Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

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

  Lista filtrów
Wyrównaj
    Wyświetlanie 1-44 z 44
    Tytuł:
    Influence of Sample Rotation on the Shape of the Free Induction Decay
    Autorzy:
    Blicharska, B.
    Kruk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929572.pdf
    Data publikacji:
    1993-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    Opis:
    Free induction decay is calculated at the presence of rotation of a liquid sample in a static magnetic field with a constant gradient.
    Źródło:
    Acta Physica Polonica A; 1993, 84, 2; 321-325
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear Spin Relaxation in Periodically Perturbed Systems IV. The Relaxation in the Presence of Double Rotation and Pulse Sequence
    Autorzy:
    Blicharski, J. S.
    Jasiński, G.
    Klose, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931829.pdf
    Data publikacji:
    1994-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    Opis:
    The effective relaxation times are calculated in the weak collision case for the system of identical nuclear spins perturbed by double rotation, periodic sequences of r.f. pulses and spin interactions.
    Źródło:
    Acta Physica Polonica A; 1994, 86, 6; 1001-1005
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear SPin Relaxation in Periodically Perturbed Systems. III. The Relaxation in the Presence of Double Rotation
    Autorzy:
    Blicharski, J.
    Jasiński, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1924283.pdf
    Data publikacji:
    1992-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    Opis:
    The effective spin relaxation times are calculated in the presence of double rotation in the weak collision case.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 6; 993-997
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear Spin Relaxation in Periodically Perturbed Systems
    Autorzy:
    Blicharski, J. S.
    Wolak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1887459.pdf
    Data publikacji:
    1991-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    Opis:
    The effective relaxation time T$\text{}_{2e}$ is calculated in the weak collision case for a system of identical nuclear spins perturbed by periodic sequences of r.f. pulses and dipole-dipole and quadrupole interactions.
    Źródło:
    Acta Physica Polonica A; 1991, 79, 4; 591-598
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear Spin Relaxation in Periodically Perturbed Systems. II. Like and Unlike Spins
    Autorzy:
    Blicharski, J. S.
    Wołak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920949.pdf
    Data publikacji:
    1992-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    Opis:
    The effective relaxation time T$\text{}_{2e}$ is calculated in the weak collision case for a system consisting of resonant nuclear spins I and nonresonant spins S, perturbed by periodic sequences of r.f. pulses and dipole-dipole interactions.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 3; 511-515
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    NMR Study of Ion Motions in [C(NH$\text{}_{2}$)$\text{}_{3}$]$\text{}_{3}$GaF$\text{}_{6}$
    Autorzy:
    Kozak, A.
    Grottel, M.
    Pająk, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1928270.pdf
    Data publikacji:
    1993-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.60.Es
    Opis:
    Proton and fluorine spin-lattice relaxation times as well as second moments were measured in guanidinium hexafluorogallate over a wide range of temperature. The analysis of all cross-relaxation effects occurring in the four unlike spin system revealed two cation motions and yielded their activation parameters. It was found that the anion size did not influence C$\text{}_{3}$ reorientation of cation nor isotropic reorientation of anion.
    Źródło:
    Acta Physica Polonica A; 1993, 83, 2; 219-225
    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:
    Molecular Dynamics in Biological Systems Observed by NMR Relaxation in a Rotating Frame
    Autorzy:
    Wierzuchowska, D.
    Skórski, L.
    Blicharska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490095.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.90.+d
    Opis:
    NMR relaxation provides powerful tools for obtaining information on three-dimensional structures, dynamic properties and intermolecular interactions of biological macromolecules. One of these methods, called dispersion profile, is based on measuring the field dependence of spin-relaxation rates in the rotating frame, $R_{1ρ} = 1//T_{1ρ}$, in the presence of a low magnetic field $B_1$. In the presented study we use this method for investigation of molecular dynamics in protein samples. Dispersion profiles can be predicted theoretically and using two models, assuming either dipolar interaction between protons or power law dispersion, we have evaluated some molecular dynamic parameters of water adsorbed on protein surface. Our researches are focused on the connections of obtained parameters of molecular dynamics with conformation changes of protein. We have calculated the correlation times and power parameters for samples of lyophilized powder of albumins (egg white and bovine and rabbit blood serum) and lysozyme, as well as its aqueous solutions. Analysis of these parameters yields valuable information on the molecular nature of investigated biological systems. We also used this method to analyze experimental data of $T_{1ρ}$ obtained by other authors for bovine serum albumin and we have found good accordance with their conclusions concerning molecular dynamics of proteins.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 434-438
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular Dynamics of Proteins Investigated by NMR Relaxation Methods
    Autorzy:
    Wierzuchowska, D.
