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Wyświetlanie 1-11 z 11
Tytuł:
Gd$\text{}^{3+}$ Spin-Phonon Interactions in Rare-Earth Fluoride Crystals
Autorzy:
Paradowski, M. L.
Misiak, L. E.
Powiązania:
https://bibliotekanauki.pl/articles/2035540.pdf
Data publikacji:
2002-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
76.30.Kg
Opis:
The X-band EPR study of Gd$\text{}^{3+}$-doped LaF$\text{}_{3}$, La$\text{}_{0.9}$Ce$\text{}_{0.1}$F$\text{}_{3}$, La$\text{}_{0.9}$Nd$\text{}_{0.1}$F$\text{}_{ }$3, LiYF$\text{}_{4}$ and LiY$\text{}_{0.9}$Yb$\text{}_{0.1}$F$\text{}_{4}$ single crystals in the temperature range 4.2-295 K was carried out in order to investigate the Gd$\text{}^{3+}$ spin-phonon interactions. Spin-Hamiltonian parameters are analysed in the light of the superposition model and the rotational invariance theory for phonon-induced contributions to spin-Hamiltonian parameters. The 4f$\text{}^{7}$ electron-phonon interactions can be described by the Debye model. It is suggested, from the rotational invariance mechanism for phonon-induced contributions to spin-Hamiltonian parameters, that the rotational contributions are much smaller than those from the strain. Temperature-induced distortions of the crystal field, as well as these distortions caused by the La$\text{}^{3+}$/Nd$\text{}^{3+}$ and Y$\text{}^{3+}$/Yb$\text{}^{3+}$ substitutions, influence significantly the 4f$\text{}^{7}$ electron-phonon interactions. The coupling constant K$\text{}_{2}$ of 4f$\text{}^{7}$ electrons to the whole phonon spectrum of the crystal lattice is stronger in the LaF$\text{}_{3}$, La$\text{}_{0.9}$Ce$\text{}_{0.1}$F$\text{}_{3}$, La$\text{}_{0.9}$Nd$\text{}_{0.1}$F$\text{}_{3}$ with larger temperature-induced distortion of the Gd$\text{}^{3+}$ site symmetry than in LiYF$\text{}_{4}$, LiY$\text{}_{0.9}$Yb$\text{}_{0.1}$F$\text{}_{4}$. Our results are compared with those for Gd$\text{}^{3+}$-doped RbCdF$\text{}_{3}$ and PbF$\text{}_{2}$ single crystals.
Źródło:
Acta Physica Polonica A; 2002, 102, 3; 373-384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fluoride Levels in the Eastern Black Sea Basin Streams, Turkey
Autorzy:
Bayram, A.
Satilmiş, U.
Nas, S.
Kemer, B.
Powiązania:
https://bibliotekanauki.pl/articles/1031272.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
92.40.Qk
92.40.qf
Opis:
The aim of this study is to monitor the fluoride ion (F¯), as well as chloride ion (Cl¯), variation in the Eastern Black Sea Basin streams, and to evaluate drinking water quality of these streams, with reference to national and international directives and guidelines. The water samples (240) were semimonthly collected from three surface water resources, namely from the Değirmendere and Galyan streams in Trabzon Province, the biggest city on the Southeastern Black Sea Coast with a total population of 768 417, and the Harşit Stream in Gümüşhane and Giresun provinces. The monitoring results have revealed that the average F¯ concentration had varied between 0.154 and 0.200 mg/l in the Değirmendere Stream and between 0.156 and 0.163 mg/l in the Galyan Stream, respectively. However, the treated stream waters had lower F¯ concentrations, varying between 0.010 and 0.080 mg/l, than the untreated stream waters. In the Harşit Stream, the average F¯ concentrations were at relatively higher values, which ranged from 0.211 to 0.296 mg/l, in the uppermost stations, however showed a steadily decreasing trend throughout the lowermost stations and fell from 0.230 to 0.141 mg/l due to the hydropower dam reservoirs, namely Torul, Kürtün, and Akköy, operated in the watershed. The average Cl¯ concentrations have varied between 2.00 and 6.48 mg/l. On the one hand, the waters from the Değirmendere, Galyan, and Harşit streams are classified as high quality, considering the upper threshold values of 1.5 mg F¯/l and 250 mg Cl¯/l. On the other hand, these streams can be regarded as the fluoride-poor water resources.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 861-865
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Point Defects in Magnesium Aluminates Spinel Ceramics Doped with Lithium Fluoride
Autorzy:
Gritsyna, V.
