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Wyświetlanie 1-25 z 118
Tytuł:
Hexammine Nickel Complex: Cooperative Rotation of Six NH$\text{}_{3}$ Groups
Autorzy:
Sczaniecki, P. B.
Powiązania:
https://bibliotekanauki.pl/articles/1931836.pdf
Data publikacji:
1994-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
Opis:
Electrostatic interactions between NH3 groups undergoing a correlated rotation are calculated with reference to the nickel hexammine complexes [Ni(NH$\text{}_{3}$)$\text{}_{6}$]$\text{}^{2+}$ The results demonstrate the angular dependence of the cis and trans arrangements of the model ammonia triangles. The previously defined four maxima and four minima are identified.
Źródło:
Acta Physica Polonica A; 1994, 86, 6; 1021-1026
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanisms of Nonuniform Line Broadening
Autorzy:
Wilamowski, Ż.
Przybylińska, H.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1931943.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.20.+q
76.30.-v
Opis:
When the spin relaxation time of paramagnetic impurities at different magnetic sites differs by orders of magnitude then instead of resonance line broadening, rather a decay of the line amplitude is expected. In particular, the sp-d coupling of magnetic impurities to shallow impurities leads to a nonuniform distribution of the longitudinal relaxation rates of local spins.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 181-184
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pretransition Phenomena in Fast-Proton Conductors
Autorzy:
Waplak, S.
Bednarski, W.
Ostrowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/2043554.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
66.30.-h
Opis:
In this paper we present recent experimental results related to nonlinear crystal field fluctuations and current flow in K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ fast-proton conductor far below the transition temperature T$\text{}_{g}$. The results for crystalline and powdered samples are quantitatively explained in the framework of soliton model of charge transport.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 261-270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Effect in Magnetic Dependent Dissipation in High Temperature Superconductors
Autorzy:
Stankowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2043552.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
76.30.-v
Opis:
Electron paramagnetic resonance in ac dissipation was observed due to the Cooper pairs breaking up to their quasiparticle state. This phenomenon is the result of a flux motion on a pinning centers in high temperature superconducting materials. The detection of ac dissipation was performed in a low ac field (15 and 22 MHz) as well as in microwave range. Vortex motion hysteresis loop with magnetic field modulation of 15 Hz was recorded. Besides V-shaped dependence of ac power dissipation P(B), a direct electron paramagnetic resonance signal related to Cooper pairs → quasiparticle fluctuation was observed.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 243-246
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR and MMMA Study of C$\text{}_{60}$ upon K-Doping
Autorzy:
Kempiński, W.
Stankowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933662.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.Wz
76.30.-v
Opis:
EPR and ΜΜMΑ studies of C$\text{}_{60}$ upon K-doping have been performed. Two different and well separated EPR narrow lines were detected for C$\text{}_{60}^{1-}$ and C at temperatures below 100 K. Time dependent changes in the intensities of both and C$\text{}_{60}^{3-}$ lines were observed when the system undergoes an eutectoid transformation. The evolution of superconductivity with two T$\text{}_{c}$ related to different valences (v) of C$\text{}_{60}^{v}$ ion radicals have been found.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 549-552
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Dating of Hydroxyapatite from Fossil Bones. Transient Effects after γ and UV Irradiation
Autorzy:
Wencka, M.
Hoffmann, S. K.
