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Wyszukujesz frazę "78.30.j" wg kryterium: Temat


Tytuł:
Raman Analysis of Zn$\text{}_{1-x}$Mg$\text{}_{x}$Se Layers Grown on GaAs and ZnTe Substrates
Autorzy:
Renucci, M. A.
Frandon, J.
Głowacki, G.
Gapiński, A.
Rozpłoch, F.
Bała, W.
Powiązania:
https://bibliotekanauki.pl/articles/1952686.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
Opis:
A study of the Raman scattering in Zn$\text{}_{1-x}$Mg$\text{}_{x}$Se (0 ≤ x ≤ 0.4) epilayers grown by molecular beam epitaxy on (100) GaAs and (111)$\text{}_{Zn}$ ZnTe substrates has been performed. Two kinds of longitudinal optical phonon modes (LO$\text{}_{Zn-Se}$ and LO$\text{}_{Mg-Se}$) were observed under excitation of the Ar$\text{}^{+}$ and Kr$\text{}^{+}$ laser lines at room temperature, whose frequencies and intensities depend characteristically on the Mg content.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 1065-1069
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infrared Detectors - New Trends
Autorzy:
Piotrowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1872382.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
Opis:
Recent trends in infrared detectors are towards large, electronically addressed two-dimensional arrays and higher operating temperature. This will lead both to higher performance and to smaller, lighter and more affordable IR systems. Cooling requirements are the main obstacle to the more widespread use of infrared systems based on semiconductor photodetectors, particularly in the civil field. Fundamental limitations to performance of IR photodetectors are due to the statistical nature of generation-recombination processes and resulting noise. Ways to overcome the limitations are discussed including use of the optical immersion and optical resonant cavity. Finally, the progress in a mode of operation is presented, in which the thermal generation of carriers is suppressed by the use of stationary depletion of narrow gap semiconductors. The practical near room temperature narrow gap semiconductor photodetectors are reported. Competitive technologies based on Schottky barrier devices and low dimensional solids are considered briefly.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 303-316
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infrared Reflection of $MnTe_2$ under High Pressure
Autorzy:
Mita, Y.
Ishida, Y.
Kobayashi, M.
Endo, S.
Powiązania:
https://bibliotekanauki.pl/articles/1813955.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
78.30.-j
Opis:
The IR reflection measurements of $MnTe_2$ were performed at room temperature under various pressures. It is observed that the reflectivity increases at the pressure range of 8-25 GPa and becomes almost constant at the higher pressure. The carrier concentrations obtained from the reflectivity spectra at the highest pressure region are the order of $10^{22} cm^{-3}$. Therefore it is concluded that pressure-induced semiconductor-metal transition occurs at the pressure range of 8-25 GPa.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 617-620
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Models for the Analysis of~IR Reflectivity in $TlBiTe_2$ with Different Size of Twins
Autorzy:
Hatzikraniotis, E.
Powiązania:
https://bibliotekanauki.pl/articles/1491508.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Bh
78.30.-j
Opis:
In this work $TlBiTe_2$ were grown by a modified Bridgman technique and examined samples had different lateral dimensions of twins, ranging from 0.1 μm to 1 μm. The average lateral size of the twins seems to affect free carrier concentration and plasma frequency. Infrared spectra were analyzed by two models, the extended Drude model and a generalized empirical model of frequency-dependent damping factor. Increase in size of twins affects the electronic properties and hence plasma reflectivity and free carrier concentration of $TlBiTe_2$.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 284-286
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonance Raman Investigations of Low Energetic Modes in the Organic Superconductors α$\text{}_{t}$-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ and β-(BEDT-TTF)$\text{}_{2}$IAuI
Autorzy:
Ludwig, T.
Schweitzer, D.
Keller, H. J.
