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Tytuł:
The Investigations of Chondritic Meteorites by X-ray Diffraction and Mössbauer Effect Methods
Autorzy:
Ludwig, A.
Zarek, W.
Popiel, E.
Powiązania:
https://bibliotekanauki.pl/articles/2028985.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.18.Fs
Opis:
The Mössbauer spectroscopy and X-ray diffraction techniques were used to investigate the mineral and magnetic fractions of two meteorites: carbonaceous chondrite named Allende (CV3) and ordinary chondrite - El Hammami (H5). The investigations of a powder mixture of chondrules and matrix show that the meteorites studied contain iron mainly in the silicates, olivine, and pyroxene. The metallic fractions of the El Hammami meteorite contain the ferromagnetic mineral kamacite (bcc iron-nickel alloy). This phase with cubic symmetry was identified by symmetric Mössbauer spectrum with disturbance in relative line intensities. The results suggest that the Allende meteorite does not contain a pure metallic phase.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 761-765
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Light Absorption and Photoluminescence in Quantum Dots and Artificial Molecules
Autorzy:
Firsov, D.
Vorobjev, L.
Panevin, V.
Fedosov, N.
Shalygin, V.
Samsonenko, J.
Tonkikh, A.
Cirlin, G.
Andreev, A.
Kryzhanovskaya, N.
Tarasov, I.
Pikhtin, N.
Ustinov, V.
Hanna, S.
Seilmeier, A.
Julien, F.
Zakharov, N.
Werner, P.
Powiązania:
https://bibliotekanauki.pl/articles/2041673.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
Opis:
Intraband absorption in n- and p-doped structures with InAs/GaAs quantum dots covered by InGaAs layers is studied both experimentally and theoretically. The absorption cross-section for p-type quantum dots was found to be significantly smaller than that for n-type quantum dots. Interband absorption bleaching under strong interband excitation is found and investigated in undoped quantum dot structures. Structures with artificial molecules were grown. Photoluminescence spectra and transmission electron microscopy images proves the presence of coupled symmetrical quantum dots.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 158-162
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Normal Incidence Mid-Infrared Photocurrent in AlGaN/GaN Quantum Well Infrared Photodetectors
Autorzy:
Sherliker, B.
Halsall, M. P.
Harrison, P.
Jovanović, V. D.
Indjin, D.
Ikonić, Z.
Parbrook, P. J.
Whitehead, M. A.
Wang, T.
Buckle, P. D.
Phillips, J.
Carder, D.
Powiązania:
https://bibliotekanauki.pl/articles/2041680.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
Opis:
We report the growth and characterization of AlGaN/GaN multiple quantum well structures designed to have intersubband transitions in the mid-infrared region of the spectrum. The samples were nominally undoped but were found to contain a high electron population in the wells induced by the local polarization fields. The sample was characterized by the use of the Raman spectroscopy and photocurrent spectroscopy. The Raman spectroscopy shows electronic Raman scattering from intersubband transitions in the AlGaN/GaN quantum wells. The e$\text{}_{1}$-e$\text{}_{2}$ and e$\text{}_{1}$-e$\text{}_{3}$ transitions of the confined 2d electron population in the wells can clearly be observed. A sample designed to absorb at 4μm was fabricated into mesa structures and the vertical photocurrent measured under normal incidence illumination from the free-electron laser FELIX. A wavelength and bias dependent photocurrent was observed in the mid-IR region of spectrum. The peak responsivity was of the order of 50μA/W at 4 K, the photocurrent still being measurable at room temperature.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 174-178
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Materials Surface Processing Spied by Hyperfine Interactions
Autorzy:
Schaaf, P.
Weisheit, M.
Krebs, H.-U.
Powiązania:
https://bibliotekanauki.pl/articles/2028943.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.18.Fs
Opis:
There are many aspects of materials surface processing ranging from simple heat treatments to ion implantation or laser surface treatments, e.g. the laser-plasma-coating formation in nitrogen gas, which is called laser nitriding. These methods are often very complicated, involving many basic processes and they have to be optimised for the desired application. Nuclear methods can be successfully applied for this task. First, Ag/Fe multilayers can be prepared by pulsed laser deposition employing an excimer laser. The Ag/Fe system is immiscible and sharp interfaces are expected for that reason. Nevertheless, it will be presented that some intermixing occurs which can be seen by conversion electron Mössbauer spectroscopy with the additional trick of preparing a sensitive $\text{}^{57}$Fe layer at various distances from the interfaces. Several Ag neighbours to the Fe spy-atom can be resolved, whose abundances vary with the location of the $\text{}^{57}$Fe marker layer. It is found that the intermixing at the bottom and top interface of the Fe layers is asymmetric.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 699-706
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hight-Field Submillimeter Magneto-Spectroscopy on Hg(Fe)Se
Autorzy:
Portugall, O.