Hercman, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043612.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
65.90.+i
Opis:
ESR measurements at room temperature have been performed on fossil bones of cave bear (from Magurska Cave of the Tatra Mountains) and mammoth (from Dniestr River). Various paramagnetic centres related to defects in hydroxyapatite were identified. The ESR spectrum is dominated by Mn$\text{}^{2+}$ lines and free radical centres CO$\text{}_{2}^{-}$ and CO$\text{}_{3}^{-}$. Suitability of various EPR lines for the dating was evaluated. The spectra are affected by γ-ray and UV irradiation which produce new relatively unstable (transient) radical centres. From their decay curves we determined the delay period (waiting time) between irradiation and ESR dating measurements. For γ-rays the period is about 15 days and depends on the chosen ESR line. UV generates mainly surface O$\text{}^{-}$ centres which decay practically after a few days. The ESR dating of the bear bones using an additive dose method given the age t = 21.7 kiloyears (ky), whereas from radionuclide Th/U method t= 34 ky and from radiocarbon $\text{}^{14}$C method t > 33.1 ky.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 331-337
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Spectra of the Genuine-Organic and Metal-Organic TCNQ-Based Anion Radical Salts
Autorzy:
Botko, M.
Čižmár, E.
Kajňaková, M.
Feher, A.
Powiązania:
https://bibliotekanauki.pl/articles/1368637.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Xx
76.30.-v
Opis:
We have measured the electron paramagnetic resonance spectra of genuine-organic anion-radical salts $[Me-2,6-di-Me-Py](TCNQ)_{2}$, $[Me-3,5-di-Me-Py](TCNQ)_{2}$, $[N-Me-OH-Me-Py](TCNQ)_{2}$, $[N-Et-OH-Me-Py](TCNQ)_{2}$, and metal-organic anion-radical salt $[Mn-phen_{3}](TCNQ)_{2}$·$H_{2}O$ in the temperature range from 2 K to 300 K in the X-band frequency range. A comparison study of the shape of spectra, g-factors and linewidths with respect to the composition and crystal structure of studied compounds is presented. While the genuine-organic anion-radical salts display a typical EPR response originating from TCNQ pairs, the spectra of metal-organic anion-radical salt are dominated by the contribution of transition metal.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 252-253
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Binding of the Trace Elements: Cu(II) and Fe(III) to the Native and Modified Nutritive Potato Starches Studied by EPR
Autorzy:
Śmigielska, H.
Lewandowicz, G.
Goslar, J.
Hoffmann, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/2043599.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
87.15.-v
Opis:
The Cu(II) and Fe(III) ions have been adsorbed by four potato starches of different degrees of oxidation (different numbers of COOH groups replacing host CH$\text{}_{2}$OH groups): native (no oxidized), white (pudding) with oxidation degree of 0.04%, gelating (0.1%), and LUBOX starch (0.5%). Concentration of the ions in starches was determined from atomic absorption and EPR spectrum intensity. For small concentration of the adsorbed ions (below 4 mg/g) nearly all ions are adsorbed from the solution. EPR shows that adsorbed copper(II) ions are chemically bonded to the starch molecules (preferably) at COOH sites and uniformly dispersed in the starch structure. The complexes are typical of octahedral or square-quadratic coordination with spin-Hamiltonian parameters g$\text{}_{ǁ}$=2.373, g$\text{}_{⊥}$= 2.080, A$\text{}_{ǁ}$=12.1 mT, A$\text{}_{⊥}$=1.0 mT. For higher concentrations the Cu(II) displays a tendency to clustering. Iron(III) ions are introduced into starch in a form of clusters mainly, even for the smallest concentration. The highest concentrations of both Cu(II) and Fe(III) were observed in LUBOX starch having the highest degree of oxidation.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 303-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Effects in ESR Spectra of Radical Centres in Dripstone Calcite Samples Used for ESR Dating
Autorzy:
Wencka, M.
Hoffmann, S. K.
Krzyminiewski, R.
Mielcarek, S.
Powiązania:
https://bibliotekanauki.pl/articles/2043694.pdf
Data publikacji:
2005-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
65.90.+i
Opis:
Natural calcite samples were collected from the dripstone layers of the Black Cave of the Tatra Mountains. ESR spectra, thermal analysis, and thermoluminescence data were analysed to obtain a consistent picture of the calcite properties. The ESR spectra were analysed using computer enhanced resolution spectra and an influence of the thermal annealing on intensity of individual ESR lines was measured. These results together with the effects of γ-irradiation in ESR spectra allowed one to discriminate between ESR lines from various paramagnetic centres. A general conclusion of the paper is that in the ESR dating the outer ESR lines of CO$\text{}_{3}^{-}$ (g=2.0125) and CO$\text{}_{2}^{-}$ (g=1.9980) radicals should be used instead of the commonly used multicomponent central line.