Powiązania:
https://bibliotekanauki.pl/articles/1933367.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
74.70.Kn
Opis:
A study of low energetic modes in the resonance Raman spectra of the organic superconductors α$\text{}_{t}$-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ (T$\text{}_{c}$ = 8 K) and β-(BEDT-TTF)$\text{}_{2}$IAuI (T$\text{}_{c}$ = 4 K) in the temperature range of 1.5-100 K was performed. In both materials, a strong vanishing of low energetic phonon bands (at 30 cm$\text{}^{-1}$ and 40 cm$\text{}^{-1}$ for α$\text{}_{t}$-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ and at 27 cm$\text{}^{-1}$ and 33 cm$\text{}^{-1}$ for β-(BEDT-TTF)$\text{}_{2}$IAuI) below 71 was observed. For the symmetric stretching mode of the I¯$\text{}_{3}$ and the IAuI¯ anion at 120 cm$\text{}^{-1}$ no change below T, was found. In addition, wavelength dependent measurements on α-(BEDT-TTF)$\text{}_{2}$I$\text{}_{3}$ were performed, indicating that the modes around 30 cm$\text{}^{-1}$ are probably librational modes of the BEDT-TTF molecules.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 801-806
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selective Resonance Raman Scattering of Peierls-Hubbard (TTF$\text{}^{+}$)$\text{}_{2}$ Dimers in (TTF)$\text{}_{2}$Mo$\text{}_{6}$O$\text{}_{19}$ and (TTF)$\text{}_{2}$W$\text{}_{6}$O$\text{}_{19}$ Salts
Autorzy:
Kruszewski, S.
Feltre, L.
Bozio, R.
Bellitto, C.
Powiązania:
https://bibliotekanauki.pl/articles/1929169.pdf
Data publikacji:
1993-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
34.70.+e
78.30.-j
Opis:
Raman investigation of Peierls-Hubbard (TTF$\text{}^{+}$)$\text{}_{2}$ dimers in (TTF)$\text{}_{2}$Mo$\text{}_{6}$O$\text{}_{19}$ and (TTF)$\text{}_{2}$W$\text{}_{6}$O$\text{}_{19}$ salts have been performed. It was found that the resonance enhancement of Raman intensity of intramolecular vibration modes exists only when the frequency of excitation light fits to the localised electron transition, however, the resonance enhancement of intermolecular modes occurs when the frequency of excitation light corresponds to the charge transfer transition.
Źródło:
Acta Physica Polonica A; 1993, 83, 4; 431-440
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of Tomato Juice Quality Using Surface Enhanced Raman Spectroscopy
Autorzy:
Malekfar, R.
Nikbakht, A.
Abbasian, S.
Sadeghi, F.
Mozaffari, M.
Powiązania:
https://bibliotekanauki.pl/articles/1537806.pdf
Data publikacji:
2010-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
33.20.Fb
Opis:
Tomato (Lycopersicon esculentum L.) is a valuable fruit cultivated in the world as an important plant. There are a lot of industries engaged with the drying, processing, quality control and sorting of tomato. A rapid and reliable measurement of qualitative factors of tomato and its products can be a serious necessity for the producers and industrialists. The objective of this research was to implement SERS as a modern technique to evaluate some qualitative parameters of tomato juice. To prevent the effect of cartenoids and florescence background, the juices were centrifuged. Silver colloid was prepared according to Lee and Meisel method for SERS experiments. The results were compared with the spectra obtained from ordinary spontaneous Raman spectroscopy technique data. Three major bands assigned to carbohydrates in tomato were detected and analyzed. Moreover, a medium band related to proteins could be identified. Comparison of SERS spectra with the normal spontaneous Raman spectra proved that SERS has a privilege in the measurement of carbohydrates and proteins as an effective, rapid and precise technique.
Źródło:
Acta Physica Polonica A; 2010, 117, 6; 971-973
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of Infrared Transition Spectrum of Synchrotron Radiation Through Superconducting YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ Film
Autorzy:
Tyutyunnikov, S. I.
Shaliapin, V. N.
Scintee, N.
