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Wyświetlanie 1-12 z 12
Tytuł:
Differential Reflection Spectroscopy: A Novel Method for Explosive Detection
Autorzy:
Yuksel, S.
Dubroca, T.
Hummel, R.
Gader, P.
Powiązania:
https://bibliotekanauki.pl/articles/1399730.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Gz
78.90.+t
Opis:
In the aftermath of the recent terrorist attacks, there has been an increasing need for automated, high-speed detection technologies that can detect trace amounts of explosives without human intervention. Our group at the University of Florida has developed differential reflection spectroscopy which can detect explosive residue on surfaces such as parcel, cargo and luggage. In this differential reflection device, explosives show spectral finger-prints at specific wavelengths, for example, the spectrum of 2,4,6, trinitrotoluene shows an absorption edge at 420 nm. Additionally, we have developed a support vector machine based computer software to classify the explosives and non-explosive materials. In this study we will (i) describe this system and give an insight into the operation of our prototype, (ii) demonstrate our software for the detection of the spectral finger-prints, and (iii) discuss the normalization of the data which significantly increases classification rates and decreases the number of parameters.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 263-264
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering Study of (Sr,Ca)$\text{}_{10}$Cu$\text{}_{17}$O$\text{}_{29}$ Single Crystals
Autorzy:
Strzeszewski, J.
Szymczak, H.
Leonyuk, L.
Szymczak, R.
Powiązania:
https://bibliotekanauki.pl/articles/2014363.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Hv
74.25.Gz
74.25.-q
Opis:
Polarized Raman spectra of high temperature superconducting single crystals of A$\text{}_{10}$Cu$\text{}_{17}$O$\text{}_{29}$ (A$\text{}_{10}$=Ca$\text{}_{4.7}$Sr$\text{}_{4.1}$Bi$\text{}_{0.3}$) were studied in various scattering configurations in the range of 40-700cm$\text{}^{-1}$. In very distinctive spectra there were found over 20 peaks. It was observed that the flat continuum of electronic excitations in the normal state was redistributed below the critical temperature. The frequency dependent redistribution is consistent with the value of energy gap estimated using tunnelling spectroscopy techniques.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 429-439
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Behaviour of $(Nd_{0.33}Eu_{0.2}Gd_{0.47})Ba_2Cu_3O_{y}$ Studied by Infrared Measurements
Autorzy:
Rameš, M.
Železný, V.
Phuoc, V.
Gervais, F.
Wolf, T.
Jirsa, M.
Powiązania:
https://bibliotekanauki.pl/articles/1534787.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Gz
74.20.Mn
74.25.Kc
Opis:
Optical properties of a are $(Nd_{0.33}Eu_{0.2}Gd_{0.47})Ba_2$ $Cu_3O_y$ (NEG-123) single crystal interpreted in terms of the extended Drude model.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 938-939
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution from the BCS to the Bose-Einstein Limit in a d-Wave Superconductor at T=0
Autorzy:
Borkowski, L. S.
Sá de Melo, C. A. R.
Powiązania:
https://bibliotekanauki.pl/articles/2027398.pdf
Data publikacji:
2001-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.20.-z
74.25.Gz
67.40.Db
Opis:
We study the evolution from BCS to Bose limit in a two-dimensional d-wave superconductor at zero temperature and low density of charge carriers within the mean-field theory. We examine single quasiparticle properties when particle density and attraction strength are varied. For sufficiently high interaction strength there is a critical density below which the system has a gap. The spectral and thermodynamic properties of the system do not evolve smoothly from the BCS-like to the Bose-like regime.
Źródło:
Acta Physica Polonica A; 2001, 99, 6; 691-698
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantization of electromagnetic modes in a hyperbolic negative-index layered superconductor slab
Autorzy:
Cortés-López, S.
Pérez-Rodríguez, F.