Źródło:
Acta Physica Polonica A; 2005, 108, 3; 491-503
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Spin Resonance Spectra of Fe$\text{}^{3+}$ Ions in SrLaAlO$\text{}_{4}$ and SrLaGaO$\text{}_{4}$ High-T$\text{}_{c}$ Substrates
Autorzy:
Jabłoński, R.
Pajączkowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1964358.pdf
Data publikacji:
1997-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
61.72.Hh
Opis:
New results concerning paramagnetic defects in SrLaAlO$\text{}_{4}$ and SrLaGaO$\text{}_{4}$ high-T$\text{}_{c}$ substrates connected with unavoidable impurity Fe$\text{}^{3+}$ are reported. The identification was checked by measuring the spectra in SrLaAlO$\text{}_{4}$ crystals intentionally doped with 0.5 at.% Fe. Angular dependences of three lines were distinguished at X-band frequency in the temperature range from 4 K to 300 K. We attribute these lines to the transitions inside the doublets ±1/2, and "forbidden" doublets ±3/2, ±5/2, respectively. By diagonalization of spin-Hamiltonian, parameters |D| > 1.2 cm$\text{}^{-1}$, |E| ≈ 0.1 cm$\text{}^{-1}$ and g$\text{}_{x}$=g$\text{}_{y}$=g$\text{}_{z}$= 1.987(13) for SrLaAlO$\text{}_{4}$ and SrLaGaO$\text{}_{4}$ were calculated and within the margin of error they were of the same value.
Źródło:
Acta Physica Polonica A; 1997, 92, 1; 173-176
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of Phase Transitions in (NH$\text{}_{4}$)$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ Crystal by Means of Mn$\text{}^{2+}$ EPR Spectra
Autorzy:
Bednarski, W.
Waplak, S.
Powiązania:
https://bibliotekanauki.pl/articles/1952756.pdf
Data publikacji:
1996-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
76.30.-v
Opis:
EPR of Mn$\text{}^{2+}$ impurity ion in the (NH$\text{}_{4}$)$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ crystal is studied in the temperature range 80-420 K. It is shown that Mn$\text{}^{2+}$ substitutes NH$\text{}_{4}^{+}$(I) ion and is coordinated in deformed oxygen octahedron in which takes two "off-center" positions. Its spin-Hamiltonian parameters and direction cosines of crystal field are determined. The successive EPR line splitting for three phase transitions is discussed.
Źródło:
Acta Physica Polonica A; 1996, 90, 6; 1185-1192
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vibronic Effects in EPR Spectra of (NH$\text{}_{4}$)$\text{}_{2}$Cu(BeF$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$0 Single Crystal
Autorzy:
Hoffmann, S.
Gomółka-Marciniak, M.
Powiązania:
https://bibliotekanauki.pl/articles/1929355.pdf
Data publikacji:
1993-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
71.70.Ej
Opis:
Angular variations of the g-factors and linewidth value were recorded at X-band, at room temperature, and at 77 K. The temperature dependence of the g-factors was measured along the principal g-tensor axes in the temperature range from 4.2 K to 300 K. The rigid lattice g-factors at 4.2 K are: g$\text{}_{z}$ = 2.428, g$\text{}_{y}$ = 2.138, and g$\text{}_{x}$ = 2.058. The g$\text{}_{x}$ value very slowly increases linearly on heating, whereas g$\text{}_{z}$ and g$\text{}_{y}$ nonlinearly tend towards their average value. This is a typical behaviour of Cu(II) EPR in Tutton salt crystals, however the g(T) dependence is much less pronounced in (NH$\text{}_{4}$)$\text{}_{2}$Cu(BeF$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$0 as compared to the Cu(II) doped salts. The results are described in terms of the two vibronic coupling models of the strong Jahn-Teller effect. It is shown that the models are not adequate to describe the vibronic g-factor behaviour in paramagnetic Cu(II) crystals which is attributed to the cooperative Jahn-Teller effect existing in these crystals.