    Blicharska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1360657.pdf
    Data publikacji:
    2014-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.90.+d
    Opis:
    The nuclear magnetic resonance relaxation times of solvent water nuclei are known to decrease upon addition of diamagnetic solute protein. For this reason NMR relaxation methods are able to provide information on molecular dynamics changes of water protons and their interaction with macromolecules' surfaces. We present results of measurements of relaxation rates $R_1$ = 1/$T_1$, $R_2$ = 1/$T_2$ and $R_{1ρ}$ = 1/$T_{1ρ}$ in the rotating frame for three proteins: chicken egg white lysozyme, egg white albumin, and bovine serum albumin, obtained at proton resonant frequency of 60 MHz. Besides the relaxation rates dependences on concentration in the 4-23% (g/100 g solution) range, the analysis of the Carr-Purcell-Meiboom-Gill CPMG multi-echo $T_2$ experiments with variable pulse rate τ was performed. The dependences of relaxation rates on protein concentration are linear at low concentration. When protein concentration increases the slope of the straight line rapidly changes at so-called "critical" concentration which depends on MW of the diluted protein. Investigated dispersion of $T_2$, obtained using the CPMG method with a variable pulse rate, for concentrations higher and lower than the "critical" one, exhibits unequal behavior. At high concentration one-exponential curves and at low concentration two-exponential curves correspond closely with experimental data. The obtained parameters of exponents allow an estimation of the ratio of the amount of water with the determined motion freedom, that is free and bounded water, in solution. We showed that the CPMG dispersion method applied to aqueous protein solutions may widen the current understanding of the nature of molecular dynamics of hydrated water protons in non-perturbed environment.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 4; 907-910
    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
    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:
    Proton and Deuteron Relaxation Study of Molecular Dynamics in Lysozyme Solutions
    Autorzy:
    Kakule, J. F.
    Węglarz, W. P.
    Shenoy, R. K.
    Sharp, A. R.
    Peemoeller, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2014096.pdf
    Data publikacji:
    2000-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    87.15.-v
    Opis:
    A nuclear magnetic resonance spin-lattice relaxation dispersion study of the relaxation of several magnetization components in both natural and deuterated lysozyme solutions was undertaken at 20°C. Proton and deuteron resonances were employed. The two-dimensional time evolution of the magnetization and the spin-spin relaxation were analyzed. In addition, an isotopic dilution study was performed at 5 and 30.6MHz. The results indicate that the water proton spin-lattice relaxation rate which arises from intermolecular relaxation between the water protons and the lysozyme protons represents a relatively strong relaxation mechanism. A model for the dynamics of the water molecules, consistent with the proton and deuteron dispersions as well as with the isotopic dilution results, is presented.
    Źródło:
    Acta Physica Polonica A; 2000, 98, 1-2; 131-152
    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:
    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:
    Relaxation of $\text{}^{53}$Cr Spin Echo Signals in Cd$\text{}_{0.985}$Ag$\text{}_{0.015}$Cr$\text{}_{2}$Se$\text{}_{4}$
    Autorzy:
    Abelyashev, G. N.
    Berzhansky, V. N.
    Polulyakh, S. N.