Kazarinov, Yu.
Moskvitin, A.
Reimanis, I.
Powiązania:
https://bibliotekanauki.pl/articles/1550494.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
61.72.J-
Opis:
The nature and topological distribution of optical centers within various regions of hot pressed disks of transparent magnesium aluminates spinel ceramics doped with LiF were studied. In the optical absorption spectra of this type of ceramic, bands were revealed at 4.75 eV and 5.3 eV, which were identified with $F^{+}-$ and F-centers, respectively. Because both bands are formed by anionic vacancies which captured one or two electrons, the topological distribution of anionic vacancies was determined. The band at 5.65 eV was also found which is tentatively identified with complex centers of anionic vacancies that capture fluorine ions and electrons. Using X-ray irradiation the variety of absorption bands of hole centers related to cationic vacancies was established. The spatial distribution of cationic vacancies within the ceramic disk was also determined.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 161-165
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Short Review on Fluoride Laser Crystals Grown by Czochralski Method at IPEN
Autorzy:
Baldochi, S.
Ranieri, I.
Powiązania:
https://bibliotekanauki.pl/articles/1399462.pdf
Data publikacji:
2013-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Fq
42.70.-a
42.70.Hj
Opis:
In this article there are presented the developments on the crystal growth by the Czochralski method of fluoride laser materials at the Center for Lasers and Applications from Institute of Nuclear and Energy Research, IPEN, Brazil. A brief report of the Czochralski furnace preparation for fluorides growth regarding to its construction materials, influence of the heating assemblies in the thermal profiles and the benefits of using a suitable atmosphere is provided. Moreover, to demonstrate the importance of this technique to the advances on laser systems over the last years there are described the specific growth conditions established to obtain fluoride crystals with suitable properties for practical application as laser hosts. $LiREF_4$ (RE = rare earth) scheelite crystals have been studied to compare $LiYF_4$ (YLF) with its isomorphs, including solid solutions of the type-$LiY_{1-x}Ln_{x}F_4$ (Ln = Gd or Lu) and $LiGd_{1-x}Lu_{x}F_4$, relating to their optical quality, spectroscopic and laser properties. Some results regarding the development of new laser hosts of these materials doped with Nd, Er, Pr and co-doped Yb, Nd and Tm are also presented. The growth particularities of transition metals doped fluoride crystals such as $BaLiF_3$:TM (TM = Ni and Co) and $LiSrAlF_6$:Cr are also reported.
Źródło:
Acta Physica Polonica A; 2013, 124, 2; 286-294
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calcium Fluoride Barrier Layer in Tunnel Emitter Phototransistor
Autorzy:
Illarionov, Y.
Vexler, M.
Suturin, S.
Fedorov, V.
Sokolov, N.
Powiązania:
https://bibliotekanauki.pl/articles/1490944.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Qv
73.40.Gk
73.61.Ng
Opis:
Owing to the optimized growth technology of the 1-2 nm calcium fluoride films on n-(111)-silicon, metal/tunnel-insulator/semiconductor phototransistors have been fabricated by the molecular beam epitaxy at the temperature 250°C. The characteristics of these transistors were measured in a wide range of voltages, and the proofs for current gain were found throughout the investigated range. The gain value exceeds $10^3$ approaching the theoretically estimated value in this system. The stability and reproducibility of the device characteristics were satisfactory. The results support the candidacy of calcium fluoride for being a vital dielectric in silicon-based functional electronics.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 158-161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ESR Studies of Fast Electron Irradiated Ferroelectric Poly(Vinylidene Fluoride)
Autorzy:
Goslar, J.
Hilczer, B.