Źródło:
Acta Physica Polonica A; 1993, 83, 6; 817-830
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Application in the Study of K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ Proton Conductor Doped with Mn$\text{}^{2+}$ or VO$\text{}^{2+}$ Ions
Autorzy:
Waplak, S.
Powiązania:
https://bibliotekanauki.pl/articles/1931810.pdf
Data publikacji:
1994-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
76.30.-v
Opis:
The EPR of Mn$\text{}^{2+}$- or VO$\text{}^{2+}$-doped superprotonic conductor K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ is studied in the 80-471 K temperature range. VO$\text{}^{2+}$ EPR spectrum reveals diffusion induced merging of proton transferred superhyperfine structure above 380 K. Line width anomaly is observed in Mn$\text{}^{2+}$ EPR spectrum which is attributed to the intrabond and interbond proton motions, these lead to high protonic conductivity. It is shown that paramagnetic centers namely of electronic spin greater than 1, with excess charge compensated by the protonic vacancy, are good probes to monitor the protonic conductivity on molecular level.
Źródło:
Acta Physica Polonica A; 1994, 86, 6; 939-945
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the Magnetic Field Distribution in the Bi2212 superconducting Single Crystal by the Scanning EPR-Probe
Autorzy:
Drulis, H.
Folcik, L.
Drulis, M.
Zaleski, A.
Suleimanov, N. M.
Powiązania:
https://bibliotekanauki.pl/articles/1968771.pdf
Data publikacji:
1998-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.72.-h
76.30.-v
Opis:
The profile of the magnetic field distribution over the surface of superconducting sample is studied by the scanning an electron paramagnetic resonance microprobe. The magnetic field distribution is mapped from the measurements of the spin probe EPR-signal shift.
Źródło:
Acta Physica Polonica A; 1998, 93, 2; 403-407
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Angular Dependences of ESR Parameters in Antiferroquadrupolar Phase of CeB₆
Autorzy:
Semeno, A.
Gilmanov, M.
Sluchanko, N.
Krasnorussky, V.
Shitsevalova, N.
Filipov, V.
Flachbart, K.
Demishev, S.
Powiązania:
https://bibliotekanauki.pl/articles/1032654.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.30.Kg
Opis:
Angular dependences of ESR line parameters (g-factor and linewidth Δ H) were experimentally explored in the antiferroquadrupolar phase of heavy fermion system CeB₆ at T=1.8 K. The data were obtained in two experimental geometries with different mutual directions of the wavevector k and the external magnetic field H at frequency of f=60 GHz. A g-factor anisotropy was found: while g-factors for [110] and [111] directions are close to each other (g ≈1.6), it is considerably higher (g ≈1.75) for [100]. The obtained angular dependence g(Θ) was compared with the theoretically predicted g-factor behavior for the Γp₈ state of Ce³⁺ ion in antiferroquadrupolar phase of CeB₆. It turns out that the experimental g-factor is considerably smaller at all angles than the theoretically calculated limits (2
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1060-1062
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR Study of Cu$\text{}^{2+}$ Doped Fast-Proton Conductor K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ in the Temperature Range 100-450 K
Autorzy:
Ostrowski, A.
Bednarski, W.
Waplak, S.