Powiązania:
https://bibliotekanauki.pl/articles/1964055.pdf
Data publikacji:
1997-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.76.+w
78.30.-j
Opis:
This paper presents measurement results of the synchrotron radiation infrared transmission spectrum through YBCO film on MgO substrate at T=20 K temperature. The film's transmission temperature of the superconducting state is T$\text{}_{c}$=80 K. During formation cycle the maximum intensity wavelength varies from 100 μm to 10 μm. Due to spectrum evolution the detector signal that gives synchrotron radiation sample transmission is related to the sample transmission ability, the sensitivity of the detector and synchrotron radiation spectrum via an integral equation. The best agreement with experiment results is achieved for the Eγ=20 meV energy gap value, which corresponds to 2Eγ/kT$\text{}_{c}$=2.9 at T=20 K.
Źródło:
Acta Physica Polonica A; 1997, 91, 5; 893-897
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering and Electrical Properties of TGS:PCo (9%) Crystal as Ambient Temperature IR Detector
Autorzy:
Malekfar, R.
Daraei, A.
Powiązania:
https://bibliotekanauki.pl/articles/1812050.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
77.84.Fa
Opis:
We developed and adequately characterized the triglycine sulfate family crystals doped with specific molar percent of cobalt phosphate, TGS:PCo (9%). The crystals were grown by slow evaporation technique and the growth rates of different crystallographic planes are rather faster in comparison with the plane growth rates of pure TGS crystals. The introduction of $Co^{2+}$ ion as an active optical element to the structure of TGS crystal leads to optimization of some parameters such as optical quality, stability at ambient condition, Curie temperature, stronger Raman peaks, etc. Three new peaks at 460, 620 and 1368 $cm^{-1}$ were observed in the dispersive back scattering Raman spectra of the grown TGS:PCo (9%) crystal in comparison with the pure triglycine sulfate crystal.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 859-867
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Imaging Approach to the Study of Ferroelectric Domains and Raman Spectra of Multiferroic Boracites
Autorzy:
Iliev, M.
Hadjiev, V.
Íñiguez, J.
Pascual, J.
Powiązania:
https://bibliotekanauki.pl/articles/1807797.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
77.84.Bw
Opis:
The boracites with general formula $M_3B_7O_{13}X$ (M = divalent metal, X = Cl, Br, I), shortly denoted as M-X, are among the first known multiferroic materials. They exhibit a sequence of transitions from the high temperature paraelectric cubic phase to ferroelectric orthorhombic, monoclinic, trigonal phases, and finally to a monoclinic phase at low temperatures, where both ferroelectric and magnetic orders coexist. The lattice dynamics of boracites has been scarcely studied with the Raman spectroscopy, the main problem with non-cubic phases being the coexistence of twin variants with different crystallographic and polarization orientation. In this work, on the example of $Co_3B_7O_{13}Cl (Co-Cl)$, $Co_3B_7O_{13}Br (Co-Br)$ and $Ni_3B_7O_{13}Br (Ni-Br)$ we demonstrate that using the Raman microscopy imaging one can visualize the twin variants, follow their transformation through the crystallographic transitions, obtain Raman spectra from untwinned domains in exact scattering configurations, determine the Raman mode symmetries, and assign Raman lines to definite atomic motions. The effects of structural transitions and elemental substitution are discussed in close comparison with results of ab initio calculations of the phonon structure of the cubic phase.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 19-24
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Spectra and Structural Data of the Nanocrystalline KTP $(KTiOPO_4)$ Synthesized by Pechini Method
Autorzy:
Malekfar, R.
Cheraghi, A.
Ahmadi, G.
Khanzadeh, M.
Powiązania:
https://bibliotekanauki.pl/articles/1585099.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.-j
77.84.Fa
Opis:
Nanocrystalline KTP powders are synthesized using a modified Pechini method. The structural and lattice modes of the products are investigated via X-ray diffraction, micro Raman backscattering spectroscopy, UV/vis/NIR and FT-IR transmission spectroscopy. The Debye-Scherrer formula is used to confirm the grain sizes estimated by the scanning electron microscopy slides.
Źródło:
Acta Physica Polonica A; 2009, 116, 6; 1073-1075
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monotropic Character of Polymorphism in Pentachloropyridine Crystal Studied by Calorimetric and Spectroscopic Methods
Autorzy:
Wójcik, G.