Powiązania:
https://bibliotekanauki.pl/articles/1062050.pdf
Data publikacji:
2016-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Gz
74.25.N-
74.78.Fk
78.67.Pt
Opis:
We theoretically study the infrared reflectivity and transmissivity of a high-temperature layered superconductor slab. Both infrared spectra exhibit very narrow Fabry-Perot resonances associated with the quantization of the wave vector of the TM electromagnetic modes. The resonances are observed in a pass band where the refractive index of the layered superconductor is negative. The pass band of negative dispersion is above the Josephson plasma frequency which appears in the expression for the effective permittivity component, corresponding to the direction perpendicular to the layers. It was found that the Fabry-Perot resonances undergo a blue shift as the slab thickness or the angle of incidence are increased. Moreover, the quantized electromagnetic modes turn out to be quasi-longitudinal because of the strong anisotropy of the infrared dielectric response of the layered superconductor.
Źródło:
Acta Physica Polonica A; 2016, 130, 2; 641-644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Optoelectronic Properties of ZnS Nanostructured Thin Film
Autorzy:
Borah, J.
Sarma, K.
Powiązania:
https://bibliotekanauki.pl/articles/1812035.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.61.Tm
74.25.Gz
Opis:
ZnS nanocrystalline thin films were grown into the polyvinyl alcohol matrix and were synthesized by chemical route. Films were prepared on glass substrate by varying the deposition parameters and pH of the solution. Nanocrystalline thin film prepared under optimum growth conditions shows band gap value 3.88 eV as observed from optical absorption data. The band gap is found to be higher (3.88 eV) indicating blue shift. The particle size, calculated from the shift of direct band gap, due to quantum confinement effect is 5.8 nm. Photoluminescence spectrum shows the blue luminescence peaks (centered at 425 nm), which can be attributed to the recombination of the defect states. ZnS nanocrystalline thin films are also found to be photosensitive in nature. However, the photosensitivity decreases due to ageing and exposure to oxygen. In case of nanostructured film, the I-V characteristics are observed in dark and under illumination showing photosensitive nature of these films, too. The dark current, however, is found to be greater when observed in vacuum compared to air. Both dark current and photocurrent are found to be ohmic in nature up to a certain applied bias. The observed data shows that nanostructured films are found to be suitable for device application. The surface morphology of the film is also characterized by scanning electron microscope.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 713-719
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Responses in Asymmetric Inverse Parabolic Quantum Wells: Effects of Laser Fields and Hydrostatic Pressure
Autorzy:
Mora-Ramos, M.
Morales, A.
Duque, C.
Powiązania:
https://bibliotekanauki.pl/articles/1207558.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
73.63.Hs
73.21.-b
74.25.Gz
Opis:
We report the theoretical calculation of the electronic states in a $Al_{x}Ga_{1-x}As$-based quantum well with inverse parabolic confinement under the combined effects of the intense laser field and hydrostatic pressure. Calculations are in the effective mass and parabolic band approximations and using a variational procedure and the so-called Floquet method in order to obtain the energies and wave functions for the conduction band states. We use the obtained information to investigate the intersubband-related nonlinear optical absorption and optical rectification coefficients.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 202-204
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Substrate Temperature Influenced Structural and Electrical Behaviour of~RF Magnetron Sputtered $Ag_2Cu_2O_3$ Films
Autorzy:
Sreedhar, A.
Hari Prasad Reddy, M.
Uthanna, S.
Martins, R.
Elangovan, E.
Pierson, J.
Powiązania:
https://bibliotekanauki.pl/articles/1492600.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.-b
71.15.Mb
78.20.Ci
74.25.Gz
Opis:
$Ag_2Cu_2O_3$ films were deposited on glass and silicon substrates by RF magnetron sputtering of metallic equimolar $(Ag_{50}Cu_{50})$ alloy target in $Ar-O_{2}$ mixture at different substrate temperature $(T_{s})$ ranging between 303 and 523 K. The effect of $T_{s}$ on the core level binding energies, structural and electrical properties of the films was systematically studied. The films deposited at room temperature were amorphous. The films deposited at 373 K were polycrystalline and the crystallinity was increased when the $T_{s}$ was increased to 423 K. The films deposited at 423 K and subsequently annealed at 498 K exhibits single phase $Ag_2Cu_2O_3$. In the case of films deposited at higher $T_{s}$ of 523 K, $Ag_2O$ was decomposed into Ag. The electrical resistivity of the films deposited at 303 K was $1.2 \times 10^{-5}$ Ω cm, whereas the films formed at 423 K and subsequently annealed at 498 K showed electrical resistivity of $2.2 \times 10^{-3}$ Ω cm due to improvement in the crystallinity of single phase $Ag_2Cu_2O_3$.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-037-A-039
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Properties of Manganese Doped CdS Nanoparticles under Various Synthesis Conditions
Autorzy:
Salimian, S.