Powiązania:
https://bibliotekanauki.pl/articles/2037037.pdf
Data publikacji:
2003-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.50.-f
76.30.-v
Opis:
The K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ doped with Cu$\text{}^{2+}$ ion was studied in detail by X-band CW EPR. Two kinds of Cu$\text{}^{2+}$ complexes (magnetically and structurally nonequivalent) denoted as Cu$\text{}^{2+}$(I) and Cu$\text{}^{2+}$(II) were found. Spin-Hamiltonian parameters, direction cosines, and coordination of Cu$\text{}^{2+}$ ion were determined at room temperature. The superhyperfine structure was observed below 250 K as a result of interacting of Cu$\text{}^{2+}$ ion with four equivalent protons (I=1/2). Temperature studies of K$\text{}_{3}$H(SO$\text{}_{4}$)$\text{}_{2}$ crystal show that interbond motion as a precursor of superprotonic phase transition occurs at above≈250 K.
Źródło:
Acta Physica Polonica A; 2003, 104, 6; 549-558
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Vibronic Dynamics of Cu(H$\text{}_{2}$O)$\text{}_{6}$ Complexes and Electron Spin Relaxation in Temperature Dependence of EPR Linewidth in Diamagnetic Tutton Salt Single Crystals
Autorzy:
Hoffmann, S. K.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047171.pdf
Data publikacji:
2006-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.90.+t
76.30.-v
Opis:
EPR linewidth of Cu$\text{}^{2+}$ in the Tutton salt crystals weakly depends on temperature at low temperatures and then it rapidly grows above 60 K. We present detailed results of measurements and analysis for $\text{}^{63}$Cu$\text{}^{2+}$ in K$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6 H$\text{}_{2}$O, K$\text{}_{2}$ Zn(SO$\text{}_{4}$)$\text{}_{2}$·6D$\text{}_{2}$O, (NH$\text{}_{4}$)$\text{}_{2}$Mg(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O and Cs$\text{}_{2}$Zn (SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O in a temperature range of 4.2-300 K and compare them with already published electron spin-lattice relaxation data. The relaxation contributes weakly to the linewidth which is dominated by molecular dynamics and grows exponentially with temperature. To describe this we are discussing the influence of jumps between two sites of Cu$\text{}^{2+}$ complexes in a slow motion region where the sites are differently thermally populated. This case has not been considered so far. We have derived appropriate expressions describing the contribution of jumps to the linewidth which allows the determination of the jump rate and energy difference δ$\text{}_{A,B}$ between the two sites being two Jahn-Teller distorted configurations of the vibronic Cu(H$\text{}_{2}$O)$\text{}_{6}$ complexes. The jump rate 1/τ strongly depends on temperature and reaches 10$\text{}^{9}$ s$\text{}^{-1}$ at room temperature, whereas theδ$\text{}_{A,B}$ varies from 117 cm$\text{}^{-1}$ for K$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6D$\text{}_{2}$O to 422 cm$\text{}^{-1}$ for Cs$\text{}_{2}$Zn(SO$\text{}_{4}$)$\text{}_{2}$·6 H$\text{}_{2}$O. The comparison with vibronic level splitting, which varies in the range of 67-102 cm$\text{}^{-1}$, indicates that the reorientation mechanism involves phonon induced tunnelling via excited vibronic levels. These reorientations do not contribute, however, to the spin-lattice relaxation which is governed by ordinary two-phonon relaxation processes in the whole temperature range. Thus, the reorientations and spin relaxation are two independent phenomena contributing to the total linewidth.
Źródło:
Acta Physica Polonica A; 2006, 110, 6; 807-816
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Paramagnetic Resonance Study of Organic Radicals in Some Herbal Plants
Autorzy:
Krupska, A.
Wojtowicz, E.
Augustyniak-Jabłokow, M.
