, project no. 19–42–240012 R-A “Magnetic Resonance in Ferrihydrite Nanoparticles: Effects Related to the Core-Shell Structure”
Аннотация: Samples of synthetic ferrihydrite with an average nanoparticle size of 2.7 nm have been examined by magnetometry and Mossbauer spectroscopy. Ferrihydrite is characterized by the antiferromagnetic interactions between the magnetic moments of iron atoms. In ferrihydrite nanoparticles, as in any other antiferromagnetic ones, structural defects induce the formation of an uncompensated magnetic moment, which determines the magnetic properties typical of single-domain ferro- and ferrimagnetic particles. The manifestation of the magnetic interactions between ferrihydrite nanoparticles in the magnetic properties of the material and in the temperature evolution of Mossbauer spectra has been in focus. The results obtained on synthetic ferrihydrite have been compared with the data for the biogenic ferrihydrite sample with a similar average size of particles surrounded by a polysaccharide shell, which weakens and screens the interparticle magnetic interactions. A clear manifestation of the effect of the interparticle magnetic interactions on the transition to the blocked state is the presence of a significant contribution of the relaxation component in the Mossbauer spectra at temperatures of the transition from the superparamagnetic to blocked state. The temperature dependence of the particle relaxation time obtained from the Mossbauer spectra points out the collective effect of freezing of the magnetic moments of particles due to the magnetic interactions between them.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gerasimova Yu. V., Aleksandrovsky A. S., Laptash N. M., Gerasimov M. A., Krylov A. S., Vtyurin A. N., Dubrovskiy A. A.
Заглавие : Spectroscopy of structurally disordered hydrated iron fluoridotitanate in the regions of vibrational and electronic excitations
Место публикации : Spectrochim. Acta A. - 2022. - Vol. 264. - Ст.120244. - ISSN 13861425 (ISSN), DOI 10.1016/j.saa.2021.120244
Примечания : Cited References: 28. - The reported study was funded by Russian Foundation for Basic Research, Government of Krasnoyarsk Territory and Krasnoyarsk Regional Foundation of Science according to the research project “Spectral and magnetic properties of single crystals of transition metal fluoride hexahydrates.” No. 20-42-240014
Аннотация: Raman and optical absorption spectra of disordered hydrated iron fluoridotitanate (HITF) single crystal were studied. Temperature transformations of the Raman spectra indicate independent ordering processes of the [TiF6]2− and [Fe(H2O)6]2+ complexes below the structural phase transition. The absorption spectrum in the near-infrared and visible ranges includes transitions from the high spin ground state 5T2 of Fe2+ ion to the excited 5E state and a set of excited triplets. Analysis by Tanabe-Sugano method gives crystal field Dq = 490 cm−1 and Racah parameters B = 340 cm−1 and C = 1904 cm−1. Considerable decrease of B parameter as compared to the free ion value indicates a decrease of interelectron repulsion in the disordered neighborhood of Fe2+ ions.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ruseikina A. V., Molokeev M. S., Chernyshev V. А., Aleksandrovsky A. S., Krylov A. S., Krylova S. N., Velikanov D. A., Grigoriev M. V., Maximov N. G., Shestakov N. P., Garmonov A. A., Matigorov A. V., Tarasov A. S., Rautskii M. V., Khritokhin N. А., Melnikova L. V., Tretyakov N. Y.
Заглавие : Synthesis, structure, and properties of EuScCuS3 and SrScCuS3
Место публикации : J. Solid State Chem. - 2021. - Vol. 296. - Ст.121926. - ISSN 00224596 (ISSN), DOI 10.1016/j.jssc.2020.121926
Примечания : Cited References: 72. - The work was supported by the Ministry of Science and Higher Education of the Russian Federation under Project No. FEUZ-2020-0054; by RFBR Grant 18-02-00754 ; by the “UMNIK” program research project № 14977GY/2019; by the Ministry of Science and Higher Education of the Russian Federation (contract no. 05.594.21.0019 , unique identification number RFMEFI59420X0019). Maxim S. Molokeev, Anton S. Tarasov and Mikhail V. Rautskii acknowledge additional funding from Research Grant No. 075-15-2019-1886 from the Government of the Russian Federation. The subset research was performed in Research Resource Center “Natural Resource Management and Physico-Chemical Research.” The use of equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center « Krasnoyarsk Science Center SB RAS» is acknowledged
Аннотация: The crystal structures of the first-synthesized compound EuScCuS3 and previously known SrScCuS3 are refined by Rietveld analysis of X-ray powder diffraction data. The structures are found to belong to orthorhombic crystal system, space group Cmcm, structural type KZrCuS3, with a = 3.83413(3) Å, b = 12.8625(1) Å, c = 9.72654(8) Å (SrScCuS3) and a = 3.83066(8) Å, b = 12.7721(3) Å, c = 9.7297(2) Å (EuScCuS3). The temperatures and enthalpies of incongruent melting are the following: Тm = 1524.5 К, ΔHm = 21.6 kJ•mol−1 (SrScCuS3), and Тm = 1531.6 К, ΔHm = 26.1 kJ•mol−1 (EuScCuS3). Ab initio calculations of the crystal structure and phonon spectrum of the compounds were performed. The types and wavenumbers of fundamental modes were determined and the involvement of ions participating in the IR and Raman modes was assessed. The experimental IR and Raman spectra were interpreted. EuScCuS3 manifests a ferromagnetic transition at 6.4 K. The SrScCuS3 compound is diamagnetic. The optical band gaps were found to be 1.63 eV (EuScCuS3) and 2.24 eV (SrScCuS3) from the diffuse reflectance spectra. The latter value is in good agreement with that calculated by the DFT method. The narrower band gap of EuScCuS3 is explained by the presence of 4f-5d transition in Eu2+ ion that indicates a possibility to control the band gap of the chalcogenides by the inclusion of Eu. The activation energy of crystal structure defects, being the source of additional absorption in the NIR spectral range, was found to be 0.29 eV.