Von Ortenberg, M.
Yokoi, H.
Takeyama, S.
Miura, N.
Van Bockstal, L.
Herlach, F.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1886979.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
Opis:
Magnetooptical phenomena in the zero-gap semimagnetic semiconductor Hg(Fe)Se are studied by various techniques in pulsed magnetic fields up to 150 T. Microscopical parameters are estimated in combination with results obtained from transport and magnetization measurements.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 363-367
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Obsidians
Autorzy:
Chojcan, J.
Sachanbiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933482.pdf
Data publikacji:
1995-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Fs
78.70.Bj
Opis:
Positron lifetime spectra as well as one-dimensional angular correlations of positron annihilation radiation were measured at room temperature for samples of rhyolitic obsidian coming from Iceland, Italy and Armenia. The samples were of different age. One specimen (originating from Iceland) was relatively young, formed in 1980. The others were much older, collected during the 19th century. It was found that the linear dimensions of pores trapping the positronium atoms before their decay as well as the pore concentration in all old obsidians are almost the same independently of the place of their formation. Simultaneously the concentration of the pores in the young sample is about five times lower than in the old specimens. Basing on the result it is suggested to extend the study in order to find out if positron annihilation can be used for the investigation of the age of the volcanic accumulations containing obsidian.
Źródło:
Acta Physica Polonica A; 1995, 88, 1; 103-110
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes of FIR Reflectivity of HgSe:Cr in a Magnetic Field
Autorzy:
Hausenblas, M.
Wyder, P.
Witowski, A. M.
Wittlin, A.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1921666.pdf
Data publikacji:
1992-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ls
78.30.Fs
Opis:
The results of FIR magnetoreflectivity of HgSe:Cr are presented. They are interpreted using a classical dynamic dielectric function.
Źródło:
Acta Physica Polonica A; 1992, 82, 5; 741-744
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Do the Mixed Crystals HgSeS Exhibit the One-Mode Behavior?
Autorzy:
Szuszkiewicz, W.
Witowski, A. M.
Julien, C.
Balkanski, M.
Dybko, K.
Witkowska, B.
Mycielski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1924226.pdf
Data publikacji:
1992-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ls
78.30.Fs
Opis:
The low-temperature far-infrared reflectivity spectra of HgSe and HgSeS are measured and analysed. The results suggest the one-mode behavior of phonon excitations in HgSeS mixed crystals.
Źródło:
Acta Physica Polonica A; 1992, 82, 5; 887-889
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Tektite and Hyalite
Autorzy:
Chojcan, J.
Sachanbiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1928968.pdf
Data publikacji:
1993-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Fs
78.70.Bj
Opis:
Positron lifetime spectra as well as one-dimensional angular distributions of photons coming from the two-photon annihilation of an electron-positron pair were measured at room temperature for samples of natural tektite and hyalite. The data were used for estimation of positronium characteristics in the specimens. The characteristics were analysed in terms of parameters of pores trapping the positronium atoms before their decay. In the analysis two models of the traps were taken into account, i.e. the square potential wells of spherical symmetry with barriers of finite and infinite heights. It was found that the linear dimensions of the pores resulting from these two-trap models are almost the same and they are of the order of 1 nm.
Źródło:
Acta Physica Polonica A; 1993, 83, 3; 267-271
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Frequency Raman Spectrum οf Bulk $Zn_{0.984}Co_{0.016}O$ Crystal
Autorzy:
Szuszkiewicz, W.
Łusakowski, A.
Morhange, J.
Gołacki, Z.
Arciszewska, M.
Brodowska, B.
Kanehisa, M.
Klepka, M.
Dobrowolski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1807848.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.30.Fs
Opis:
The influence of possible presence of $Co^{2+}$ ion pairs in a bulk $Zn_{1-x}Co_{x}O$ mixed crystal on the low-frequency part of the Raman spectrum is discussed. Two effects can be taken into account in the theoretical considerations when analyzing the energy level scheme corresponding to Co ions. The first is a local lattice deformation in the vicinity of $Co^{2+}$ ion due to a presence of the second ion, smaller than the host ZnO lattice cation. Such deformation creates a trigonal field, which can only slightly modify the energy levels of $Co^{2+}$ ion. The second effect, which results from an antiferromagnetic superexchange interaction between two $Co^{2+}$ ions is responsible for a new set of energy levels. The Raman data taken at low temperature on the sample corresponding to the composition x = 0.016 demonstrated the presence of two structures at about 6 $cm^{-1}$ and 13 $cm^{-1}$. These structures may be interpreted as electronic transitions between the ground state and the first excited state of a single $Co^{2+}$ ion in the substitution site of ZnO lattice and as a similar transition for $Co^{2+}$ ion pair, respectively.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 103-106
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Far-Infrared Magneto-Optical Studies of HgTe-CdTe Superlattices in the Semimetallic Regime
Autorzy:
Wojtowicz, T.
