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Wyświetlanie 1-12 z 12
Tytuł:
Influence of Magnetic Field on Blue Anti-Stokes Luminescence of ZnSe:Cr Crystals
Autorzy:
Ivanov, V. Yu.
Semenov, Yu.G.
Surma, M.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1950807.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
78.55.Et
76.30.Fc
Opis:
The results of photoluminescence and magneto-luminescence studies of chromium doped ZnSe crystals are presented for blue colour shallow donor-shallow acceptor pair photoluminescence, with a zero phonon line at 2.692 eV. This donor-acceptor pair photoluminescence is observed under photo-excitation with photon energies smaller than the emission energy (anti-Stokes luminescence) and dominates in the photoluminescence spectrum of ZnSe:Cr at the excitation energy about 2.41 eV and for temperature T<20 K. A quantum efficiency of this anti-Stokes luminescence is relatively large. It is of about 10$\text{}^{-3}$ at 0 T and increases with increasing magnetic field up to 7 T at temperature T=2 K. We relate the intensity of the anti-Stokes luminescence to a non-equilibrium concentration of photo-excited Cr$\text{}^{+}$ ions and propose that the rate of spin-dependent recombination of Cr$\text{}^{+}$ ions with free holes (decreases with increasing magnetic field) is responsible for the observed increase in the anti-Stokes luminescence intensity at higher magnetic fields.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 821-824
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nature of Blue Anti-Stokes Luminescence in ZnSe:Cr
Autorzy:
Ivanov, V. Yu.
Semenov, Yu. G.
Surma, M.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933759.pdf
Data publikacji:
1995-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
71.55.Gs
78.55.Et
Opis:
The mechanism of the anti-Stokes photoluminescence in ZnSe:Cr is discussed. It is shown that the two-step ionization transitions of Cr(2$\text{}^{+}$ ↔ 1$\text{}^{+}$) result in appearance of the blue anti-Stokes photoluminescence of ZnSe:Cr. There are also some indications that the Auger type co-operative process can contribute to the photoluminescence excitation.
Źródło:
Acta Physica Polonica A; 1995, 88, 4; 743-746
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Microscopic Mechanisms of Blue Anti-Stokes Luminescence in Undoped and Chromium Doped ZnSe Crystals
Autorzy:
Ivanov, V. Yu.
Omel'chuk, A.
Godlewski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1991537.pdf
Data publikacji:
1998-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
78.55.Et
76.30.Fc
Opis:
Anti-Stokes luminescence is observed in chromium doped and in undoped ZnSe crystals. In the former case anti-Stokes luminescence is due to two complementary ionization transitions of Cr ions. In the latter case two-photon absorption becomes important at a high excitation density.
Źródło:
Acta Physica Polonica A; 1998, 94, 3; 365-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Electronic Properties of Sr$\text{}_{1-x}$A$\text{}_{x}$CuO$\text{}_{2+δ}$ where A=La, K, and Ca
Autorzy:
Onyszkiewicz, I.
Czarnecki, P.
Poltoracky, Yu. B.
Zimpel, M.
Powiązania:
https://bibliotekanauki.pl/articles/1929860.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
72.15.-v
76.30.Fc
Opis:
The electronic properties of Sr$\text{}_{1-x}$A$\text{}_{x}$CuO$\text{}_{2+δ}$ (A = La, K, Ca) were examined. The crystal structure of the synthesized compounds was identified as orthorhombic with some admixture of tetragonal phase. For Sr$\text{}_{1-x}$La$\text{}_{x}$CuO$\text{}_{2+δ}$ the insulator-metal like transition was observed with increasing La content. The d$\text{}_{x²-y²}$ ground state of Cu ions was deduced from electron spin resonance measurements. The electronic state of Cu ions and their surrounding local symmetry was also found to be La and oxygen content dependent.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 303-306
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanism of Radiative Mn$\text{}^{2+}$ Intra-Shell Recombination in Bulk ZnMnS
Autorzy:
Ivanov, V. Yu.
Godlewski, M.
Yatsunenko, S.
Khachapuridze, A.
Li, M. S.
Gołacki, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2027501.pdf
Data publikacji:
2001-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
76.70.Hb
78.55.Et
Opis:
Origin of a fast component of the photoluminescence decay of Mn$\text{}^{2+}$ intra-shell $\text{}^{4}$T$\text{}_{1}$ → $\text{}^{6}$A$\text{}_{1}$ transition is discussed based on the results of photoluminescence, photoluminescence kinetics and optically detected magnetic resonance experiments performed for bulk ZnMnS samples with about 1% Mn fraction. It is demonstrated that a fast component of the photoluminescence decay, reported previously for quantum dot structure and related to quantum confinement effects, is also observed in bulk samples and is related by us to very efficient spin cross-relaxation effects.
