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Wyszukujesz frazę "76.60.-k" wg kryterium: Temat


Tytuł:
$\text{}^{11}$B-NMR Study of $SmB_6$ under Pressure
Autorzy:
Pristáš, G.
Mito, T.
Kohara, T.
Gabáni, S.
Reiffers, M.
Flachbart, K.
Takeshita, N.
Shitsevalova, N.
Powiązania:
https://bibliotekanauki.pl/articles/1534330.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
62.50.-p
71.28.+d
Opis:
We present first experimental results of $\text{}^{11}$B-NMR of SmB_6 under applied pressure. From measurement of nuclear spin-lattice relaxation time $(T_1)$ we find that with applied pressure the value of activation gap $E_{g}$ is decreasing. This decrease is larger than in case of other experimental techniques. We suppose that the enhancement of $1//T_1$ in temperature range 20-100 K with applied pressure reflects not only a suppression of hybridization gap, but also changes in spin correlations.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 895-896
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:
$\text{}^{1}$H NMR Study of Molecular Dynamics of 4-apyH Cation under High Hydrostatic Pressure
Autorzy:
Medycki, W.
Świergiel, J.
Jakubas, R.
Hołderna-Natkaniec, K.
Powiązania:
https://bibliotekanauki.pl/articles/2043431.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.84.-s
76.60.-k
Opis:
Polycrystalline [4-NH$\text{}_{2}$C$\text{}_{5}$H$\text{}_{4}$NH] SbCl$\text{}_{4}$ and [4-NH$\text{}_{2}$C$\text{}_{5}$H$\text{}_{4}$NH] SbCl$\text{}_{6}$ have been investigated by proton NMR methods between 120 K and 370 K under hydrostatic pressure of 0.1 and 520 MPa. Reduction in the dipolar second moment is interpreted in terms of cation reorientation. Activation energies characterizing the motion increase with increasing pressure.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 161-164
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$\text{}^{57}$Fe Hyperfine Field Anisotropy in Ferrites and its Relation to the Non-Uniformity of the Ionic Surrounding
Autorzy:
Štepánková, H.
Englich, J.
Kohout, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013366.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.50.Gg
Opis:
The hyperfine field anisotropy tensors, obtained from analysis of $\text{}^{57}$Fe NMR spectra for iron sites in various magnetic oxides (barium hexaferrite, lithium spinel, magnetite and yttrium-iron garnet) were used to investigate the relation between the hf anisotropy and surrounding ionic arrangement. While a reasonable correlation has been found when the distribution of the nearest cations was considered, no correlation was obtained between the hyperfine field anisotropy and the positions of the nearest oxygen anions.z
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 757-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A $\text{}^{55}$Mn NMR Study of La$\text{}_{0.33}$Nd$\text{}_{0.33}$Ca$\text{}_{0.34}$Mn O$\text{}_{3}$ with $\text{}^{16}$O and $\text{}^{18}$O
Autorzy:
Rybicki, D.
Kapusta, Cz.
Riedi, P. C.
Oates, C. J.
Sikora, M.
Zając, D.
De Teresa, J. M.
Marquina, C.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2037128.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.47.Gk
Opis:
A $\text{}^{55}$Mn NMR study of $\text{}^{16}$O and $\text{}^{18}$O containing La$\text{}_{0.33}$Nd$\text{}_{0.33}$Ca$\text{}_{0.34}$Mn O$\text{}_{3}$ is reported. The spin-echo spectra measured at 4.2 K and zero field consist of a double exchange line corresponding to the ferromagnetic metallic regions. The line intensity is more than an order of magnitude lower for the $\text{}^{18}$O compound, which indicates an order of magnitude lower content of the ferromagnetic metallic phase in this compound. The frequency dependence of the spin-spin relaxation time T$\text{}_{2}$ shows a pronounced minimum at the center of the double exchange line of both compounds due to the Suhl-Nakamura interaction, which indicates that the ferromagnetic metallic regions are at least 10~nm in size. The results are discussed in terms of the influence of oxygen isotopic substitution on phase segregation.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 183-188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alkali Intercalated C$\text{}_{60}$: NMR and Magnetic Susceptibility Studies
Autorzy:
Rachdi, F.
Goze, C.
Reichenbach, J.
Lukyanchuk, J.
Kirova, N.
Zimmer, G.
Mehring, M.
Molinié, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933392.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
74.70.Wz
Opis:
We report on $\text{}^{13}$C NMR measurements on potassium intercalated C$\text{}_{60}$ compounds. By using high resolution NMR technique we were able to characterize the different thermodynamically stable phases. The effects of the intercalation on the molecular dynamics as well as on the electronic properties will be discussed. We also performed the magnetic susceptibility measurements on Rb$\text{}_{4}$C$\text{}_{60}$ compound, which reveal the activation temperature behavior with the activation energy about 1200 K. By comparison with the NMR and ESR data of the same sample we conclude that the additional electrons are localized on the C$\text{}_{60}$ molecule and form the spin singlet ground state.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 861-867
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An NMR study of Pr$\text{}_{0.5}$Ca$\text{}_{0.5}$Mn$\text{}_{1-x}$Ga$\text{}_{x}$O$\text{}_{3}$ (x=0 and 0.03)
Autorzy:
Oates, C. J.