    Sergeev, N. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013365.pdf
    Data publikacji:
    2000-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.20.+q
    76.60.-k
    76.60.Lz
    Opis:
    The frequency dependences of the relaxation times of NMR spin echo signals of quadrupole nuclei $\text{}^{53}$Cr at t$\text{}_{e}$=τ and t$\text{}_{e}$=3τ in ferromagnetic semiconductor Cd$\text{}_{0.985}$Ag$\text{}_{0.015}$Cr$\text{}_{2}$Se$\text{}_{4}$ were investigated at temperature 4.2 K. It was shown that there are two kinds of the quadrupole nuclei $\text{}^{53}$Cr, which have quite different relaxation times. The existence of two kinds of the nuclei $\text{}^{53}$Cr was connected with doping of the cadmium selenochromite with Ag$\text{}^{+}$ ions.zap
    Źródło:
    Acta Physica Polonica A; 2000, 97, 5; 753-756
    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:
    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:
    $\text{}^{1}$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:
    Tuned Probehead for NMR Spectroscopy in Magnetically Ordered Materials
    Autorzy:
    Sedlák, B.
    Kouřil, K.
    Chlan, V.
    Řezníček, R.
    Křišťan, P.
    Pfeffer, M.
    Englich, J.
    Štěpánková, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1534619.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    07.57.Pt
    76.60.-k
    76.60.Lz
    Opis:
    This work describes the design of a tuned NMR probehead that was developed for measurement of very broad spectra in fully impedance matched mode. The probehead is constructed as an insert of continuous flow cryostat to allow operation down to helium temperatures. Properties of the probehead are demonstrated on $\text{}^{57}Fe$ NMR in magnetic oxide with spinel structure.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 924-925
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Observation of Antioxidants Activity using NMR Relaxation Measurements
    Autorzy:
    Wierzuchowska, D.
    Witek, M.
    Blicharska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030645.pdf
    Data publikacji:
    2018-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.90.+d
    76.30.Rn
    Opis:
    Formation of free radicals in biological solutions leads to the changes in water protons relaxation times. Therefore, NMR relaxation measurements were used to investigate kinetics of oxidation processes induced by the addition, in low amounts, of hydrogen peroxide (H_2O_2) to aqueous protein solution and to blood serum. The measured relaxation times were not stable over time because of the progressive formation of free radicals and their damaging action to the protein structure. The addition of antioxidants (ascorbic acid, gallic acid etc.) changed the relaxation time courses due to free radical scavenging. Similar time courses, thus anti-oxidant actions, were observed in various blood serum without antioxidant additive. Moreover, the observed kinetics of spin-lattice relaxation time (T_1) depended on several factors, such as: structure and concentration of protein solutions and activity and concentration of the added antioxidants.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 2; 289-291
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    NMR Relaxation Measurements as a Tool for Observation of Oxidative Processes
    Autorzy:
    Wierzuchowska, D.
    Skórski, L.
    Blicharska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398821.pdf
    Data publikacji:
    2016-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.90.+d
    76.30.Rn
    Opis:
    Water proton relaxation times, T₁ and T₂, were measured to assess the kinetics of the oxidative processes in biological samples. The oxidation in aqueous solutions of albumins was promoted by an addition of 3% hydrogen peroxide (H₂O₂). Immediately following this addition a sharp exponential decrease of both relaxation times was observed. As we confirmed experimentally, the time course of relaxation depended on several essential factors like structure and the concentration of proteins and also the presence of antioxidants added to solution. In experiments with protein solutions containing a small amount of ascorbic acid, after reaching a minimum, relaxation time increased towards the initial (pre-addition H₂O₂) values. We conclude that this T₁ and T₂ recovery is a consequence of the presence of antioxidants and may be used to evaluate its action. This study demonstrates that nuclear magnetic resonance (NMR) relaxation measurements may be useful in evaluating free radicals reactions and antioxidants capacity.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 2; 226-228
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Quasicritical Behaviour of the NMR and µSR Relaxation in YMn$\text{}_{2}$D$\text{}_{x}$
    Autorzy:
    Paja, A.
    Mietniowski, P.
