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Wyszukujesz frazę "78.50.-w" wg kryterium: Temat


Wyświetlanie 1-15 z 15
Tytuł:
Absorption Spectrum of Ni(II) Ions Doped in Lithium Sodium Potassium Sulphate Single Crystal
Autorzy:
Rama Kumar, R.
Venkata Reddy, B. C.
Powiązania:
https://bibliotekanauki.pl/articles/1933457.pdf
Data publikacji:
1995-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.40.-q
78.50.-w
Opis:
The optical absorption spectra of lithium sodium potassium sulphate doped Ni$\text{}^{2+}$ ions at 300 and 77 K was recorded. The observed bands are assigned as transitions from the ground state $\text{}^{3}$A$\text{}_{2g}$(F) to various excited triplet and singlet states of the Ni$\text{}^{2+}$ ion in octahedral symmetry. The splittings observed for the bands $\text{}^{3}$T$\text{}_{1g}$(F) and $\text{}^{3}$T$\text{}_{2g}$(F) at liquid nitrogen temperature have been explained as due to spin-orbit interaction. The oscillator strengths of the transitions were computed from the area under the curves. From a detailed analysis of the bands of the spectrum, the crystal field parameters B, C, Dq and ξ are evaluated.
Źródło:
Acta Physica Polonica A; 1995, 87, 6; 1023-1029
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetophotoconductivity Due to Intra-Shallow-Donor Transitions in Semi-Insulating GaAs
Autorzy:
Karpierz, K.
Sadowski, M. L.
Grynberg, M.
Powiązania:
https://bibliotekanauki.pl/articles/1890653.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
78.20.Ls
78.50.-w
Opis:
The paper concerns investigations of shallow centres in semi-insulating (SI) GaAs samples. A very sensitive measuring method - magnetophotoconductivity due to intra-shallow-donor transitions - was used. We report the behaviour of intra-impurity transitions as well as an additional structure in low magnetic fields for different far-infrared wavelengths (70.6 μm, 96.5 μm, 118.8 μm, 163 µm). The results are discussed in terms of a fluctuating potential from ionized centres in SI GaAs. The physical mechanism responsible for the low magnetic field structure is proposed.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 291-294
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Precipitation of Nickel Dihalide in Thermally Pretreated NaCl:Ni$\text{}^{2+}$ Crystals
Autorzy:
Morawska-Kowal, T.
Nowak-Woźny, D.
Suszyńska, M.
Powiązania:
https://bibliotekanauki.pl/articles/1931612.pdf
Data publikacji:
1994-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.50.-w
61.72.-y
78.20.-e
Opis:
Optical absorption and the yield stress value of NaCl : Ni$\text{}^{2+}$ crystals were measured as functions of the annealing temperature. Morphology and possible structure types of the NiCl$\text{}_{2}$ particles formed under different annealing conditions have been shortly discussed.
Źródło:
Acta Physica Polonica A; 1994, 86, 3; 363-368
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recombination Processes for Deep Impurity States Degenerate with the Conduction Band
Autorzy:
Świątek, K.
Godlewski, M.
Kaliński, Z.
Przybylińska, H.
Powiązania:
https://bibliotekanauki.pl/articles/1879955.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.50.-w
76.30.Kg
78.55.Hx
Opis:
We report on the studies of autoionization efficiency and the relevant recombination mechanism for Eu$\text{}^{2+}$ in Ca$\text{}_{x}$Cd$\text{}_{1-x}$F$\text{}_{2}$ depending on the energy level position of Eu$\text{}^{2+}$ excited states in respect to the conduction band states.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 243-246
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Physics of Solid-State Laser Materials
Autorzy:
Wojtowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1888052.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Rz
78.50.-w
78.55.-m
Opis:
A survey of the physical properties of solid state materials activated with d$\text{}^{2}$, d$\text{}^{3}$ and d$\text{}^{8}$ transition metal ions is presented in the context of tunable laser operation. An emphasis is put on common characteristics of all three systems, like a strong electron-phonon coupling and similar electronic structures. The conditions necessary to obtain a tunable operation and to avoid an overlap of the excited state absorption and emission are formulated. It is shown that the d$\text{}^{3}$ configuration system has the largest range of allowed values of the crystal field parameter 10Dq.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 193-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intra-Shallow-Donor Photoconductivity in Semi-Insulating GaAs
Autorzy:
Karpierz, K.
Sadowski, M. L.
Powiązania:
https://bibliotekanauki.pl/articles/1877562.pdf
Data publikacji:
1991-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
78.20.ls
78.50.Ec
78.50.Ge
Opis:
The far-infrared photoconductivity of a semi-insulating GaAs sample was measured at 4.2 K as a function of magnetic field up to 7 T. Apart from a peak corresponding to the 1s - 2p$\text{}_{+1}$ transition of the hydrogen-like shallow donor, a well-pronounced structure was observed which does not appear in n-type GaAs.
Źródło:
Acta Physica Polonica A; 1991, 79, 1; 121-124
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence and Photoconductivity of Cerium Compounds
Autorzy:
Yen, W. M
Basun, S.