Giermańsκa-Kahn, J.
Marqueton, Y.
Foulon, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933583.pdf
Data publikacji:
1995-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
78.30.-j
Opis:
Pentachloropyridine crystals in two polymorphic modifications: tetragonal and monoclinic were studied by differential scanning calorimetry and polarized IR and Raman spectroscopy in 20 to 200 cm$\text{}^{-1}$ region and at different temperatures from melting point down to the liquid nitrogen temperature. The 4 K difference in melting points of both forms indicates the occurrence of monotropy. The spectra were discussed in terms of positional disorder in the studied crystals which often happen to be mixtures of the monoclinic crystal and the L- and D-forms of the tetragonal one. The monotropic transition of the metastable tetragonal crystal into the stable monoclinic one was observed in the Raman spectra and under the polarizing microscope at temperatures ranging from 170 to 185 K and as an anomaly on the differential scanning calorymetry diagram at 193 K.
Źródło:
Acta Physica Polonica A; 1995, 88, 2; 339-347
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Dependence of the First-Order Raman Phonon Lines in GaS$\text{}_{0.25}$Se$\text{}_{0.75}$ Layered Crystals
Autorzy:
Gasanly, N. M.
Powiązania:
https://bibliotekanauki.pl/articles/2035649.pdf
Data publikacji:
2002-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
78.30.-j
78.30.Hv
Opis:
Systematic measurements by Raman scattering of the frequency and line width of the zone-center optical modes in GaS$\text{}_{0.25}$Se$\text{}_{0.75}$ layered crystal over the temperature range of 10-300 K are carried out. The analysis of temperature dependence of intralayer modes shows that frequency shift and line broadening are successfully modeled by including the contributions from thermal expansion and lattice anharmonicity. The purely anharmonic contribution (phonon-phonon coupling) is found to be due to three-phonon processes.
Źródło:
Acta Physica Polonica A; 2002, 102, 6; 801-810
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Raman Scattering in TlGa$\text{}_{x}$In$\text{}_{1-x}$S$\text{}_{2}$ Layered Mixed Crystals: Compositional Dependence of the Mode Frequencies and Line Shapes
Autorzy:
Gasanly, N. M.
Yuksek, N. S.
Powiązania:
https://bibliotekanauki.pl/articles/2044573.pdf
Data publikacji:
2005-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
78.30.Hv
78.30.-j
Opis:
The Raman spectra of TlGa$\text{}_{x}$In$\text{}_{1-x}$S$\text{}_{2}$ layered mixed crystals were studied for a wide range of composition (0≤x≤1) at T=50 K. The effect of crystal disorder on the line width broadening of the Raman-active modes are discussed. The asymmetry in the Raman line shape is analyzed for two interlayer and intralayer modes exhibiting one-mode behavior.
Źródło:
Acta Physica Polonica A; 2005, 108, 6; 997-1003
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Mn-Doped $BiFeO_3$ Nanoparticles
Autorzy:
Fukumura, H.
Matsui, S.
Tonari, N.
Nakamura, T.
Hasuike, N.
Nishio, K.
Isshiki, T.
Harima, H.
Kisoda, K
Powiązania:
https://bibliotekanauki.pl/articles/1807808.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Hv
63.20.D-
78.30.-j
Opis:
$BiFeO_3$ is a multiferroic material showing antiferromagnetic ordering and ferroelectric behavior simultaneously. Here, Mn-doped $BiFeO_3$ nanoparticles were synthesized up to 10% of Mn composition by a sol-gel process. The samples showed high crystallinity with no secondary phase up to 2% of Mn doping. A phonon peak at 1250 $cm^{-1}$ in undoped $BiFeO_3$ showed anomalous intensity enhancement in the magnetically ordered phase below $T_N$ = 643 K due to a spin-phonon coupling. This behavior was less pronounced in the Mn-doped samples, suggesting a suppression of magnetic ordering between $Fe^{3+}$ spins by Mn doping.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 47-50
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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