    Figiel, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013711.pdf
    Data publikacji:
    2000-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.-s
    76.60.-k
    76.75.+i
    Opis:
    The magnetic and structural properties of YMn$\text{}_{2}$ are strongly influenced by introduction of hydrogen (deuterium) in the structure, however, it only slightly modifies the noncollinear antiferromagnetic structure of the compound. The temperature dependences of the NMR relaxation times T$\text{}_{1}$ and T$\text{}_{2}$ of deuterium and the zero-field relaxation of muons in YMn$\text{}_{2}$D$\text{}_{x}$ were measured at temperatures above the magnetic ordering temperature T$\text{}_{N}$. The corresponding relaxation rates are described by the empirical expression (T/T$\text{}_{N}$-1)$\text{}^{-η}$, where the exponent η increases linearly with deuterium concentration x. To explain this behaviour, the Moriya theory of spin fluctuations was used. The expressions for NMR and μSR relaxation rates have been calculated. The resultant formulae agree well with the experiment, giving reasonable values of fitting parameters. The results obtained are discussed in terms of spin fluctuation excitation spectrum.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 5; 867-870
    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:
    Local Magnetic and Electronic Properties of the A$\text{}_{2}$FeM'O$\text{}_{6}$ (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites
    Autorzy:
    Zając, D.
    Sikora, M.
    Prochazka, V.
    Borowiec, M.
    Stępień, J.
    Kapusta, Cz.
    Riedi, P. C.
    Marquina, C.
    De Teresa, J. M.
    Ibarra, M. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047344.pdf
    Data publikacji:
    2007-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.-m
    76.60.-k
    76.60.Jx
    78.80.En
    Opis:
    The results of a combined NMR, X-ray absorption spectroscopy and X-ray magnetic cirrcular dichroism study of the AA'FeMoO$\text{}_{6}$ and AA'FeReO$\text{}_{6}$ double perovskites are presented. They revealed a dependence of electronic and magnetic properties, including a d-electron transfer between Fe and Mo sites, on the structural tolerance factor. The maximum value of the 4d Mo electron occupation and the corresponding Mo moment is obtained for the tolerance factor of unity. This corresponds to the maximum strength of the magnetic interaction and, respectively, to the Curie temperature. The dominant T$\text{}^{5}\text{}^{/}\text{}^{2}$ type temperature dependence of the Mo hyperfine field reveals the half-metallicity of the AA'FeMoO$\text{}_{6}$ compounds. Antisite defects and antiphase boundaries have been identified in NMR measurements and the strength of their magnetic coupling have been determined. A considerable orbital contribution to the Re and Fe magnetic moments were found in the NMR and X-MCD measurements on the AA'FeReO$\text{}_{6}$ compounds. Its magnitude decreases with increasing structural tolerance factor and is correlated with their magnetic anisotropy.
    Źródło:
    Acta Physica Polonica A; 2007, 111, 6; 797-820
    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:
    NMR Study of Multiferroic Iron Niobate Perovskites
    Autorzy:
    Kouřil, K.
    Chlan, V.
    Štěpánková, H.
    Řezníček, R.
    Laguta, V.
    Raevski, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1384854.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.60.Jx
    75.10.Nr
    75.85.+t
    Opis:
    We present $\text{}^{93}Nb$, $\text{}^{207}Pb$ and $\text{}^{135,137}Ba$ NMR study of multiferroic lead iron niobate and barium iron niobate ceramics. We ascribe development of NMR spectra on cooling below room temperature to magnetism of ferric ions close to resonating nuclei and introduce a framework capable of describing key features of the observed temperature induced changes. We show that the ferric ions have much stronger influence on hyperfine fields at nuclei of large cations in lead compound and estimate strength of interaction of superantiferromagnetic clusters.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 234-236
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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:
    Structure of Iron Oxide Nanoparticles Studied by $\text{}^{57}Fe$ NMR
    Autorzy:
    Křišťan, P.
    Chlan, V.
    Štěpánková, H.
    Řezníček, R.
    Görnert, P.
