Temat: 78.20.Ci - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Free Exciton Luminescence in ZnCdSe Solid Solutions, ZnSe Epitaxial Films and ZnSe$\text{}_{1-x}$S$\text{}_{x}$/ZnSe$\text{}_{1-y}$S$\text{}_{y}$ Superlattices
Autorzy:: Tenishev, L. N.
Permogorov, S. A.
Fedorov, D. L.
Yakushcheva, G. G.
Kuznetsov, P. I
Tematy:: 78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1952205.pdf Link otwiera się w nowym oknie
Opis:: We studied the luminescence of bulk Zn$\text{}_{1-x}$Cd$\text{}_{x}$Se solid solutions, epitaxial ZnSe films and ZnSe$\text{}_{1-x}$S$\text{}_{x}$/ZnSe$\text{}_{1-y}$S$\text{}_{y}$ superlattices at T=2-80 K. The analysis of the bands of exciton radiative annihilation with simultaneous emission of 1 or 2 LO phonons shows that the excitons in the studied samples can be considered as free particles with thermalized distribution of kinetic energies. In ZnSe$\text{}_{1-x}$S$\text{}_{x}$/ZnSe$\text{}_{1-y}$S$\text{}_{y}$ superlattices a three-dimensional character of exciton motion was established. The periodic potential of superlattice perturbs the exciton wave vector and induces additional elastic scattering of excitons.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Liquid Nitrogen and Room Temperature Reflectivity Spectra of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Se in the 0.5-6.0 eV Energy Range
Autorzy:: Dębowska, D.
Zimnal-Starnawska, M.
Kisiel, A.
Giriat, W.
Tematy:: 78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931834.pdf Link otwiera się w nowym oknie
Opis:: The reflectivity measurements for mixed crystals Cd$\text{}_{1-x}$Fe$\text{}_{x}$Se (0.00 ≤ x ≤ 0.10) have been carried out in an energy range of 0.5-6.0 eV at 300 and 77 K. The influence of Fe$\text{}^{2+}$(3d$\text{}^{6}$) states on the changes in the energy positions of the reflectivity maxima E$\text{}_{0}$, E$\text{}_{1}$(A$\text{}_{1}$), E$\text{}_{1}$(A$\text{}_{2}$), and E$\text{}_{1}$(B) is analyzed and the obtained results are consistent with the models existing in the literature.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Excitonic Spectra of Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te Crystals
Autorzy:: Permogorov, S. A.
Tenishev, L. N.
Surkova, T. P.
Tematy:: 78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1921609.pdf Link otwiera się w nowym oknie
Opis:: Strong modification of the optical spectra near the band-gap edge is observed in Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te crystals as compared to the spectra of a pure compound. The evolution of the luminescence spectra at the increase in Fe concentration is represented by the change of radiative recombination channels from dominantly (A$\text{}^{0}$, x) acceptor bound exciton emission in undoped CdTe to the free exciton luminescence in Cd$\text{}_{1-x}$Fe$\text{}_{x}$Te solid solutions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Reflectivity Study of the Zn$\text{}_{1-x}$Co$\text{}_{x}$Se Crystals
Autorzy:: Kowalski, B. J.
Gołacki, Z.
Orłowski, B. A.
Tematy:: 78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1890987.pdf Link otwiera się w nowym oknie
Opis:: The room temperature reflectivity spectra of the Zn$\text{}_{1-x}$Co$\text{}_{x}$Se (x = 0, 0.03, 0.05) crystals have been measured in the visible and ultraviolet range from 1.7 to 12 eV. The structure of the spectra was interpreted in terms of the electronic band structure of the binary material (ŻnSe). The experimental results were compared with the reflectivity spectra of the Fe-based semi magnetic semiconductors [1], and the interpretation was confronted with the conclusions derived from the photoemission experiments performed for Cd$\text{}_{1-x}$Co$\text{}_{x}$Se [2] and the tight-binding CPA calculations of the band structure of Zn$\text{}_{1-x}$Co$\text{}_{x}$Se [3].
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Determination of Some Heavyweight Aggregate Half Value Layer Thickness Used for Radiation Shielding
Autorzy:: Akkurt, İ.
Başyiğit, C.
Akkaş, A.
Kılınçarslan, Ş.
Mavi, B.
Günoğlu, K.
Tematy:: 78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1490934.pdf Link otwiera się w nowym oknie
Opis:: A radiation dose above the maximum permissible limit is very dangerous for human being. In radiation shielding, absorbent materials' properties must be well known. Heavyweight concrete is the most widely used in the world for this aim. The aggregate component of concrete plays an important role in improving concrete properties and this is effect of shielding properties of concrete. The thickness of any given material where 50% of the incident energy has been attenuated is known as the half-value layer. The half-value layer is expressed in units of distance (mm or cm). Like the attenuation coefficient, it is photon energy dependent. Increase of the penetrating energy of a stream of photons will result in an increase in a material's half-value layer. In this study, half-value layer thickness of concrete containing limonite, siderite and barite at different ratios was investigated; for this purpose measurements have been obtained by a collimated beam of gamma ray from sources $\text{}^{60}Co$. The total linear attenuation coefficient (μ), half-value layer thickness is evaluated in this study.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Reflectivity Study of HgSe$\text{}_{1-x}$Te$\text{}_{x}$ Crystals
Autorzy:: Kowalski, B. J.