Smogór, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043394.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.80.Fe
61.82.Pv
76.30.Rn
77.84.Jd
78.30.Jw
Opis:
Radiation-induced functionalization of ferroelectric poly(vinylidene fluoride) was studied by ESR spectroscopy. The samples were irradiated in the high vacuum of a Van de Graaff accelerator with 1.0 MeV and 1.5 MeV electrons at room temperature and the decay of free radicals was studied after transferring the samples into the air. The samples exhibit a multicomponent ESR spectrum that can be decomposed into: a large asymmetric signal in the centre related to peroxy radicals, a quintet with hyperfine splitting A$\text{}_{F}$ = 4.3 mT centred at g = 2.004, assigned to the in-chain radical (-CF$\text{}_{2}$-CH-CF$\text{}_{2}$-), and a triplet due to an end-chain (-CH$\text{}_{2}$) radical with A$\text{}_{H}$ = 1.6 mT and g = 2.009.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 89-94
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison Between Standard and Modified Judd-Ofelt Theories in a Pr$\text{}^{3+}$-Doped Fluoride Glass
Autorzy:
Goldner, P.
Auzel, F.
Powiązania:
https://bibliotekanauki.pl/articles/1945548.pdf
Data publikacji:
1996-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.50.Hz
42.62.Fi
42.70.Hj
78.50.Ec
Opis:
A method which takes into account normalized oscillator strengths is detailed for the calculation of parameters in Judd-Ofelt theory (B.R. Judd, Phys. Rev. 127, 750 (1962), G.S. Ofelt, J. Chem. Phys. 37, 511 (1962)). In the case of a Pr$\text{}^{3+}$ -doped fluorozirconate glass, the Judd-Ofelt parameters obtained in this way do not depend strongly on the transitions included in the fit. Particularly, it is no longer necessary to exclude the $\text{}^{3}$H$\text{}_{4}$ → $\text{}^{3}$P$\text{}_{2}$ transition from the analysis. Three modified theories (F. Auzel, S. Hubert, P. Delamoye, J. Lumin. 26, 251 (1982), A.A. Kornienko, A.A. Kaminskii, E.B. Dunina, Phys. Status Solidi B 157, 267 (1990)) are also considered but do not improve the calculated intensities when the energy of the 5d level is set to its experimentally determined value. Finally, in connection with 1.3 μ amplification, the 1.3 μ reabsorption ($\text{}^{1}$G$\text{}_{4}$ → $\text{}^{1}$D$\text{}_{2}$) oscillator strength is computed from the various models as well as the 1.3 μ emission branching ratio ($\text{}^{1}$G$\text{}_{4}$ → $\text{}^{3}$H$\text{}_{5}$/$\text{}^{1}$G$\text{}_{4}$ → $\text{}^{3}$H$\text{}_{6}$). The best agreement with experiment is obtained with the standard Judd-Ofelt theory.
Źródło:
Acta Physica Polonica A; 1996, 90, 1; 191-196
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gd$\text{}^{3+}$-RE$\text{}^{3+}$ Exchange Interactions in Rare-Earth Fluoride Crystals (RE = Ce, Nd, Yb)
Autorzy:
Paradowski, M. L.
Misiak, L. E.
Powiązania:
https://bibliotekanauki.pl/articles/2037294.pdf
Data publikacji:
2004-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
75.30.Et
75.30.Hx
76.30.Kg
Opis:
The investigation of Gd$\text{}^{3+}$-doped LaF$\text{}_{3}$, La$\text{}_{0.9}$Ce$\text{}_{0.1}$F$\text{}_{3}$, CeF$\text{}_{3}$, La$\text{}_{0.9}$Nd$\text{}_{0.1}$F$\text{}_{3}$, LiYF$\text{}_{4}$, and LiY$\text{}_{0.9}$Yb$\text{}_{0.1}$F$\text{}_{4}$ single crystals at 4.2 K was carried out in order to study the Gd$\text{}^{3+}$-RE$\text{}^{3+}$ exchange interactions (RE = Ce, Nd, Yb). The exchange interactions were estimated by the application of the molecular-field model at liquid-helium temperature, using the g shift from the isostructural diamagnetic hosts LaF$\text{}_{3}$ and LiYF$\text{}_{4}$ to the paramagnetic hosts. The lattice dynamics is studied by analysing spin-Hamiltonian parameters in the light of the superposition model and the rotational invariance theory for phonon-induced contributions to spin-Hamiltonian parameters. It is suggested from the rotational invariance mechanism for phonon-induced contributions to spin-Hamiltonian parameters that the rotational contributions influence the exchange interactions significantly. Further, the distortions caused by the La$\text{}^{3+}$/Ce$\text{}^{3+}$, La$\text{}^{3+}$/Nd$\text{}^{3+}$, and Y$\text{}^{3+}$/Yb$\text{}^{3+}$ substitutions affect significantly the 4f$\text{}^{7}$ electron-phonon interactions, as well as the exchange interactions. The magnitude of the isotropic exchange interactions is larger for more symmetrical charge distribution of the 4f$\text{}^{7}$ shell.