Farjami Shayesteh, S.
Powiązania:
https://bibliotekanauki.pl/articles/1535741.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
74.25.Gz
78.55.Et
81.16.Be
Opis:
An aqueous solution method has been developed for synthesizing size-controlled $Mn^{2+}$ doped CdS nanocrystals with a relatively narrow size distribution. The nanocrystal samples were characterized by UV-Vis absorption spectra and photoluminescence spectra. We prepared narrow size distribution particles under different synthesis conditions. The effect of manganese concentration on the photoluminescence properties was investigated. Luminescence intensity in different excitation wavelength correlates with different size of CdS:Mn nanocrystals on luminescence spectra. We found that by narrowing the size distribution and doping concentration, CdS samples can be prepared with high luminescence intensity.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 633-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interpretation of Switching Properties of $InGaSe_2$ Single Crystal
Autorzy:
Al Orainy, R.
Powiązania:
https://bibliotekanauki.pl/articles/1489875.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
78.66.-w
73.61.Ga
74.25.Gz
Opis:
The goal of this paper is to present experimental results of the switching effect and analyze qualitatively the influence of various factors, such as temperature, light illumination and sample thickness on switching behavior of the high quality ternary chalcogenide semiconductor $InGaSe_2$. Current-controlled negative resistance of $InGaSe_2$ single crystals has been observed for the first time. It has been found that indium gallium diselenide single crystals exhibit bistable or memory switching. The switching process takes place with both polarities on the crystal and has symmetric shapes. Current-voltage characteristics of $Ag-InGaSe_2-Ag$ structures exhibit two distinct regions, high resistance OFF state and low-resistance ON state having negative differential resistance. $InGaSe_2$ is a ternary semiconductor exhibiting S-type I-V characteristics. The specimen under test showed threshold switching with critical field of the switching being $10^3$ V/cm at room temperature.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 666-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electro-Optical Properties of II-VI Superlattices
Autorzy:
Schillak, P.
Czajkowski, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047684.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.Cc
73.21.Cd
74.25.Gz
78.20.Jq
78.67.-n
Opis:
We show how to compute electro-optical spectra of semiconductor superlattices in the region of interband electronic transitions. The method uses the microscopic calculation of eigenvalues and eigenfunctions and the macroscopic real density matrix approach to compute the electromagnetic fields and susceptibilities. The electron-hole screened Coulomb potential is adapted and the valence band structure is taken into account in the cylindrical approximation, thus separating light- and heavy-hole motions. We calculate the electro-optical functions, including the optical Stokes parameters and ellipsometric functions for the case of oblique incidence. Results are given for Zn$\text{}_{1-x}$Cd$\text{}_{x}$Se/ZnSe superlattices and a good agreement with experiments is obtained.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 301-304
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Ferromagnetic Layer on Critical Current of a Superconducting Wire
Autorzy:
Gömöry, F.
Vojenčiak, M.
Šouc, J.
Seiler, E.
Powiązania:
https://bibliotekanauki.pl/articles/1813946.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Gz
74.25.Fy
74.25.Nf
Opis:
We investigated how a 10-50 μm layer from soft ferromagnetic material, incorporated in the architecture of a composite superconducting tape, could influence the capability of the tape to transport electrical current. Numerical procedure was developed to calculate the local distribution of magnetic field and current in the condition when all the superconductor is carrying its critical current density. It was found that the concentration of magnetic flux in ferromagnetic layers allows to reduce the local value of magnetic flux density felt by the superconductor. In this way, the critical current of the tape in low applied magnetic fields can be improved. This theoretical prediction is confirmed by experimental observation.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 605-608
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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