Źródło:
Acta Physica Polonica A; 2001, 100, 3; 351-355
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intramolecular and Lattice Dynamics in V$\text{}_{6-n}^{IV}$V$\text{}_{n}\text{}^{V}$ O$\text{}_{7}$(OCH$\text{}_{3}$)$\text{}_{12}$ Crystal
Autorzy:
Yablokov, Yu. V.
Augustyniak-Jabłokow, M. A.
Borshch, S.
Daniel, C.
Hartl, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043556.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
36.40.Cg
Opis:
Multi-nuclear mixed-valence clusters V$\text{}_{4}^{IV}$V$\text{}_{2}^{V}$O$\text{}_{7}$(OCH$\text{}_{3}$)$\text{}_{12}$ were studied by X-band EPR in the temperature range 4.2-300 K. An isotropic exchange interactions between four V$\text{}^{IV}$ ions with individual spin S$\text{}_{i}$=1/2 determine the energy levels structure of the compound with the total spin states S=0, 1, and 2, which are doubled and split due to the extra electron transfer. The spin-Hamiltonian approach was used for the analysis of the temperature dependences of the EPR spectra parameters and the cluster dynamics. Two types of the electron transfer are assumed: the single jump transfer leading to the splitting of the total spin states by intervals comparable in magnitude with the exchange parameter J≈100-150 cm$\text{}^{-1}$ and the double jump one resulting in dynamics. The dependence of the transition ratesν$\text{}_{tr}$ on the energy of the total spin states was observed. In particular, in the range 300-220 K theν$\text{}_{tr}$ ≈0.7×10$\text{}^{10}$ cm$\text{}^{-1}$ and below 180 K the ν$\text{}_{tr}$≈1×10$\text{}^{10}$ cm$\text{}^{-1}$ was estimated. The g-factors of the spin states were shown to depend on the values of the intermediate spins. A phase transition in the T-range 210-180 K leading to the change in the initial V$\text{}^{IV}$ ions localization was discovered.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 271-281
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin of Ultrafast Component of Photoluminescence Decay in Nanostructures Doped with Transition Metal or Rare-Earth Ions
Autorzy:
Godlewski, M.
Yatsunenko, S.
Ivanov, V. Yu.
Khachapuridze, A.
Świątek, K.
Goldys, E. M.
Phillips, M. R.
Klar, P. J.
Heimbrodt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2041630.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
76.70.Hb
78.55.Et
Opis:
Bulk samples, layers, quantum well, and quantum dot structures of II-Mn-VI samples all show coexistence of slow and fast components of Mn$\text{}^{2+}$ photoluminescence decay. Thus, fast photoluminescence decay cannot be related to low dimensionality of a host material. This also means that the model of the so-called quantum confined atom is incorrect. Based on the results of time-resolved photoluminescence and optically detected magnetic resonance investigations we relate the observed lifetime decrease in Mn$\text{}^{2+}$ intra-shell transition to spin dependent magnetic interactions between localized spins of Mn$\text{}^{2+}$ ions and between Mn$\text{}^{2+}$ ions and spins/magnetic moments of free carriers. The latter mechanism is enhanced in nanostructures.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 65-74
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Origin of EPR Signals in SrCuO$\text{}_{2}$ Ceramics
Autorzy:
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Ivanova, T. A.
Jacyna-Onyszkiewicz, I.
Shustov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/2043623.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
76.30.Fc
81.05.Je
Opis:
The origin and thermal evolution of the EPR signals in SrCuO$\text{}_{2}$ ceramics are studied. It has been shown that the EPR signals observed in this ceramic material are due to contamination with other phases. The axial signal is due to SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O, which is a product of water reactions with SrCuO$\text{}_{2}$.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 345-351
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Water Induced Decomposition of the SrCuO$\text{}_{2}$ and Sr$\text{}_{2}$CuO$\text{}_{3}$ Ceramics Surface. The Role of Carbon Dioxide
Autorzy:
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Jacyna-Onyszkiewicz, I.
Ivanova, T. A.
Shustov, V. A.
