共查询到20条相似文献,搜索用时 15 毫秒
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K.R. Allahverdiev S.S. Babaev E.Yu. Salaev M.M. Tagyev E.A. Vinogradov A.F. Goncharov N.N. Melnick S.I. Subbotin V.V. Panfilov 《Solid State Communications》1980,35(9):705-708
Raman-active lattice vibrational modes of GaTe have been investigated at 300 K in the range 15–300 cm?1 in equilibrium conditions under different hydrostatic pressures up to 11.25 kbar. The spectra of the Bridgman grown crystals were excited with the 1.06 μm line of the continuously operated YAG:Nd3+ laser. The mode-Grüneisen parameters were determined for all fourteen Raman bands observed. It is shown that there is no low frequency rigid-layer modes or Davydov pairs in Raman spectra of GaTe crystals. 相似文献
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Resonant Raman spectra of γ-rich InSe have been measured at the absorption peak, E'1, which lies 1.2 eV above the lowest direct gap. The resonance behaviors observed indicate that the E'1 peak is due to the formation of damped M0 excitons. 相似文献
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The results of resonant Raman scattering experiments on trans-poly-acetylene under hydrostatic pressure are reported. The measurements were performed in a diamond anvil cell. The spectra could be measured up to 44 kbar. The pressure dependence of the 1295 cm-1 line was measured in a sapphire cell up to 17 kbar. The results show that the changes in the phonon frequencies are very small. By comparing the pressure dependence of the Raman bands with their dependence on the photon energy of the exciting laser line it is possible to determine the pressure variation of the electronic energy gap. The results are consistent with previous measurements of the absorption spectrum under hydrostatic pressure which were carried out up to 13.5 kbar. The gap is found to decrease rapidly with pressure but the decrease tends to saturate at high pressures. The results are consistent with a model in which chain-chain interaction plays a dominant role. 相似文献
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Takeo Ishidate Kuon Inoue Kazuhiko Tsuji Shigeru Minomura 《Solid State Communications》1982,42(3):197-200
The first studies on the pressure dependences of the first-order Raman spectra in plasma-deposited a-Si:H films are reported. With increasing pressure up to 25 kbar the TO optical phonon band shows a shift in peak to higher frequencies with a sharpening of width while the TA acoustic phonon band shows a shift in peak to lower frequencies with a broadening of width. The LO optical phonon band shows a shift in peak to higher frequencies whereas the LA acoustic phonon band remains unchanged. These pressure effects are discussed with changes in force constant and structural disorder. The alloying effect of H atoms on the Raman spectra is also discussed while comparing the pressure effects. 相似文献
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《Journal of Physics and Chemistry of Solids》2003,64(9-10):1597-1601
The Raman scattering spectra of ZnGa2Se4 under pressure were investigated at 300 K up to 18.9 GPa. Two stages were observed in the pressure dependences of Raman bands. Such behavior in accordance with the experimental findings existing in literature and was attributed as arising due to the order–disorder phase transition in the cation sublattice.Using the Harrison–Keating's model of the lattice dynamics modified for the crystals with the tetragonal structure, the bulk modulus B and the mode-Grüneisen parameters Γi were determined for the first time. It is shown that a better agreement between the experimental and calculated values of Γi is observed, if one takes into consideration different frequency-pressure behavior for the bond-bending and the bond-stretching parameters, which determine the low- (lower than 140 cm−1) and high- (higher than 140 cm−1) frequency phonons, respectively. 相似文献
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Abstract We have investigated the high pressure behavior of InSe by x-ray powder diffraction and optical measurements. The rhombohedral γ-polytype of InSe (space group R3m) exhibits a strongly anisotropic compressibility characteristic of the layer-type structure. Mode Gruneisen parameters of intralayer modes have been determined by Raman scattering. At 10.3(5) GPa InSe undergoes a phase transition to the rocksalt structure, which remains stable up to at least 30 GPa. Optical reflectivity measurements show the cubic high pressure phase to have metallic character. 相似文献
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V. Kagalovsky B. Horovitz Y. Avishai 《Physica E: Low-dimensional Systems and Nanostructures》1998,1(1-4)
We study dynamics of electrons in a magnetic field using a network model with two channels per link with random mixing, while the intrachannel potential is periodic (non-random); the channels represent two spin states. We consider channel mixing as function of the energy separation of the two extended states, and show that the phase diagram is different from the standard quantum Hall diagram for random intrachannel potential. 相似文献
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Raman scattering is a versatile and powerful technique and has been widely used in modern scientific research and vast industrial applications. It is one of the fundamental experimental techniques in condensed matter physics, since it can sensitively probe the basic elementary excitations in solids like electron, phonon, magnon, etc. The application of extreme conditions(low temperature, high magnetic field, high pressure, etc.) to Raman scattering, will push its capability up to an unprecedented level, because this enables us to look into new quantum phases driven by extreme conditions, trace the evolution of the excitations and their coupling, and hence uncover the underlying physics. This review contains two topics.In the first part, we will introduce the Raman facility under extreme conditions, belonging to the optical spectroscopy station of Synergetic Extreme Condition User Facilities(SECUF), with emphasis on the system design and the capability the facility can provide. Then in the second part we will focus on the applications of Raman scattering under extreme conditions to a variety of condensed matter systems such as superconductors, correlated electron systems, charge density waves(CDW) materials, etc. Finally, as a rapidly developing technique, time-resolved Raman scattering will be highlighted here. 相似文献