Powiązania:
https://bibliotekanauki.pl/articles/1398973.pdf
Data publikacji:
2016-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.30.Rn
Opis:
In this work we show the impact of the roasting process on the properties of organic radicals in some herbal products added to cereal coffee. The EPR study shows the presence of radicals in dried herbal products, both natural and roasted. Changes in the relative intensity of the EPR signal and in the g-factor for unroasted and roasted plant material can be observed. This indicates to the recombination processes of radicals. Roasting process increases the number of radicals. The analysis of EPR spectra show that they consist of two Gaussian lines which indicate that there are at least two different kinds of radicals. The values of g-factor about 2 may be derived from a number of very different radicals. For this reason the identification of such radicals is not strictly possible.
Źródło:
Acta Physica Polonica A; 2016, 129, 6; 1201-1204
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Properties of High-Temperature Superconductor DyBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ from Critical Fields and Specific Heat Studies
Autorzy:
Kołodziejczyk, A.
Kozłowski, A.
Chmist, J.
Zalecki, R.
Ściężor, T.
Tarnawski, Z.
Woch, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/1929388.pdf
Data publikacji:
1993-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
76.30.-v
Opis:
The lower and upper critical fields, as well as the specific heat were measured as a function of temperature for good quality DyBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ high-temperature superconductor in the vicinity of superconducting transition temperature T$\text{}_{c}$ = 91.2 K. The number of superconducting and normal state electronic quantities were determined basing on the Ginzburg-Landau-Abrikosov-Gorkov theory. It is argued that on the basis of this BCS-like theory one can describe the superconducting properties and, in combination with some information on the electronic structure, also the magnetic properties of high-temperature superconductors.
Źródło:
Acta Physica Polonica A; 1993, 84, 1; 127-138
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Paramagnetic Resonance Study of the [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{3}$Cl$\text{}_{11}$ Monocrystal Doped with Cu$\text{}^{2+}$ ion
Autorzy:
Ostrowski, A.
Bednarski, W.
Waplak, S.
Czapla, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2030763.pdf
Data publikacji:
2002-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
05.70.Fh
Opis:
The paper reports the electron paramagnetic resonance investigation of Cu$\text{}^{2+}$ doped [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{3}$Cl$\text{}_{11}$ (DMACC) monocrystal. DMACC:Cu$\text{}^{2+}$ was studied in the temperature range (6÷293) K. We did not observe any anomalies of spin-Hamiltonian parameters of Cu$\text{}^{2+}$ ion corresponding to the temperature anomalies observed in dielectric studies. The electron paramagnetic resonance anomaly recorded at about 40 K results from the subtle changes in bonds angles and Cu-Cl distances and suggests the smooth second order transition.
Źródło:
Acta Physica Polonica A; 2002, 101, 6; 893-899
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zero-Field Splitting Parameters of $Cr^{3+}$ in Lithium Potassium Sulphate at Orthorhombic Symmetry Site
Autorzy:
Pandey, S.
Kripal, R.
Powiązania:
https://bibliotekanauki.pl/articles/1400393.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
76.30.Fc
Opis:
The superposition model is used to investigate the crystal field parameters, $B_{kq}$ of $Cr^{3+}$ in lithium potassium sulphate. The zero field splitting parameters D and E are then determined using microscopic spin Hamiltonian theory and compared with the experimental values obtained by electron paramagnetic resonance. Both zero field splitting parameters D and E evaluated theoretically are in good agreement with the experimental values. The results suggest that the $Cr^{3+}$ ion occupies substitutional K^{+} site in lithium potassium sulphate.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 101-105
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XANES Experiments for High-Temperature Superconductors
Autorzy:
Kołodziejczyk, A.
Powiązania:
https://bibliotekanauki.pl/articles/1920888.pdf
Data publikacji:
1992-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
76.30.-v
Opis:
The paper presents the results of XANES (X-ray Absorption Near Edge Structure) experiments, of the high-temperature superconductors of Y-Ba-Cu-O-type carried out at the Cu L$\text{}_{II,III}$- and O K$\text{}_{I}$-edges using synchrotron radiation and the KMC double monochromator and SX-700 grading monochromator beamlines of BESSY/Berlin synchrotron storage ring. The aim of the paper is to show that the XANES studies are well suited for characterization of the local electronic structure of the high-temperature superconductors.