Happek, U.
Raukas, M.
Powiązania:
https://bibliotekanauki.pl/articles/1945563.pdf
Data publikacji:
1996-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
78.50.Ec
78.55.Hx
Opis:
The study of the luminescence properties of rare earth doped systems historically focuses on systems which exhibit strong luminescence. More recently, extensive studies on materials with high quantum efficiency are in part motivated by the search for new phosphor and scintillator materials. However, a thorough study of certain systems which show very low quantum yield will certainly lead to a better understanding of phosphor materials and rare earth systems in general. As an example of recent studies which address both the fundamental question of relaxation processes in rare earth doped systems and phosphor applications we present studies on cerium-doped lutetium oxide crystals which are characterized by a complete quenching of the 5d-4f luminescence and compare its optical properties to that of very efficient cerium doped phosphor material, lutetium oxyorthosilicate. To find the mechanisms which lead to the different quantum efficiency in these systems, extensive absorption, photoexcitation and photoconductivity studies were performed on single crystals. We demonstrate that the radically different emission properties of the investigated systems originate in small but crucial differences in the location of the emitting 5d level of the cerium ion with respect to the conduction band of the host - a general result which can be applied to a broad range of materials.
Źródło:
Acta Physica Polonica A; 1996, 90, 2; 257-266
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetotransmission Measurements of Intra-Shallow-Donor Transitions in Semi-Insulating GaAs
Autorzy:
Karpierz, K.
Kożuchowski, K.
Grynberg, M.
Powiązania:
https://bibliotekanauki.pl/articles/1920976.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
78.20.Ls
78.50.Ge
Opis:
In this paper we present the results of an investigation of the 1s-2p$\text{}_{+}$ intra-shallow-donor transition by means of an extremely difficult magnetotransmission experiment performed on semi-insulating GaAs. We report the temperature dependence of the transition intensity. We noticed the absence in the absorbance spectra of a well-pronounced structure which is observed at low magnetic fields in photoconductivity measurements. The results are discussed in terms of a fluctuating potential from ionized centres in semi-insulating GaAs.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 617-619
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Picosecond Transient Absorption of Xanthene Dyes
Autorzy:
Berndt, O.
Bandt, F.
Eichwurzel, I.
Stiel, H.
Powiązania:
https://bibliotekanauki.pl/articles/1994630.pdf
Data publikacji:
1999-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.50.+w
33.50.-j
78.47.+p
Opis:
After one- and two-colour ps-excitation the transient absorption of rose bengal, erythrosin B and eosin Y in the spectral range from 450 to 670 nm was probed using picosecond continuum pulses generated in H$\text{}_{2}$O-D$\text{}_{2}$O mixture. Our experiments showed for all dyes a high T$\text{}_{1}$-T$\text{}_{n}$ absorption signal above 590 nm where no ground state absorption occurs. These excited triplet states can be effectively populated by a delayed second pump pulse. Their properties with special attention to reverse intersystem crossing processes from T$\text{}_{n}$ to S$\text{}_{x}$ are discussed.
Źródło:
Acta Physica Polonica A; 1999, 95, 2; 207-220
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrafast Energy Relaxation and Excitation Delocalization in Excited States of Zinc Porphyrin Dimers and Trimer
Autorzy:
Yamazaki, I.
Akimoto, S.
Yamazaki, T.
Shiratori, H.
Osuka, A.
Powiązania:
https://bibliotekanauki.pl/articles/1994082.pdf
Data publikacji:
1999-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.50.+w
78.47.+p
Opis:
Ultrafast excited-state relaxation process has been studied with zinc porphyrin dimers and circular trimer. Following 80 fs excitation at Soret band (420 nm) or Q band (580 nm) of zinc porphyrin, the fluorescence decay curves exhibit ultrafast decays with lifetimes of 80 fs in o-dimer, 450 fs in trimer and 540 fs in m-dimer. The timeresolved fluorescence spectra show that the fast decay process correspond to disappearance of monomer-like emission followed by red-shifted and broaden spectra. These ultrafast processes are assigned as due to excitation transfer among monomers and delocalization of excitation yielding excitonic states.
Źródło:
Acta Physica Polonica A; 1999, 95, 1; 105-120
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of Gastric Cancer from Speckle Patterns
Autorzy:
Andrade-Eraso, C.
Patiño-Velasco, M.
Vásquez-López, J.
León, J.
Bolaños-Pantoja, G.
Trivi, M.
Powiązania:
https://bibliotekanauki.pl/articles/1490749.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.68.+m
42.87.-d
87.50.W-
Opis:
Speckle technique is based on the light intensity distribution randomly formed when a laser light is reflected on a rough surface, creating a pattern of illuminated grains (constructively) and dark (destructive) on scales of 1 μm. When the samples are displaced or deformed, the speckle pattern is altered. In this paper we present speckle patterns obtained from samples of gastric mucosa that is physically altered for the carcinogenesis process. Biopsies were studied with different diagnoses and were grouped according to the characteristics of speckle patterns. Speckle patterns were obtained by illuminating the samples with green laser. Morphological parameters of the speckle patterns reveal existence of 3 descriptors: the average grain size, hydraulic radius and the radio of the Weddel disc, which showed a high, intermediate and low value. The comparison shows agreement between the histopathological diagnosis and the values obtained by the speckle technique, making this technique emerge as a new classification system for quantitative diagnosis of precancerous lesions.