    Payer, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1378149.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    75.50.Gg
    75.50.Tt
    Opis:
    In this work we apply nuclear magnetic resonance (NMR) spectroscopy of $\text{}^{57}Fe$ nuclei for investigation of submicron and nanocrystalline iron oxide systems. The studied iron oxide particles are obtained from ferrous hydroxide gels (prepared from $FeCl_{2}$ and KOH) by aging at elevated temperatures (90 °C) with $KNO_{3}$ as oxidant. The $\text{}^{57}Fe$ NMR spectra of the samples are measured in temperature range 4.2-370 K in a zero external magnetic field. Signals of $\text{}^{57}Fe$ nuclei assigned to tetrahedral and octahedral iron sites are well resolved. The NMR spectra and their temperature dependences are compared with those of stoichiometric and nonstoichiometric magnetite single crystals, as well as with samples of maghemite.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 138-139
    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:
    Solid State $\text{}^{13}C$ NMR Study of Modified Polyhydroxybutyrate
    Autorzy:
    Vrábel, P.
    Hronský, V.
    Fričová, O.
    Koval'aková, M.
    Chodák, I.
    Alexy, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1382700.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.41.+e
    76.60.-k
    81.05.Lg
    Opis:
    Structural changes in polyhydroxybutyrate (PHB) brought about by addition of chain extender and/or plasticizer were studied using $\text{}^{13}C$ MAS NMR spectra, which were measured using the direct polarization technique at 30 and 98°C. Four resonances associated with the CO, CH, $CH_{2}$ and $CH_{3}$ groups of PHB were observed in the spectra. The $CH_{3}$ resonance appearing at 98°C shows splitting into two lines related to the crystalline and amorphous regions. Analysis of the $CH_{3}$ resonances made it possible to estimate the influence of applied modifications on crystallinity and distribution of conformations in amorphous and crystalline domains of PHB samples.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 419-420
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mobile NMR for Analysis of Polyethylene Pipes
    Autorzy:
    Blümich, B.
    Casanova, F.
    Buda, A.
    Kremer, K.
    Wegener, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043383.pdf
    Data publikacji:
    2005-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Lg
    82.35.Lr
    76.60.-k
    Opis:
    NMR relaxometry is a suitable tool to determine the morphology of semi-crystalline polymers by its ability to discriminate between rigid, mostly crystalline and soft, usually amorphous material. The NMR-MOUSE$\text{}^{®}$ (nuclear magnetic resonance mobile universal surface explorer) was explored in this work to supply morphological data of poly(ethylene) pipes nondestructively. PE-100 pipes were investigated in the new state, after squeezing them flat, and after annealing well below the glass temperature. Furthermore, the change in morphology induced by a pressure load from the inside and a point load from the outside was investigated as a function of depth, and the morphology change across a welding line was imaged. A shear-band was detected by destructive high-field NMR imaging in an area of severe deformation of a pipe, where an anomalous depths profile was observed by the NMR-MOUSE. These results demonstrate that the NMR-MOUSE is a suitable tool for non-destructive state assessment of polymer pipes on the basis of laboratory reference data.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 1; 13-23
    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:
    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:
    The Free Volume of Condensed Phases Confined in a Nanopore as Seen by Computer Simulations and Compared to PALS
    Autorzy:
    Račko, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1196175.pdf
    Data publikacji:
    2014-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.70.Bj
    61.20.Ja
    76.60.-k
    64.70.pm
    Opis:
    In this contribution the free volume of glycerol phase confined in a nanopore in a wide temperature range is computed. The computed free volume is compared to the previously computed values in the glycerol bulk. The mean cavity volumes are also discussed with the experimental measurements by positronium annihilation lifetime spectroscopy. The computer simulations show that in the case of the confined glycerol phase the mean cavity volumes are larger than in the simulated bulk, and also the temperature dependence has a different qualitative behavior; the computed data are in agreement with experimental measurements performed for glycerol in a pore of comparable size with diameter 6 nm. The simulations also indicate that an aspect of filling a pore is important for experimentalists. In the case of a perfectly sealed pore the cavity volume is observed to rise with decreasing temperature.
    Źródło:
    Acta Physica Polonica A; 2014, 125, 3; 785-788
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pressure Effect on Yb-Based Strongly Correlated Electron Systems
    Autorzy:
    Mito, T.