Źródło:
Acta Physica Polonica A; 1992, 82, 2; 273-281
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconductivity of Carbon Materials - Unstable Phases
Autorzy:
Kempiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/2038391.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
74.70.Wz
Opis:
Different intercalated carbon systems: K$\text{}_{x}$C$\text{}_{60}$, Rb$\text{}_{x}$C$\text{}_{60}$ as well as highly oriented pyrolytic graphite + potassium with unstable structural and superconducting behavior were investigated with the EPR and magnetically modulated microwave absorption techniques. Three characteristic, well-separated EPR signals were observed for A$\text{}_{x}$C$\text{}_{60}$ (A = K or Rb) systems at the early stages of doping process. We ascribed these signals to C$\text{}_{60}^{+}$, C$\text{}_{60}^{1-}$, and C$\text{}_{60}^{3-}$ radicals. Evolution of the EPR spectrum characterizes different phases of K$\text{}_{x}$C$\text{}_{60}$ system including superconducting one. Two superconducting phases with T$\text{}_{c}^{(1)}$=(21±0.5) K (unstable) and T$\text{}_{c}^{(2)}$=(18.5±0.5) K (final, stable) were distinctly separated for K$\text{}_{x}$C$\text{}_{60}$ system. For C$\text{}_{60}$ intercalated by rubidium a similar evolution of EPR spectrum is observed. Prior to well-defined superconducting Rb$\text{}_{3}$C$\text{}_{60}$ phase was created, strong instabilities of the magnetically modulated microwave absorption signal were observed at the narrow part of the doping process. For potassium intercalated highly oriented pyrolytic graphite, EPR oscillations below 100 K were observed as well as Josephson hysteresis loops were registered at 5 K.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 627-636
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$\text{}^{13}$C High Resolution NMR Study of Methyl-Diethyl Sulfonium TCNQ 1:2 Complex
Autorzy:
Firlej, L.
Pęcherz, J.
Bernier, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933380.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.30.-v
Opis:
Solid state high resolution $\text{}^{13}$C NMR studies of a 1 : 2 charge transfer complex of TCNQ with diethyl-methyl sulfonium S + Et$\text{}_{2}$Me(TCNQ)$\text{}_{2}$ are presented. The metallic shifts of TCNQ resonances are interpreted as due to the Pauli paramagnetism of conducting electrons and quantitatively connected with inhomogeneous spin density distribution over (TCNQ2)¯ dimer. A singularity of NMR parameters at T = 330 K is observed and described as a structural phase transition occurring in the S + Et$\text{}_{2}$Me cation sublattice.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 829-834
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical Detection of Paramagnetic Centres in Activated Oxyfluoride Glass-Ceramics
Autorzy:
Rogulis, U.
Fedotovs, A.
Antuzevics, A.
Berzins, Dz.
Zhydachevskyy, Ya.
Sugak, D.
Powiązania:
https://bibliotekanauki.pl/articles/1029682.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.70.Hb
76.30.-v
Opis:
Electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD) and EPR detected via MCD (MCD-EPR) investigations have been performed on rare-earth activated oxyfluoride glasses and glass-ceramics. Er³⁺, Gd³⁺, and Mn²⁺ activators in oxyfluoride glass-ceramics show paramagnetic MCD behaviour and the MCD-EPR has been detected. The results of the MCD-EPR measurements for the Er-doped oxyfluoride glass-ceramics showed that Er³⁺ ions in the CaF₂ crystallites in these ceramics embed only in the cubic symmetry environment, similarly to the previous observations of cubic Gd³⁺ centres in the glass-ceramics containing CaF₂. Finally, the correlation of optics and paramagnetic centres is discussed for Mn-doped YAlO₃ ceramics.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 785-788
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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