Źródło:
Acta Physica Polonica A; 2012, 121, 1; 62-64
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoinduced Phenomena in Sulphur Crystals and Films
Autorzy:
Dovgii, Ya. O.
Kityk, I. V.
Yablonovska, O. G.
Powiązania:
https://bibliotekanauki.pl/articles/1920534.pdf
Data publikacji:
1992-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
71.55.Gs
78.50.Ge
Opis:
The irradiation of sulphur crystals and films with ultraviolet light induces the change of transmission in the visible part of spectra. It was found that these phenomena exist only at low temperatures (4.2-50 K). The behaviour of optical transparency as a function of time after switching the rumination off was investigated. These dependences are essentially different for the films and crystals. In order to understand the origin of these phenomena the structural investigation was conducted. Very unusual behaviour of darkening kinetics was obtained.
Źródło:
Acta Physica Polonica A; 1992, 81, 3; 405-408
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity Near Transition to Insulating State in MoC Ultrathin Films Studied by Subkelvin STM
Autorzy:
Szabó, P.
Neilinger, P.
Trgala, M.
Grajcar, M.
Samuely, P.
Powiązania:
https://bibliotekanauki.pl/articles/1372334.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.50.+r
74.78.-w
74.81.-g
Opis:
We study the homogeneously disordered MoC thin films with thicknesses of 10 and 5 nm and the superconducting transition temperatures near 6 and 4 K, significantly decreased as compared to the bulk $T_{c}$=8.32 K due to a disorder. The scanning tunnelling spectroscopy reveals in the thicker sample a BCS superconducting energy gap Δ with a broadening parameter Γ equal to about 10 per cent of Δ. Remarkably, Γ increases with temperature. The thinner, more disordered sample shows a gapped superconducting density of states but without any coherence peaks at the gap edge, which could not be approximated by the BCS DOS. Moreover, the reduced DOS around the Fermi level persists above the resistive transition temperature reminding the pseudo-gap known from high-$T_{c}$ cuprates.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 368-369
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoconductivity Study of Sputter-Deposited $Cu_2O$ Films
Autorzy:
Bhattacharyya, S.
Reppin, D.
Sanguino, P.
Ayouchi, R.
Polity, A.
Schwarz, R.
Hofmann, D.
Meyer, B.
Powiązania:
https://bibliotekanauki.pl/articles/1492344.pdf
Data publikacji:
2011-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.-w
73.50.-h
73.61.-r
Opis:
Cuprous oxide $(Cu_2O)$ thin films were deposited by radio frequency sputtering technique on fused silica substrates. The X-ray diffraction study of the $Cu_2O$ samples showed reflections from (111) and (200) planes of cubic $Cu_2O$. The samples were then annealed at 1008 K in nitrogen $(N_2)$ atmosphere. Annealed samples indicated strain relaxation. The samples were then characterized optically by measuring the transmittance using an ultraviolet-visible-near infrared photospectrometer. The band gap of the as-deposited samples were found to be ≈ 2.1 eV, whereas the annealed samples had a band gap of ≈ 2.6 eV. The transient photocurrent decay measurements of the annealed films indicated slow non-exponential power law decays in several time windows, indicating multiple trapping of the carriers in the deep defects within the band gap. The steady-state photo and dark current measurement and persistent photocurrent (PPC) was carried out on the annealed samples. In general, the photocurrent was found to be much smaller than the dark current. The steady-state and transient photocurrent measurements were utilized to determine the carrier lifetime-mobility product, 〈μτ 〉 of the samples and to determine the carrier mobility, 〈μ 〉.
Źródło:
Acta Physica Polonica A; 2011, 120, 6A; A-011-A-014
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time-Reversal Invariant Topological Superconductivity in Quasi-One-Dimensional Structures
Autorzy:
Mammadova, S.
Nakhmedov, E.
Alekperov, O.
Powiązania:
https://bibliotekanauki.pl/articles/1398788.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.-w
71.10.Pm
71.70.Ej
74.50.+r
Opis:
It is shown that a time-reversal invariant topological superconductivity can be realized in a quasi-one-dimensional structure, which is fabricated by filling the superconducting materials into the periodic channel of dielectric matrices like zeolite and asbestos under high pressure. The topological superconducting phase sets up in the presence of large spin-orbit interactions when s-wave intra-wire and d-wave inter-wire pairings take place. Kramers pairs of Majorana bound states emerge at the edges of each wire. The time-reversal topological superconductor belongs to DIII class of symmetry with a Z₂ invariant.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 800-802
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-15 z 15

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