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19.

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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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Немцев И. В., Шабанова О. В., Тамбасов, Игорь Анатольевич, Иваненко, Александр Анатольевич, Зырянов, Виктор Яковлевич
Заглавие : Опалоподобные структуры на основе субмикросфер полиметилметакрилата
Место публикации : Ученые зап. физ. фак-та МГУ. - 2020. - № 5. - Ст.2050101. - ISSN 2307-9665 (eISSN)
Примечания : Библиогр.: 18
Аннотация: В данной работе методом самосборки из частиц полиметилметакрилата субмикронного размера с полидисперсностью менее 5% изготовлены двумерные и трехмерные метаматериалы - коллоидные кристаллы. Морфологические особенности полученных образцов исследованы на сканирующем электронном микроскопе сверхвысокого разрешения FE-SEM Hitachi S-5500. Три различные области поверхности трехмерного опала исследованы с помощью спектроскопии отраженного света с угловым разрешением. Измерения спектров проводились в диапазоне 400-1250 нм. Вышеуказанными методами обнаружена высокоупорядоченная структура. Выявлено узкое гранулометрическое распределение частиц. Определены средний диаметр частиц, плотность упаковки, добротность и отражательная способность образцов. На основе экспериментальных спектров отражения выполнена аппроксимация зависимости максимальной длины волны отражательной способности от угла, используя модифицированный закон Брэгга-Снеллиуса. На основании данной зависимости определены длина волны максимума отражения при нормальном падении, диаметр частиц и плотность упаковки. Рассчитана длина волны центра фотонной запрещенной зоны для высокоупорядоченной поверхности при нормальном падении. Экспериментально измеренная полная ширина пика на полувысоте для наилучшего образца составила 70 нм, а добротность - 12.4. Рассчитанный коэффициент заполнения для высокоупорядоченного опала составил 87 %. Средний диаметр частиц, полученный при помощи аппроксимации спектров отражения, отлично согласуется со значениями, полученными с помощью электронной микроскопии. Наиболее интересный результат заключается в том, что отражающая способность поверхности при нормальном падении света может достигать 98 %, и эта величина зависит от коэффициента заполнения - плотности упаковки.In this paper, 2D and 3D metamaterials based on colloidal crystals are made from submicron-sized polymethylmethacrylate particles with a polydispersity of less than 5%. Morphological features of the obtained samples were studied using an ultra-highresolution FE-SEM Hitachi S-5500 scanning electron microscope. Three different surface areas of a three-dimensional opal was investigated using spectroscopy of the reflected light with the angular resolution. The spectra were measured in the range of 400- 1250 nm. The above methods revealed a highly ordered structure. A narrow particle size distribution was revealed. The average particle diameter, packing density, q-factor, and reflectivity of the samples were determined. Based on the experimental reflection spectra, the dependence of the maximum reflectivity wavelength on the angle is approximated using the modified Bragg-Snell law. Based on this dependence, the wavelength of the maximum reflection at normal incidence, the particle diameter, and the packing density are determined. The wavelength of the center of the photonic band gap is calculated for a highly ordered surface at normal incidence. The experimentally measured full width of the peak at half-height for the best sample was 70 nm, and the q factor was 12.4. The calculated filling factor for the highly ordered opal was 87%. The average particle diameter obtained by approximating the reflection spectra is in perfect agreement with the values obtained by electron microscopy. The most interesting result is that the reflectivity of the surface at normal light incidence can reach 98%, and this value depends on the filling factor the density of the package.
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