Dobrowolska, M.
Furdyna, J.K.
Meyer, J. R.
Bartoli, F. J.
Hoffman, C. A.
Ram-Mohan, L. R.
Powiązania:
https://bibliotekanauki.pl/articles/1888086.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.65.Fa
78.30.Fs
Opis:
We review recent magneto-optical investigations performed on HgTe-CdTe semimetallic superlattices. Far infrared magnetotransmission data obtained as a function of temperature, photon energy, and sense of circular polarization are compared with the predictions of a comprehensive new theory which fully incorporates the complexities of type-III superlattice band structure. It is found that the theory accounts for nearly all of the many unusual features which have been observed experimentally. These include the occurrence of two cyclotron resonances due to holes; the coexistence of electron and hole cyclotron resonances in the low temperature limit; the observation of three distinct CRA minima; a step-like change in the temperature dependence of the electron cyclotron mass; and a dramatic increase of the CRI absorption peak intensity with increasing magnetic field.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 245-254
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Scattering Dynamics of Free Excitons on Fe$\text{}^{++}$ Ions in Cd$\text{}_{1-x}$Fe$\text{}_{x}$Se
Autorzy:
Gaj, J. A.
Nguyen, The Khoi
Nawrocki, M.
Golnik, A.
Lebecki, K.
Powiązania:
https://bibliotekanauki.pl/articles/1891231.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.30.Fs
Opis:
Inelastic scattering of excitons on Fe$\text{}^{++}$ ions in Cd$\text{}_{1-x}$Fe$\text{}_{x}$Se was studied by resonant Raman scattering. Polarization measurements were done using a modulation technique, allowing for the first time to determine the full polarization state of the detected light. The obtained results were compared to a simple calculation in an incoherent model of scattering on Fe$\text{}^{++}$ ions.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 409-412
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Studies of Defects in Graphene Grown on SiC
Autorzy:
Grodecki, K.
Bożek, R.
Borysiuk, J.
Strupinski, W.
Wysmolek, A.
Stępniewski, R.
Baranowski, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/2047919.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.48.Gh
78.30.Fs
Opis:
The Raman scattering studies of multi-layer graphene obtained by high temperature annealing of carbon terminated face of 4H-SiC(000-1) substrates are presented. Intensity ratio of the D and G bands was used to estimate the average size of the graphene flakes constituting carbon structures. The obtained estimates were compared with flake sizes from atomic force microscopy data. We found that even the smallest structures observed by atomic force microscopy images are much bigger than the estimates obtained from the Raman scattering data. The obtained results are discussed in terms of different average flake sizes inside and on the surface of the multi-layer graphene structure, as well as different type of defects which would be present in the investigated structures apart from edge defects.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 595-596
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of Pb$\text{}_{1-x}$Cd$\text{}_{x}$Te Solid Solution Structure at High Temperatures
Autorzy:
Minikayev, R.
Dynowska, E.
Kamińska, E.
Szczerbakow, A.
Trots, D.
Story, T.
Szuszkiewicz, W.
Powiązania:
https://bibliotekanauki.pl/articles/2048121.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
81.10.Fq
Opis:
The recent successful growth of single, bulk Pb$\text{}_{1-x}$Cd$\text{}_{x}$Te crystals by self-selecting vapor transport method at the Institute of Physics of the Polish Academy of Sciences in Warsaw opened new opportunities to study the physical properties of this interesting material in detail. In this work we report the preliminary results of X-ray powder diffraction studies performed on a set of Pb$\text{}_{1-x}$Cd$\text{}_{x}$Te solid solutions (where x ≤ 0.056) at high temperatures (295 K ≤ T ≤ 1100 K) and analyzed with the Rietveld refinement. Our results demonstrate the necessity of some correction of the relevant phase diagram and of the solubility limit, known from the literature.
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 699-701
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coupling of Infrared Radiation to Intersubband Transitions in Tunneling Superlattices
Autorzy:
Nalewajko, C.
Załużny, M.
Powiązania:
https://bibliotekanauki.pl/articles/1991960.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.30.Fs
73.20.Dx
Opis:
The influence of the interference effects on the intersubband absorption line shape in weakly tunneling superlattices is discussed within the framework of nonlocal effective medium approximation.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 446-448
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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