Źródło:
Acta Physica Polonica A; 2004, 105, 5; 445-457
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Transition, Excitation, and Emission Properties of Poly(N-Vinlycarbazole) Blended with Poly(Vinylidene Fluoride-co-Hexafluoropropene) and Polyvinylpyrrolidone
Autorzy:
Alias, A.
Zabidi, Z.
Harun, M.
Yahya, M.
Ali, A.
Powiązania:
https://bibliotekanauki.pl/articles/1401283.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.60.-j
31.15.bu
81.05.Lg
82.35.Lr
Opis:
We present the results concerning the excitation and emissions spectra of poly(N-carbazole) (PVK) blended with poly(vinylidene fluoride-co-hexafluoropropene), (PVDF-HfP) and polyvinylpyrrolidone (PVP). Thin films of PVK blended with PVDF-HfP (PVK:PVDF-HfP) and PVP (PVK:PVP) were prepared using doctor blade technique on spectrosil substrate. The influences of polymer blends to the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation and emission for each samples. The possible energy transfer and recombination mechanisms have been related with singlet-singlet semi-empirical INDO electronic calculation and FTIR measurements.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1075-1078
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Transition, Excitation, and Emission Properties of Poly(N-Vinlycarbazole) Blended with Poly(Vinylidene Fluoride-co-Hexafluoropropene) and Polyvinylpyrrolidone
Autorzy:
Alias, A.
Zabidi, Z.
Harun, M.
Yahya, M.
Ali, A.
Powiązania:
https://bibliotekanauki.pl/articles/1401439.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.60.-j
31.15.bu
81.05.Lg
82.35.Lr
Opis:
We present the results concerning the excitation and emissions spectra of Poly (N-carbazole) (PVK) blended with poly(vinylidene fluoride-co-hexafluoropropene), (PVDF-HfP) and polyvinylpyrrolidone (PVP). Thin films of PVK blended with PVDF-HfP (PVK:PVDF-HfP) and PVP (PVK:PVP) were prepared using doctor blade technique on spectrosil substrate. The influences of polymer blends on the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation and emission for each sample. The possible energy transfer and recombination mechanisms have been related with singlet-singlet semi-empirical INDO electronic calculation and FTIR measurements.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1430-1433
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Spectroscopic Study of the Dy$\text{}^{3+}$ Doped Double Chloride and Double Fluoride Crystals for Telecommunication Amplifiers and IR Lasers
Autorzy:
Tkachuk, A.
Ivanova, S.
Isaenko, L.
Yelisseyev, A.
Payne, Steve
Solarz, R.
Nostrand, M.
Page, R.
Payne, Stephen
Powiązania:
https://bibliotekanauki.pl/articles/1995823.pdf
Data publikacji:
1999-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.-m
Opis:
In this work we studied spectroscopic characteristics of potassium-lead double-chloride, and lithium-yttrium double-fluoride crystals doped with dysprosium. Objects of research were KPb$\text{}_{2}$Cl$\text{}_{5}$:Dy$\text{}^{3+}$, and LiYF$\text{}_{4}$ (YLF):Dy$\text{}^{3+}$ crystals grown by the Bridgman-Stockbarger technique. We obtained the effective distribution coefficients K$\text{}_{Dy}$=0.95 for LiYF$\text{}_{4}$ :Dy$\text{}^{3+}$, and K$\text{}_{Dy}$=1 for KPb$\text{}_{2}$Cl$\text{}_{5}$:Dy$\text{}^{3+}$. Optical spectra were studied, intensity parameters were determined by the Judd-Ofelt method, and radiative probabilities and branching ratio were calculated. The conclusion was made that the studied crystals can be considered as promising new active media for laser diode pumped solid state lasers. The YLF:Dy$\text{}^{3+}$ crystals are perspective for laser action near 3 mm, and the KPb$\text{}_{2}$Cl$\text{}_{5}$ :Dy$\text{}^{3+}$ for multiwavelength IR lasers, and for 1.3 mm laser diode pumped telecommunication amplifiers.
Źródło:
Acta Physica Polonica A; 1999, 95, 3; 381-394
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-11 z 11

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