Powiązania:
https://bibliotekanauki.pl/articles/2047737.pdf
Data publikacji:
2007-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ee
76.30.Fc
81.05.Je
Opis:
Processes of SrCuO$\text{}_{2}$ and Sr$\text{}_{2}$CuO$\text{}_{3}$ ceramics decomposition induced by contact with water and carbon dioxide were studied by EPR. The dominant signals in the spectra were found to originate from Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$ (for Sr$\text{}_{2}$CuO$\text{}_{3}$) and SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O (for SrCuO$\text{}_{2}$) compounds. The thermally induced conversion of SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O into Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$ was analysed, and its product CuO was found to exist in the nanocrystalline form. The presence of CO$\text{}_{2}$, reacting with Sr(OH)$\text{}_{2}$, was shown to modify the decomposition process leading to the appearance of SrCu(OH)$\text{}_{4}$·H$\text{}_{2}$O, some hydroxycarbonates and Cu(OH)$\text{}_{2}$ on the surface of ceramics studied. At temperatures higher than 300ºC CuO reacts back with Sr(OH)$\text{}_{2}$. For the samples being in contact with atmospheric moisture this compound, deposited on a surface of SrCuO$\text{}_{2}$, decomposes to Sr$\text{}_{2}$Cu(OH)$\text{}_{6}$. The presence of the antiferromagnetic compounds Cu(OH)$\text{}_{2}$, CuO, and Cu$\text{}_{2}$[(OH)$\text{}_{2}$CO$\text{}_{3}$] in the samples can influence the results of magnetic measurements of the studied ceramics.
Źródło:
Acta Physica Polonica A; 2007, 112, 3; 525-536
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of Auger-Type Energy Transfer Processes in Quenching of Anti-Stokes Emission in Chromium and Iron Doped ZnSe: ODMR, Optical and Time-Resolved Study
Autorzy:
Ivanov, V. Yu.
Karczewski, G.
Godlewski, M.
Omel'chuk, A. R.
Belyaev, A. E.
Zhavoronkov, N. V.
Powiązania:
https://bibliotekanauki.pl/articles/2036871.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
78.55.Et
76.30.Fc
Opis:
Energy up-conversion in chromium and iron doped ZnSe results in the appearance of an anti-Stokes luminescence. The process is efficient in ZnSe:Cr, but not in ZnSe:Fe. We conclude that very efficient three-center Auger processes in ZnSe:Fe quench the anti-Stokes luminescence emission. For chromium doped samples influence of the Auger mechanism is weaker, which we explain by less efficient carrier retrapping by Cr ions. We further discuss possibility of efficient pumping of infrared Cr-related emissions via Cr photoionization transition.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 695-701
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Discovery of a New Pressure-Induced Low-Spin Phase in (2Me-5Et-PyH)[Fe(Th-5Cl-Sa)$\text{}_{2}$]
Autorzy:
Krupska, A.
Augustyniak-Jabłokow, M. A.
Yablokov, Yu. V.
Zelentsov, V. V.
Ulanov, V. A.
Mroziński, J.
Powiązania:
https://bibliotekanauki.pl/articles/2046891.pdf
Data publikacji:
2006-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.Fc
75.30.Wx
Opis:
Electron paramagnetic resonance studies of the high-spin (HS) ↔ low-spin (LS) transition in 2-methyl-5-ethyl-pyridine-5-chloro-salicylalt hiosemicarbazonatoferrate(III) performed under hydrostatic pressure up to 500 MPa in a temperature range of 80-310 K have revealed two modifications of the low spin complexes: low-pressure (LS1) and high-pressure (LS2) ones. Under atmospheric pressure LS1 appears on cooling and disappears on heating at 220 K. The hydrostatic pressure shifts the transition to higher temperatures. Below 275 K an increase in pressure to 410 MPa results in abrupt changes in the g-factor and widthΔ B of the EPR line indicating a transition to a new phase. The pressure-induced transition LS1 ↔ LS2 is almost independent of T up to 275 K, where at a pressure of 420 MPa a triple point is observed. The LS1↔ LS2 and HS↔ LS2 (at T>260 K) transitions occur with a large hysteresis of about 95 MPa. The process of the spin transition has been shown to begin with the formation of domains of LS complexes in the matrix of HS ones. The response of the domains to external factors has been studied.
Źródło:
Acta Physica Polonica A; 2006, 110, 1; 81-95
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Dependent Interactions of Free Carriers and Manganese Ions in Nanostructures of Wide Band Gap II-Mn-VI Semiconductors - Mechanism of Lifetime Reduction
Autorzy:
Yatsunenko, S.
Khachapuridze, A.
Ivanov, V. Yu.
Godlewski, M.
Khoi, Le Van
Gołacki, Z.
Karczewski, G.
Goldys, E. M.
Phillips, M.
Klar, P. J.
Heimbrodt, W.
Powiązania:
https://bibliotekanauki.pl/articles/2036034.pdf
Data publikacji:
2003-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Gs
76.30.Fc
76.70.Hb
78.55.Et
Opis:
Based on the results of optically detected magnetic resonance and time-resolved investigations we relate the observed lifetime shortening of intra-shell Mn$\text{}^{2+}$ emission to spin dependent magnetic interactions between localized spins of Mn$\text{}^{2+}$ ions and spins/magnetic moments of free carriers. We show that this mechanism is active in both bulk and in low dimensional structures, such as quantum wells, quantum dots, and nanostructures.
Źródło:
Acta Physica Polonica A; 2003, 103, 6; 643-648
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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