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The Raman spectrum of InSe was taken at room temperature and at liquid nitrogen temperature. We found that the TO (199 cm?1) and LO (212 cm?1) modes, together with their overtones and combinations at 400, 416 and 423 cm?1 disappeared at lower temperatures. We attribute the vanishing of these modes at low temperatures to a change of phase from ? to β polytype. 相似文献
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Abstract We report on high density photoluminescence (HDPL) measurements in undoped indium selenide under pressure at 300 K. Direct electron-hole plasma (DEHP) stimulated emission, induced by high density excitation, has been observed in InSe from room pressure up to 5.1 GPa. Spontaneous and stimulated emission bands observed in the spectra have been analyzed within the framework of the band gap renormalization theory (BGR) in a multi-valley scenario. The pressure coefficients of the spontaneous and stimulated emission bands have led us to attribute these bands to transitions from different minima in the conduction band, which show different renormalization energies determined by the effective masses and electron densities in each valley. Under high excitation, the direct to indirect crossover is shown to occur at a lower pressure than that observed in absorption measurements, as a result of the different renormalization energies of each transition. 相似文献
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I. V. Aleksandrov A. P. Goncharov I. N. Makarenko A. N. Zisman E. V. Jakovenko S. M. Stishov 《高压研究》2013,33(5-6):333-336
Abstract The development of the diamond-anvil cell has stimulated Raman-scattering investigation of vibrational modes in covalent crystals. The linear pressure coefficient reported for diamond by Hanfland et at' (2.90 ± 0.05 cm-1/GPa) agrees to within mutual experimental error with the result of Boppard et aL2 (2.87±0.01 cm-1/GPa). As to cubic boron nitride, the only work by Sanjurjo ef aL3 reports 3.45 ± 0.07 cm-1/GPa for LO- and 3.39 ± 0.08 cm-1/GPa for TO- modes. Since no compressibility data are availablel1?3, the mode Griineisen parameter γ = ‐ δ In γ/δ is defined as y = K/Y·dv/aP and depends on the bulk modulus K and the calibration of the ruby scale. The above papers report y= 0.96 and y=0.95±O.O3fordiamondand γLo=1.21,γTo=1.51 forBN. 相似文献
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《Solid State Communications》1986,58(11):789-793
The influence of crossed electric and magnetic fields on the intraband resonant contribution to Raman scattering is discussed. It is shown that in the presence of these fields, the Raman efficiency for one magnon process in ferromagnetic semiconductors exhibits two resonant peaks which are dependent on the ratio βE/Hβ. 相似文献
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L. P. Avakyants V. S. Gorelik É. M. Temper S. M. Shcherbina 《Physics of the Solid State》1999,41(8):1369-1372
Structure in the Raman scattering spectra of near-surface n-GaAs layers (n=2×1018 cm−3) implanted with 100 keV B+ ions in the dose range 3.1×1011–1.2×1014 cm−2 is investigated. The qualitative and quantitative data on the carrier density and mobility and on the degree of amorphization
of the crystal lattice and the parameters of the nanocrystalline phase as a result of ion implantation are obtained using
a method proposed for analyzing room-temperature Raman spectra.
Fiz. Tverd. Tela (St. Petersburg) 41, 1495–1498 (August 1999) 相似文献
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Summary The electron-phonon scattering in indium selenide single crystals has been investigated by Hall-mobility and Raman-spectroscopy
measurements. The experimental data have been interpreted according to the Fivaz and Schmid model for homopolar optical scattering.
The best fit of the experimental results is obtained by assuming the bidimensional behaviour of the interaction involving
anA
1
phonon with energy 14.5 meV. The bidimensional character is probably due to the presence of a large number of planar defects,
confirmed by electron microscope observations, which strongly localize the carriers within the layers.
Riassunto In questo lavoro è riportato uno studio dell'interazione elettrone-fonone in monocristalli di seleniuro di indio, condotto mediante misure di effetto Hall e spettroscopia Raman. I dati sperimentali sono stati interpretati secondo il modello di Fivaz e Schmid, per lo scattering da fononi ottici omopolari. L'approssimazione migliore delle curve sperimentali è ottenuta assumendo un carattere bidimensionale per l'interazione tra gli elettroni ed i fononi, nel modoA 1, con energia 14.5 meV. Il carattere bidimensionale delle proprietà di trasporto è probabilmente dovuto alla presenza di difetti planari che localizzano i portatori di carica all'interno degli strati.
Резюме Исследуется электрон-фононное рассеяние в монокристаллах InSe, используя измерения подвижности Холла и спектроскопии комбинационного рассеяния. Экспериментальые данные интерпретируются в соответствии с моделью Фиваца и Шмидта для гомополярного оптического рассеяния. Наилучшая подгонка экспериментальных результав получается в предположении двумерного характера взаимодействия между электронами и фононами, модыA 1 , с энергией 14.5 мэВ. Двумерный характер, по-видимому, обусуовлен наличием большого числа плоских дефектов, которые сильно локализуют носители внутри слоев, что подтверждается наблюдениями электронной микроскопии.相似文献