Dybko, K.
Lemańska, A.
Orłowski, B. A.
Tematy:: 78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1923860.pdf Link otwiera się w nowym oknie
Opis:: The room temperature reflectivity spectra of HgSe$\text{}_{1-x}$Te$\text{}_{x}$ (x = 0, 0.4, 0.5, 1.0) crystals were measured in the visible and ultraviolet range from 1.5 to 12 eV. The maxima characteristic of the binary HgA$\text{}^{IV}$ compounds can be revealed in the mixed crystals spectra, but their position depends on the crystal composition. There is no duplication of the spectral features in spite of the different energy position of the maxima for HgSe and HgTe. This suggests that the virtual crystal approximation could be used to describe basic optical properties of HgSe$\text{}_{1-x}$Te$\text{}_{x}$.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Saturation Processes in Nonlinear Media Modeled by Four-Level Configuration with Coincident Absorption and Emission Bands
Autorzy:: Addasi, J.
Tematy:: 78.20.Bh
78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1419788.pdf Link otwiera się w nowym oknie
Opis:: The four-level model is used to study the nonlinear media with coincident absorption and emission bands in both principal $(S_0-S_1)$ and excited $(T_1-T_2)$ channels. The excitation of molecules occurred by two light fields: radiations with intensity $I_{12}$ at frequency $\omega_0$ tuned at the centre of absorption band of principal singlet-singlet channel and radiations with intensity $I_{34}$ at frequency ω tuned at the centre of absorption band of excited triplet-triplet channel. The monotonic dependence of phase response of media in both principal and excited channels and the saturation processes are studied theoretically and numerically for four-level model.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Dielectric Permeability of Nanocylinder
Autorzy:: Jaćimovski, S.
Sajfert, V.
Raković, D.
Tošić, B.
Tematy:: 78.20.Ci
78.40.Me; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1537830.pdf Link otwiera się w nowym oknie
Opis:: In the nanocylinder, a cut-off from the molecular crystal, dielectric permeability tensor is investigated. Excitons in the nanocylinder arise due to the exciting of the electron subsystem of the molecule. In evaluation of dielectric permeability Dzhyaloshinskii-Pitaevskii approach is used, connected with retarded and advanced exciton Green's functions and correct use of Paulion Green's function. It turned out that refraction and absorption indices depend on configuration coordinates, having maximal values at boundary cross-sections and minimal value at central cross-section of the nanocylinder broken symmetry structure. Although it was expected that boundary conditions make higher refractive and absorptive characteristics of the nanocylinder, this appeared not to be possible because Paulion Green's function is not proportional to the exciton concentration.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Linear Dichroism Spectra of Doped Calcium Gallogermanate Crystals
Autorzy:: Shopa, Y.
Ftomyn, N.
Tematy:: 78.20.Ci
78.20.Fm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1550185.pdf Link otwiera się w nowym oknie
Opis:: Polarized absorption and linear dichroism spectra of chromium and manganese doped gallogermanate $(Ca_{3}Ga_{2}Ge_{4}O_{14})$ crystals were measured and analyzed. Electronic transitions were identified and crystal field parameters have been determined. The value of linear dichroism obtained at the wavelength of 633 nm was compared with polarimetric measuring data for chromium doped $Ca_{3}Ga_{2}Ge_{4}O_{14}$ crystals.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Ellipsometric Studies of NdMnO$\text{}_{3}$ Single Crystals
Autorzy:: Babonas, G. J.
Reza, A.
Szymczak, R.
Baran, M.
Shiryaev, S.
Fink-Finowicki, J.
Szymczak, H.
Tematy:: 71.20.-b
78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2037130.pdf Link otwiera się w nowym oknie
Opis:: Ellipsometric studies of NdMnO$\text{}_{3}$ single crystals of orthorhombic symmetry were carried out in the spectral range 0.5-5.0 eV. Experimental data, which were obtained on the (001)$\text{}_{pc}$-type planes of pseudo-cubic system, were analyzed in the model of biaxial crystal. For the first time, three componentsε$\text{}_{x}$,ε$\text{}_{y}$,ε$\text{}_{z}$ of the effective dielectric function for manganites of orthorhombic symmetry were determined. From ellipsometric data, the spectra of optical conductivity and loss function were also calculated and considered. The fine structure of the spectra and optical anisotropy was the basis for discussion of the microscopic origin of the optical transitions responsible for the optical features. The electronic excitations due to dipole-forbidden spin-allowed transitions of the d-d-type in Mn-ions, f-f-type in Nd-ions and charge-transfer 2p(O)-3d(Mn) transitions were taken into account. The data for NdMnO$\text{}_{3}$ were compared with those obtained for other related undoped and doped single crystals of perovskite-type structure, LaMnO$\text{}_{3}$, (LaBa)(MnCo)O$\text{}_{3}$ and (LaCa)CoO$\text{}_{3}$.
Dostawca treści:: Biblioteka Nauki

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