    Otani, M.
    Nakamura, M.
    Koyama, T.
    Wada, S.
    Kotegawa, H.
    Kobayashi, T.
    Idzikowski, B.
    Reiffers, M.
    Sarrao, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810284.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.27.+a
    75.30.Kz
    75.30.Mb
    76.60.-k
    Opis:
    We studied pressure effects on $YbCu_5$ and $YbInCu_4$, good examples of the Yb-based compounds to investigate the nonmagnetic-magnetic transition in Yb-based strongly correlated electron systems. With increasing pressure, the low-temperature Fermi liquid state of $YbCu_5$ is gradually suppressed, suggesting the second-order like nonmagnetic-magnetic transition around the pressure of 5-6 GPa. On the other hand, in $YbInCu_4$ which has a pressure-induced magnetic ordered ground state above $P_C$=2.45 GPa, both high-temperature paramagnetic and low-temperature intermediate valence phases are insensitive to pressure. Our results confirm the first-order nature of the transition between the intermediate valence and magnetic ordered phases with pressure.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 47-52
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Solid State ¹³C Nuclear Magnetic Resonance Study of Morphology and Molecular Mobility in Quenched Poly(3-hydroxybutyrate)
    Autorzy:
    Baran, A.
    Vrábel, P.
    Olčák, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032243.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.41.+e
    81.05.Lg
    76.60.-k
    74.25.nj
    Opis:
    Single pulse magic angle spinning ¹³C NMR spectra and the carbon spin-lattice relaxation times T₁(¹³C) were used for the study of morphology and molecular mobility in poly(3-hydroxybutyrate) quenched in cold water after melting in a twin-screw extruder. The crystallinity of the quenched sample was found to be comparable with that of virgin material, and the decrease in dimensions of the crystallites grown after quenching was deduced from the single pulse magic angle spinning ¹³C NMR spectra. The spin-lattice relaxation curves for the carbons of the CO, CH, CH₂ and CH₃ groups were found to be bi-exponential, which enables the molecular mobility within crystalline and amorphous domains to be studied. The spin-lattice relaxation times T₁(¹³C) estimated for the carbons of the CO, CH, CH₂ groups show the chain mobility enhancement within crystalline domains of the quenched sample, but the influence of the quenching on the CH₃ group rotation and on the main chain motion within amorphous regions was not observed.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 1144-1146
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    NMR Study of (Sr,Ba,La)$\text{}_{2}$Fe$\text{}_{1+y}$Mo$\text{}_{1-y}$O$\text{}_{6}$ Double Perovskites
    Autorzy:
    Zając, D.
    Kapusta, Cz.
    Riedi, P. C.
    Sikora, M.
    Oates, C. J.
    Rybicki, D.
    De Teresa, J. M.
    Serrate, D.
    Marquina, C.
    Ibarra, M. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/2041522.pdf
    Data publikacji:
    2004-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.25.+z
    76.60.-k
    78.70.Gq
    75.47.Gk
    Opis:
    The $\text{}^{95}$Mo and $\text{}^{97}$Mo NMR spin-echo study of (Sr,Ba,La)$\text{}_{2}$Fe$\text{}_{1 +y}$Mo$\text{}_{1-y}$O$\text{}_{6}$ double perovskites is reported. Powder samples of Ba$\text{}_{1.44}$Sr$\text{}_{0.36}$La$\text{}_{0.2}$FeMoO$\text{}_{6}$ and (Ba$\text{}_{0.8}$Sr$\text{}_{0.2}$)$\text{}_{2-2x}$La$\text{}_{x}$#$\text{}_{x}$ Fe$\text{}_{1+y}$Mo$\text{}_{1-y}$O$\text{}_{6}$, where# denotes vacancies, for: x=0, y=0; x=0.1, x=0.2 and x=0.3, y=0 and y=0.2 were measured at 4.2 K and no applied magnetic field. NMR signals are observed at 55-100 MHz for the main line and 30-55 MHz for low-frequency satellite. The main line and the satellite are attributed to the ideal and defect positions of Mo atoms. La and vacancy doping introduce more defects, however, increasing the Fe/Mo ratio decreases the amount of defect Mo sites. La doping causes a satellite pattern at the high frequency side of the spectrum, which is related to different numbers of the La next neighbours. The effect is attributed to an increase in the electron density and the corresponding magnetic moment at the adjacent Mo sites and reveals a local character of the electron doping.