Kapusta, Cz.
Riedi, P. C.
Sikora, M.
Zając, D.
Rybicki, D.
Martin, C.
Yaicle, C.
Maignan, A.
Powiązania:
https://bibliotekanauki.pl/articles/2037129.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.47.Gk
Opis:
An NMR study of polycrystalline Pr$\text{}_{0.5}$Ca$\text{}_{0.5}$Mn$\text{}_{1-x}$Ga$\text{}_{x}$O$\text{}_{3}$ (x=0 and 0.03) at 3 K is presented. Zero field spin-echo spectra of the Ga doped compound consist of an overlapping $\text{}^{69,71}$Ga signal at 74~MHz (hyperfine field of 5.3 T), a $\text{}^{55}$Mn double exchange line at 375 MHz (35.5 T) and a weak Mn$\text{}^{3+}$ signal between 400 and 550 MHz. Measurements in an applied field show a step-like increase in the double exchange line intensity, which corresponds to an increase in the amount of the ferromagnetic metallic phase. This coincides with a step-like feature in the bulk magnetization measurements. The effect is similar to that in the previous field dependent $\text{}^{55}$Mn NMR measurements of Pr$\text{}_{0.67}$Ca $\text{}_{0.33}$MnO$\text{}_{3}$. At the demagnetized and remanent state, a variation of spin- spin relaxation time, T$\text{}_{2}$, across the $\text{}^{55}$Mn line, due to the Suhl-Nakamura interaction is observed, which suggests that the ferromagnetic metallic double exchange regions, at liquid helium temperatures, are at least 4 nm in size.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 189-195
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antisite Defects in Epitaxial Films of Lutetium Doped Yttrium Iron Garnets Studied by Nuclear Magnetic Resonance
Autorzy:
Chlan, V.
Štěpánková, H.
Englich, J.
Řezníček, R.
Kouřil, K.
Kučera, M.
Nitsch, K.
Powiązania:
https://bibliotekanauki.pl/articles/1534129.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
76.60.-k
76.60.Lz
68.35.Dv
68.55.Ln
Opis:
Series of lutetium doped yttrium iron garnet films is studied by means of $\text{}^{57}Fe$ nuclear magnetic resonance. Satellite spectral lines are resolved and identified in the spectra and concentrations of lutetium in dodecahedral sites as well as yttrium/lutetium antisite defects in octahedral sites are estimated. Compared to yttrium, lutetium cations are found to have stronger disposition towards creating the antisite defects.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 846-847
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Hyperfine Interactions to Surface Investigations
Autorzy:
Budzyński, M.
Sarzyński, J.
Wasiewicz, R.
Powiązania:
https://bibliotekanauki.pl/articles/1929322.pdf
Data publikacji:
1993-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.35.-p
76.80.+y
76.60.-k
Opis:
In this article the principles of measurements of hyperfine interaction parameters at a given depth in a sample are presented. The advantages and the limitations of the Mössbauer spectroscopy, perturbed angular correlations and nuclear magnetic resonance are described.
Źródło:
Acta Physica Polonica A; 1993, 83, 5; 643-649
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dependence of Order and Dynamics in Polymers and Elastomers under Deformation Revealed by NMR Techniques
Autorzy:
Stapf, S.
Kariyo, S.
Powiązania:
https://bibliotekanauki.pl/articles/2043553.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Lg
82.35.Lr
76.60.-k
61.25.Hq
36.20.Ey
81.40.Lm
Opis:
Uniaxial stretching and swelling are considered as two limiting cases of deformations of elastomers. Under both conditions, the molecular dynamics is changed with respect to the behavior that describes the undisturbed, equilibrium elastomer. Particularly the spectrum of segmental motions, which reveals itself in the frequency-dependence of the longitudinal NMR relaxation time, is discussed in this study, but also order effects expressed via the dipolar coupling strength are investigated. For stretched elastomers, a significant change of the relaxation dispersion is found for three different types of rubber; it is a consequence of a change of the mode spectrum of segmental motions that becomes obvious at low frequencies (below 1 MHz at room temperature). In swollen elastomers, on the other hand, a cross-over towards a behavior expected for semi-dilute solutions is found, and a comparison to solutions of uncross-linked polymers reveals a significant effect of the cross-links only in the kHz range. A much more pronounced difference between elastomers and polymer solutions, however, is found from double-quantum encoded NMR measurements where the residual order introduced by the presence of permanent cross-links is maintained even in the presence of solvent.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 247-259
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic Disorder in Perovskites: Local Symmetry Breaking at the Sr Site in SrTiO$\text{}_{3}$
Autorzy:
Blinc, R.
Zalar, B.
Laguta, V. V.
Zidanšek, A.
Powiązania:
https://bibliotekanauki.pl/articles/2043382.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.84.Dy
76.60.-k
Opis:
A-site symmetry breaking in the macroscopically cubic paraelectric phase of SrTiO$\text{}_{3}$ was observed by quadrupole perturbed $\text{}^{87}$Sr NMR. The local symmetry breaking at the A (Sr) site is connected with slow and biased disorder dynamics similarly as at the B (Ti) site.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 7-11
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Stochastic Dynamics on the Nuclear Magnetic Resonance in a Field Gradient
Autorzy:
Tóthová, J.
Lisý, V.
Powiązania:
https://bibliotekanauki.pl/articles/1032635.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.60.Lz
05.40.-a
05.10.Gg
Opis:
In the present contribution, the attenuation function S(t) for an ensemble of spins in a magnetic-field gradient is calculated through an accumulation of the phase shifts in the rotating frame resulting from the changes of the particle displacements. The found S(t) is applicable for any kind of the stochastic motion of spins, including their non-Markovian dynamics with memory. Depending on the considered system, both the classical expressions valid for normal diffusion at long times and new formulae for the short-time Brownian motion can be obtained. Our method is also applicable to the NMR pulse sequences based on the refocusing principle. This is demonstrated by describing the spin echo experiment developed by Hahn.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1111-1113
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of the Degree of Crystallinity of Partially Crystalline Polypropylenes Using $\text{}^{13}C$ NMR
Autorzy:
Hronský, V.
Koval'aková, M.
Vrábel, P.
Uhrínová, M.
Olčák, D.
Powiązania:
https://bibliotekanauki.pl/articles/1378162.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.41.+e
76.60.-k
81.05.Lg
Opis:
The paper deals with a method for the estimation of the degree of crystallinity for partially-crystalline isotactic-polypropylenes (i-PP) using high-resolution solid-state $\text{}^{13}C$ NMR. For this purpose direct polarization $\text{}^{13}C$ MAS NMR spectra were measured for i-PP samples with different degrees of crystallinity at 98°C. The areas beneath the resonance lines in these spectra correspond to the number of carbons in particular functional groups, while the widths and shapes of the lines reflect the degree of crystallinity, crystalline modifications, distribution of chain conformations and the chain mobility. The $\text{}^{13}C$ MAS NMR spectra, measured using appropriate combination of delay time and high proton decoupling field, made it possible to detect only amorphous domains in the sample. This enabled identification of the lines associated with the amorphous domains in the complete $\text{}^{13}C$ MAS NMR spectra and provided sufficient information for reliable estimation of the degree of crystallinity. The heteronuclear Overhauser enhancement of the $\text{}^{13}C$ NMR signals due to short delay time was taken into account in our calculations.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 409-410
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Field Dependent Electron and Quadrupole Spin Relaxation: A Unified Treatment
Autorzy:
Kruk, D.
Powiązania:
https://bibliotekanauki.pl/articles/2047257.pdf
Data publikacji:
2007-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.25.+k
76.60.-k
82.56.-b
33.35.+r
76.30.-v
Opis:
This article reviews recent theoretical treatments of field dependent relaxation processes in complex systems containing mutually coupled dipolar, quadrupole, and electron spins. The presented approaches are based on an analogy between the Hamiltonian formalisms for quadrupole and zero field splitting interactions. Limitations of the presented treatments, resulting from the validity conditions of the second-order perturbation theory are discussed in detail.
Źródło:
Acta Physica Polonica A; 2007, 111, 2; 215-238
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hyperfine Field in YIG with Charged Substitution
Autorzy:
Kohout, J.
Štĕpánková, H.
Englich, J.
Novák, P.
Kučera, M.
Nitsch, K.
Powiązania:
https://bibliotekanauki.pl/articles/2013158.pdf
Data publikacji:
2000-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.50.Gg
Opis:
$\text{}^{57}$Fe NMR spectra were measured on thin films of yttrium iron garnet with divalent (Ca$\text{}^{2+}$) and tetravalent (Ge$\text{}^{4+}$) cation substitutions using the spin echo technique at 4.2 K. A series of Y$\text{}_{3-x}$Ca$\text{}_{x}$Fe$\text{}_{5-x}$Ge$\text{}_{x}$O$\text{}_{12}$ samples with 0 ≤ x ≤ 0.0 5 was prepared by an epitaxial growth from BaO/B$\text{}_{2}$O$\text{}_{3}$/BaF$\text{}_{2}$ flux on gadolinium gallium garnet substrate. Satellite lines corresponding to the iron ions having the Ge$\text{}^{4+}$ and Ca$\text{}^{2+}$ in their neighbourhood were identified. The sample with the germanium content of x(Ge) = 0.004 and (110) substrate orientation was used for a detailed study: NMR spectra of this sample were measured in an external magnetic field of 0.1 T applied along several directions in the plane of the film. The modification of the isotropic part and the anisotropy tensor of the hyperfine interaction caused by the Ge$\text{}^{4+}$ substituent were obtained from the experimental data. The results were compared with those previously reported for trivalent substitution (Ga$\text{}^{3+}$).
Źródło:
Acta Physica Polonica A; 2000, 97, 3; 519-522
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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