    Źródło:
    Acta Physica Polonica A; 2004, 106, 5; 759-765
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    SWR Studies of Higher-Order Surface Anisotropy Terms in (Ga,Mn)As Thin Films
    Autorzy:
    Puszkarski, H.
    Tomczak, P.
    Diep, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030424.pdf
    Data publikacji:
    2018-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Pp
    76.50.+g
    75.70.-i
    75.30.Ds
    76.60.-k
    Opis:
    We extend the theory of spin-wave resonance (SWR) by introducing a new formula representing the surface pinning parameter as a series of contributions from different anisotropies existing in (Ga,Mn)As thin films. Comparing our theory with the reported experimental studies of SWR in thin films of the ferromagnetic semiconductor (Ga,Mn)As, we find that besides the first-order cubic anisotropy, higher-order cubic anisotropies (in the second and third orders) as well as uniaxial anisotropies (perpendicular in the first and second orders, and in-plane diagonal) occur on the surface of this material. To our best knowledge this is the first report of the existence of higher-order surface anisotropy fields in (Ga,Mn)As thin films.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 3; 635-638
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Hyperfine Fields of Nanoperm Alloys
    Autorzy:
    Miglierini, M.
    Kohout, J.
    Lančok, A.
    Šafářová, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1428957.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Tt
    75.75.-c
    76.80.+y
    76.60.-k
    68.37.Rt
    Opis:
    Magnetic hyperfine fields of $Fe_{90}Zr_7B_3$ Nanoperm nanocrystalline alloy are characterized by $\text{}^{57}Fe$ Mössbauer spectrometry and $P^{57}Fe$ NMR as well as by magnetic force microscopy. $\text{}^{57}Fe$ NMR enables to distinguish a broad signal of iron atoms located in a residual amorphous matrix from a narrow one which belongs to Fe in nanograins. The former coincides with the distribution of hyperfine fields obtained from $\text{}^{57}Fe$ Mössbauer spectroscopy. In addition, it is possible to make a distinction between NMR signals of the Fe nanograins located in magnetic domains from that of the nanograins positioned in domain walls. This is confirmed by magnetic force microscopy where appearance of maze-domains is observed.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1263-1265
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    NMR ($\text{}^{55}$Mn, $\text{}^{139}$La) and Mössbauer Spectroscopy ($\text{}^{119}$Sn) Studies of (La$\text{}_{0.67}$Ca$\text{}_{0.33}$)(Mn$\text{}_{1-x}$Sn$\text{}_{x}$)O$\text{}_{3-δ}$ Compounds
    Autorzy:
    Przewoźnik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047327.pdf
    Data publikacji:
    2007-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    76.80.+y
    75.47.Lx
    77.80.Bh
    75.47.Gk
    Opis:
    A $\text{}^{119}$Sn Mössbauer spectroscopy and zero field $\text{}^{55}$Mn and $\text{}^{139}$La NMR studies of (La$\text{}_{0.67}$Ca$\text{}_{0.33}$)(Mn$\text{}_{1-x}$Sn$\text{}_{x}$)O$\text{}_{3-δ}$ (x=0, 0.01, 0.03, andδ≈0.06) were reported. The temperature evolution of the Sn hyperfine field (B$\text{}_{hf}$) for x=0.03 determined from the Mössbauer spectroscopy measurements was analysed within a molecular field model. A fit to the temperature dependence of B$\text{}_{hf}^{max}$ provided the Curie temperature T$\text{}_{C}^{*}$=160(3) K, which is in good agreement with T$\text{}_{C}$ obtained from dc magnetisation measurements. The $\text{}^{55}$Mn NMR spectra for $x=0$ and 0.01 show a single double exchange Mn$\text{}^{3+}\text{}^{/}\text{}^{4+}$ resonance line and exhibit strong Suhl-Nakamura relaxation effects characteristic of the ferromagnetic metallic phase. The spectra for x=0.03 show a coexistence of the double exchange line with the lines characteristic of Mn$\text{}^{3+}$ and Mn$\text{}^{4+}$ valence states. This shows that a 3% Sn doping strongly suppresses the double exchange interaction and leads to microscopic phase segregation into ferromagnetic metal and ferromagnetic insulator.
    Źródło:
    Acta Physica Polonica A; 2007, 111, 5; 649-659
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular Reorientations οf N-n-Hexyltetrachlorophthalimide Studied by $\text{}^1H$ NMR
    Autorzy:
    Hołderna-Natkaniec, K.
    Jurga, K.
    Woźniak-Braszak, A.
    Walczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1538203.pdf
    Data publikacji:
    2010-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    07.05.Tp
    31.15.E-
    33.20.Ea
    64.70.K-
    76.60.-k
    Opis:
    The spin-lattice relaxation times $T_{1}$ and the second moment of $\text{}^{1}H$ NMR line have been employed to study the internal dynamics of protons of N-n-hexyl-tetra-chloro-phthali-mides in the temperature range 80-350 K. The model of internal reorientations has been proposed.
    Źródło:
    Acta Physica Polonica A; 2010, 117, 4; 537-548
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular Dynamics in Cyclic Olefin Copolymer
    Autorzy:
    Makrocka-Rydzyk, M.
    Orozbaev, B.
    Nowaczyk, G.
    Głowinkowski, S.
    Jurga, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043644.pdf
    Data publikacji:
    2005-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    36.20.Ey
    76.60.-k
    77.22.Gm
    83.85.Vb
    82.35.Jk
    Opis:
    Nuclear magnetic resonance, broadband dielectric spectroscopy and dynamic-mechanical thermal analysis were employed to study molecular dynamics of ethylene-norbornene copolymer. The analysis of experimental data indicates existence of three motional processes denoted as αβ, andγ in order of decreasing temperature. Theα relaxation is related to the dynamic glass transition, while the β relaxation, observed only for the untreated sample, is assigned to short range segmental motions involving norbornene units. Theγ relaxation is due to very local motions of ethylene units e.g. trans-gauche isomerization, similar to those responsible forγ relaxation in polyethylene. The rate of motion accountable for γ process, follows the Vogel-Fulcher-Tammann equation, similarly to α transition, indicating cooperative nature of the motion.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 2; 385-393
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear Magnetic Resonance in Hexaferrite/Maghemite Composite Nanoparticles
    Autorzy:
    Křišťan, P.
    Hondlík, O.
    Štěpánková, H.
    Chlan, V.
    Kouřil, K.
    Řezníček, R.
    Pollert, E.
    Veverka, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1386884.pdf
    Data publikacji:
    2015-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.60.-k
    75.50.Gg
    75.50.Tt
    75.47.Lx
    61.66.Fn
    Opis:
    Due to their bio-compatibility and non-toxicity, ferrimagnetic iron oxides are suitable for various medical applications. In the case of hyperthermia, the promising approach how to reach desired magnetic properties is to combine more phases into a composite material. A series of samples containing maghemite and M-hexaferrite was prepared by sol-gel method with subsequent thermal treatment where annealing temperature and time were varied. The samples were characterized by X-ray diffraction. In this paper we focused mainly on application of nuclear magnetic resonance spectroscopy to investigate these strongly inhomogeneous nanoparticle composites. Frequency-swept ⁵⁷Fe NMR spectra of nanoparticle samples were measured in a zero external magnetic field at 4.2 K. Utilizing differences in optimal excitation field strengths and in relaxation times, we were able to resolve NMR signal assigned to hexagonal ferrite of M-phase from signal which showed features attributed to maghemite.
    Źródło:
    Acta Physica Polonica A; 2015, 127, 2; 514-516
    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
      Wyświetlanie 1-44 z 44

      Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies