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    Wyświetlanie 1-21 z 21
    Tytuł:
    Surface Roughness by X-ray and Neutron Scattering Methods
    Autorzy:
    Sinha, S. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1945176.pdf
    Data publikacji:
    1996-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.10.Dp
    68.35.Bs
    78.20.Ci
    Opis:
    We discuss how the roughness and morphology of surfaces and interfaces can be characterized by the nondestructive techniques of X-ray and neutron scattering. We first discuss the mathematical description of rough surfaces in terms of correlation functions and then discuss the various kinds of rough surfaces which exist. These fall into the category of self-affine (Gaussian) surfaces, surfaces with capillary wave fluctuations, stepped surfaces, and surfaces with islands or pits. We then discuss how the scattering from such surfaces may be described and which types of information are available from specular reflectivity, off-specular (diffuse) scattering, and grazing incidence reflection experiments, including a comparison with results obtained by other surface techniques. We then discuss multiple rough interfaces and the scattering from thin films and multilayers. Finally, we shall discuss scattering of neutrons by magnetically rough surfaces and multilayers.
    Źródło:
    Acta Physica Polonica A; 1996, 89, 2; 219-234
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nanocrystalline Materials: Interfaces and Mesoscopic Correlations Studied by Neutron Scattering
    Autorzy:
    Stuhr, U.
    Wagner, W.
    Kohlbrecher, J.
    van Swygenhoven, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2035459.pdf
    Data publikacji:
    2002-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.46.+w
    63.22.+m
    75.20.En
    75.50.Tt
    Opis:
    Nanocrystalline materials can exhibit properties which are considerably different from their coarse-grained counterparts, making them unique for basic or applied research and also very promising for potential applications. The topics which are addressed in the present paper are magnetic properties and magnetic correlations on the nanometer scale, mechanical properties, in particular the influence of grain boundaries on the elastic and plastic behaviour, and vibration modes of grain boundary atoms in nanostructured materials.
    Źródło:
    Acta Physica Polonica A; 2002, 102, 1; 109-122
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Interlayer Coupling in EuS-Based Superlattices Deduced from Neutron Scattering Experiments
    Autorzy:
    Sankowski, P.
    Kępa, H.
    Kacman, P.
    Sipatov, A. Yu.
    Majkrzak, C. F.
    Giebultowicz, T. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2038133.pdf
    Data publikacji:
    2004-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.70.Ak
    75.25.+z
    68.65.Cd
    Opis:
    The ferromagnetic/diamagnetic semiconductor superlattices, EuS/PbS and EuS/YbSe, were studied by neutron reflectivity. In order to determine the strength of the interlayer coupling, the intensity of the first magnetic Bragg peak vs. applied external magnetic field was measured. Additionally, the in-plane anisotropy and the domain structure were studied by polarized neutron reflectivity. The dependence of the intensity of the antiferromagnetic neutron reflectivity peak vs. magnetic field was simulated using a Stoner-Wohlfarth model. To reproduce the observed spectra it was necessary to take into account the presence of fluctuations of the nonmagnetic layers thickness, by assuming a Gaussian spread of the interlayer coupling constant $J$. For both EuS/PbS and EuS/YbSe superlattices, the best fit was obtained for the directions of the in-plane easy axes, which agree with those determined by polarized neutron reflectivity.
    Źródło:
    Acta Physica Polonica A; 2004, 105, 6; 607-614
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Diffuse Neutron Scattering in the $Mn_{0.4}Cu_{0.6}$ Alloy
    Autorzy:
    Jankowska-Kisielińska, J.
    Mikke, K.
    Fijał-Kirejczyk, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813173.pdf
    Data publikacji:
    2008-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.F-
    75.30.Fv
    75.40.-s
    75.50.Lk
    Opis:
    The diffuse neutron scattering in the $Mn_{0.4}Cu_{0.6}$ alloy was measured in the temperature range 15-390K at the 3-axis neutron spectrometer at MARIA reactor in Świerk. The broad maxima of the neutron intensity were observed in the surrounding of the (0.5, 1, 0) reciprocal lattice point and other symmetry related points. The effect is similar to that observed in Mn-Cu alloys with lower Mn content at room temperature. Our results are in agreement with the earlier finding that the maxima of the short-range order incommensurate spin density wave scattering are placed at the (0.5±δ, 1, 0) reciprocal lattice point with a linear dependence of δ on the Mn concentration. In addition, some commensurate antiferromagnetic short-range order was found.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 4; 1171-1178
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inelastic Neutron Scattering in Sendust Alloy in 8-295 K Temperature Range
    Autorzy:
    Świderska, K.
    Jankowska-Kisielińska, J.
    Dobrzyński, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1419612.pdf
    Data publikacji:
    2012-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.F-
    75.30.Fv
    75.40.-s
    75.50.Lk
    Opis:
    The effects concerning magnetic and nuclear excitations in a single crystal of Sendust alloy (73.5 at.% Fe, 9.5 at.% Al, 17 at.% Si) are discussed. The excitations have been investigated by means of elastic and inelastic neutron scattering with the use of triple axis and small angle spectrometer. A few potential causes of spin wave damping in Sendust, like interactions of excitations or small-size precipitations of different compositions or directions of magnetization were disproved. It is suggested that one- and two-phonon scattering can explain observed strong increase of incoherent inelastic scattering with temperature.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 2; 400-404
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature Dependence of Magnetic Inelastic Neutron Scattering in Mn(12%Ge) Alloy
    Autorzy:
    Jankowska-Kisielińska, J.
    Mikke, K.
    Milczarek, J. J.
    Hennion, B.
    Udovenko, V. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1956523.pdf
    Data publikacji:
    1997-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Ds
    75.50.Ee
    Opis:
    A systematic study of temperature dependence of magnetic inelastic neutron scattering for itinerant antiferromagnet Mn(12%Ge) is presented. At low temperatures the experimental data are well described in terms of damped spin waves. This description becomes insufficient at least 150 K below T$\text{}_{N}$. In the temperature range 200-400 K the integrated intensity of distribution for energy transfer 13 THz increases by one third and the shape of the deconvoluted neutron scattering cross-section changes. These changes suggest that ca. 200 K below T$\text{}_{N}$ an additional contribution to the inelastic neutron scattering starts to appear and that its origin is different from spin waves.
    Źródło:
    Acta Physica Polonica A; 1997, 91, 2; 483-486
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic-Form Factor Measurements by Polarised Neutron Scattering: Application to Heavy Fermion Superconductors
    Autorzy:
    Neumann, K.-U.
    Ziebeck, K. R. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929383.pdf
    Data publikacji:
    1993-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.25.+z
    71.28.+d
    Opis:
    The experimental technique of spin polarised neutron scattering as used in magnetic form factor measurements is presented. An introduction to the interpretation and the calculation of magnetic form factors and magnetization densities is given. The experimental technique of neutron scattering theory as applied to elastic spin polarised scattering experiments is briefly introduced. The calculation of the magnetic form factor and the magnetization densities are considered for simple model systems such as a collection of localised magnetic moments or an itinerant electron system. The discussion is illustrated by an experimental investigation of the magnetic form factor in the heavy fermion superconductors UBe$\text{}_{13}$ and UPt$\text{}_{3}$. Magnetization density maps and magnetic form factors are presented, and their implications for other physical quantities are briefly discussed.
    Źródło:
    Acta Physica Polonica A; 1993, 84, 1; 43-81
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structural and Magnetic Dynamical Properties of Solids. Experimental Approach with Inelastic Neutron Scattering
    Autorzy:
    Hennion, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2011141.pdf
    Data publikacji:
    1999-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    63.20.-e
    63.20.Kr
    75.30.Ds
    75.40.Gb
    74.25.Ha
    Opis:
    Inelastic neutron scattering on single crystals is a privileged way to obtain valuable information on dynamical properties of solids. The basis of the technique is summarised. Master formulae and experimental examples for lattice dynamics and spin dynamics studies are presented.
    Źródło:
    Acta Physica Polonica A; 1999, 96, 5; 629-640
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies of Interlayer Magnetic Coupling in All-Semiconductor Superlattices by Means of Neutron Scattering Techniques
    Autorzy:
    Kępa, H.
    Giebultowicz, T. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2030768.pdf
    Data publikacji:
    2002-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.25.+z
    75.50.Pp
    75.75.+a
    Opis:
    An overview of neutron scattering studies of ferromagnetic and antiferromagnetic all-semiconductor superlattices is presented. Diffraction experiments on MnTe/CdTe, MnTe/ZnTe and EuTe/PbTe superlattices show pronounced correlations between the MnTe and EuTe layers across the non-magnetic spacers, even though these layers are antiferromagnetic and the systems are nearly-insulating. Current theory status of these systems is discussed. Diffractometry and reflectometry data from EuS/PbS superlattices reveal pronounced antiferromagnetic coupling between the ferromagnetic EuS block. First polarized neutron reflectometry data from superlattices prepared of a novel ferromagnetic"spintronics" material, Ga(Mn)As, are also presented.
    Źródło:
    Acta Physica Polonica A; 2002, 102, 1; 21-34
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Interaction of Water with Glycine: A Combined Inelastic Neutron Scattering and Raman Spectra Studies
    Autorzy:
    Zhang, P.
    Zhang, Y.
    Han, S.
    Yan, Q.
    Li, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2044762.pdf
    Data publikacji:
    2006-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    36.20.Ng
    87.64.Je
    25.40.Fq
    82.30.Rs
    Opis:
    The vibrational dynamics of water around glycine was investigated by using Raman spectroscopy and inelastic neutron scattering. Experiments of deuterated glycine versus deuterium were performed as comparison. The study shows that for glycine, the exchange of proton-deuteron on the active NH$\text{}_{3}^{+}$ side was easy, whereas there was hardly exchange on the CH$\text{}_{2}$ side. Comparing different proportion of glycine vs. water molecules we obtained that the presence of water hardly changes the main features of glycine illustrating its hydrophobic character. The intralayer hydrogen bonds of glycine crystal are difficult to be replaced due to its stronger bond than water.
    Źródło:
    Acta Physica Polonica A; 2006, 109, 3; 399-404
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inelastic Neutron Scattering in γ-Mn(12%Ge) Alloy Above and Below the Néel Temperature
    Autorzy:
    Jankowska-Kisielińska, J.
    Mikke, K.
    Hennion, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013221.pdf
    Data publikacji:
    2000-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.40.Gb
    75.30.Ds
    75.20.En
    Opis:
    The magnetic excitations different from spin waves in the γ-Mn(12%Ge) antiferromagnet are the subject of the present investigation. The inelastic neutron scattering was measured at 4 temperatures above T$\text{}_{N}$. The Lorentzian-type formula for the inelastic neutron scattering cross-section with the spectral width for a hydrodynamic region was used for data analysis. The obtained values of the "stiffness constants" are of the order of 200 meV Å and they depend weakly on temperature in the range of 1.04-1.25T$\text{}_{N}$. The inelastic neutron scattering for energy transfers below and close to the value of the gap energy of the spin wave spectrum was measured at room temperature. The observed intensities can be treated as a sum of intensities of neutrons scattered on spin waves around the magnetic Brillouin zone centre and = those scattered on fluctuations at the zone boundary.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 3; 559-562
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structure of Dilute Micellar Water Solutions of Nonionic Dimeric Surfactant Study by Small Angle Neutron Scattering Method
    Autorzy:
    Rajewska, A.
    Wilk, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1377618.pdf
    Data publikacji:
    2014-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.fg
    82.70.-y
    Opis:
    The new sugar gemini nonionic surfactant - bis(C12LA) $[(C_{56}H_{110}N_{4}O_{22})]$ was investigated by small angle neutron scattering method for six dilute solutions with concentrations: 20 CMC, 50 CMC, 75 CMC, 100 CMC, 125 CMC and 150 CMC (CMC = 7.3×$10^{-6}$ mol/$dm^{3}$, CMC = critical micellar concentration) and three temperatures (20°C, 40°C and 60°C) for the q range 0.003-0.4 $Å^{-1}$. The aim of experiment was to determine the size and shape of micelles as a function of concentration and temperature in heavy water micellar solutions of nonionic dimeric surfactant bis(C12LA).
    Źródło:
    Acta Physica Polonica A; 2014, 126, 6; 1272-1274
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dielectric Study of Pure Polymer and Mixed Monomer-Polymer Single Crystals of pTS Diacetylene: a Comparison with Neutron Scattering Results
    Autorzy:
    Longevile, S.
    Even, J.
    Bertault, M.
    Kołodziej, H. A.
    Sworakowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933586.pdf
    Data publikacji:
    1995-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    61.12.-q
    77.84.Jd
    Opis:
    Temperature and frequency dependences of the electric permittivity in mixed monomer-polymer single crystals of the diacetylene pTS (2,4-hexadiynylene bis(p-toluenesulphonate)) are reported. The dependences were determined in the temperature range 100-250 K, and in the frequency range 100 Hz - 1 MHz. Two types of single crystals were studied: nearly-fully polymerized ones, and those containing ca. 20% of polymer in the monomer matrix. The dynamics is characterized by a high-frequency response (v ≫ 3 GHz) which corresponds to the soft mode analysed previously by the Raman and neutron inelastic scatterings. At low frequencies (v ≤ 1 kHz), another component is observed, its dielectric intensity peaking around the transition temperature in the fully polymerized crystals. The results are consistent with the results obtained from NMR and neutron scattering experiments.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 2; 359-367
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inelastic Neutron Scattering Investigation of Magnetic Excitations in the Quenched and Decomposed Samples of the $Mn_{0.75}Cu_{0.25}$ Alloy
    Autorzy:
    Jankowska-Kisielińska, J.
    Świderska, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399024.pdf
    Data publikacji:
    2013-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.fm
    78.70.Nx
    75.30.Ds
    81.40.-z
    Opis:
    The influence of spinodal decomposition on the spin wave characteristics in the $Mn_{0.75}Cu_{0.25}$ alloy was studied with inelastic neutron scattering. The measurements were performed on the quenched and annealed samples at a few temperatures. Parameters of spin-wave dispersion-relation for small wave-vector were derived. The values of spin wave velocity and energy gap obtained at reduced temperature $T//T_{N}$ ≈ 0.65 are after decomposition twice higher than for the quenched sample. For the decomposed sample the values of both parameters are close to the results published for the $Mn_{0.9}Cu_{0.1}$ alloy. This fact confirms that after decomposition spin waves are present in the sample regions of Cu concentration close to 0.1 and that the neighborhood of regions with high Cu content seems not to influence them. The spin wave velocity for the quenched sample is lower than observed in any other manganese alloy.
    Źródło:
    Acta Physica Polonica A; 2013, 124, 6; 990-993
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Anisotropy of the Neutron Scattering in the Paramagnetic Phase and on the Spin Waves in the $Mn_{0.71}Ni_{0.29}$ Alloy
    Autorzy:
    Jankowska-Kisielińska, J.
    Fijał-Kirejczyk, I.
    Mikke, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810466.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.fm
    78.70.Nx
    75.30.Ds
    75.40.-s
    75.40.Gb
    Opis:
    We have confirmed the significant anisotropy of the generalised magnetic susceptibility in the paramagnetic and antiferromagnetic phase of the fcc Mn-Ni alloys. In this paper the detailed account of the experiments performed on the $Mn_{0.71}Ni_{0.29}$ alloy is given. Our main result for the paramagnetic phase is that the correlation length is larger for the direction parallel to the anisotropy axis than for the perpendicular one by a factor of 1.6. The spin-wave velocity observed at 15 K is higher for the direction parallel to the anisotropy axis than that for the perpendicular direction by a factor of 1.2. These results are similar to that for the $Mn_{0.62}Ni_{0.38}$ alloy. Our results indicate that the magnetic carriers are more localized and the magnetic interactions are less extended in alloys with higher Ni concentration.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 203-205
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Struktura a nieelastyczne rozpraszanie neutronów przez kryształy molekularne z wiązaniami wodorowymi
    Structure and inelastic neutron scattering by the molecular crystals with the hydrogen bonds
    Autorzy:
    Rok, M.
    Bator, G.
    Sobczyk, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/171492.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    kompleksy molekularne
    wiązanie wodorowe
    struktura krystaliczna
    rozpraszanie neutronów
    dynamika cząsteczek w fazie stałej
    molecular complexes
    hydrogen bonds
    crystal structure
    neutron scattering
    molecular dynamics in the solid state
    Opis:
    The molecular crystals, which are built of organic or organic-inorganic molecules, are characterized by the weak intermolecular interactions. From the viewpoint of the potential applications in electronics or optoelectronics the electric properties of the crystals are essential. In turn these properties are related to their crystal structure as well as the dynamics of the molecules in the solid state. The existence of the hydrogen bonds in the crystal structures, conventional and unconventional, is crucial from the viewpoint of the electric properties of the crystals. The dynamics of methyl groups present in the structure can be a measure of the molecular interactions in the crystals. In this work the dynamical properties, first of all taking into account the research results concerning the neutron scattering, will be discussed. The neutron technique is very effective as regards the methyl group dynamics investigations. The relationship between a formation of the conventional and unconventional hydrogen bonds and a tunneling of the methyl groups at low temperature will be discussed. The method of the interpretation of the INS spectra will be described taking into account the theoretical model, the parameters of which are fitted to the experimental data. The examples will regard the following molecular crystals: p-N,N’-1,10-tetraacethyldiaminodurene (TADD) (Figs. 2 and 4), 2,3,5,6-tetramethylpyrazine with chloranilic acid (TMP·CLA) (Figs. 5, 6 and 7), 2,3,5,6- tetramethylpyrazine with bromanilic acid (TMP·BRA) (Figs. 5 and 6) and the crystal of 3,4,7,8-tetramethylphenantroline (Me4phen) and its complex with picric acid (Me4phen·PIC) (Figs. 8 and 9). In this paper we have shown that the surrounding of the methyl group and its interactions with the adjacent molecules has a stronger effect than the changes in the electronic charge density in the molecule.
    Źródło:
    Wiadomości Chemiczne; 2017, 71, 7-8; 533-557
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Silne wiązania wodorowe w kompleksach wybranych kwasów organicznych z tetrametylopirazyną
    Strong hydrogen bonds in selected complexes of organic acids with teramethylpyrazine
    Autorzy:
    Bator, G.
    Sobczyk, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/171970.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    tetrametylopirazyna
    kwas chloranilowy
    kwas kwadratowy
    rentgenografia
    widma w podczerwieni
    widma rozpraszania neutronów
    tetramethylpyrazine
    chloranilic acid
    squaric acid
    X-ray diffraction
    infrared spectra
    neutron scattering spectra
    Opis:
    In the present review our interest is focused on the hydrogen bonded complexes of tetramethylpyrazine (TMP) with strong proton donors, in particular with chloranilic (CLA) or squaric (H2SQ) acid. The x-ray diffraction studies show that, depending on the proton donor, various assemblies with the acid are formed, e.g. the infinite O-H…N hydrogen bonded chains without proton transfer in the case of the complex with CLA. On the other hand with H2SQ the assemblies of [HSQ]2 2–-2TMPźH+ composition are created, in which the ionized HSQ–1 molecules are present in the form of dimers. These dimers are bound with the TMPźH+ cations on its both sides via the +N-H…O– hydrogen bonds. Picric acid forms with TMP the complex of the 2:1 composition with a double protonated TMP molecule. In the case of HI3 acid the interesting units of the (TMPźH+)2źTMP composition are formed, in which two TMPźH+ cations are coordinated with one TMP molecule through the +N-H…N bridges. In the infrared spectra of the TMP complexes, both with CLA and H2SQ, the similar absorption continua are observed. They can be interpreted in terms of an asymmetric potential for the proton motion, with either the double minimum or the single broad minimum potential for the CLA and H2SQ complexes, respectively. An analysis of the neutron scattering spectra concerns the phenomena of the tunneling splitting, quasielastic neutron scattering (QNS) and inelastic (INS) scattering. In the case of tunneling splitting neat TMP does not show any tunneling transitions in the ěeV energy region, because they are overlapped by the elastic scattering band. In the case of the TMPźCLA complex four tunneling transitions are seen corresponding to the four crystallographically nonequivalent CH3 groups in the TMP molecule. In the spectrum of the complex with squaric acid the observed two transitions are ascribed to the two different CH3 groups. The two remaining CH3 group tunneling transitions are overlapped by the elastic scattering. The measurements in various low temperature ranges yield information about the shape of the CH3 group rotational potential. The shape of the potential is also reflected in the spectra of quasielastic scattering. In particular the temperature dependence of the quasielastic band allows us to find the activation energy for the CH3 rotations. Finally the inelastic neutron scattering spectra are analyzed in the energy range of the CH3 torsional modes (below 200 cm–1 = 25 meV). The analysis shows that for the complexes the torsional vibration frequencies are markedly lower than those for neat TMP. In the case of the TMPźCLA complex frequencies found are particularly low. They are close to the frequencies calculated for the TMP+ cation. A general conclusion can be drawn that in the complexes the CH3 groups behave more loosely than in neat TMP.
    Źródło:
    Wiadomości Chemiczne; 2011, 65, 9-10; 869-885
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Neutron and X-Ray Scattering in the Studies of Metals
    Autorzy:
    Dobrzyński, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/2011013.pdf
    Data publikacji:
    1999-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    71.55.Ak
    25.40.Dn
    41.60.Ap
    Opis:
    Neutrons and X-rays are well established tools for studying properties of condensed matter. With the advent of synchrotron radiation facilities their high photon fluxes started to be effectively used in the fields reserved earlier for neutrons. Although the two techniques are conceptually so similar that many physical problems can be solved using either technique, there are apparent fields in which one method is superior with respect to the other one. Therefore both techniques are often needed for characterization of the material of interest. The paper concentrates on the studies of some static properties of metals and alloys. Relatively wide range of phenomena is presented, starting from structural aspects and ending on the sophisticated studies of the magnetic moment components. The paper is intended to bring a short (yet necessarily subjective and incomplete) review of what has recently been achieved by using neutrons and X-rays in metal (or more precisely - metallic states) studies.
    Źródło:
    Acta Physica Polonica A; 1999, 96, 2; 165-180
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Scattering of Neutron in the Magnetic Field οf 180° Bloch Wall
    Autorzy:
    Sazonov, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1538632.pdf
    Data publikacji:
    2010-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    03.65.Nk
    03.75.Be
    75.60.Ch
    02.30.Gp
    Opis:
    The exact solution of the Pauli equation has been derived for neutron wave propagating in magnetized continuum containing the magnetization non-uniformity such as the 180° Bloch wall, whose structure corresponds to the Landau-Lifshitz model. The scattering coefficients with and without neutron spin flip are presented as functions of ratio of neutron energy to the media's magnetic induction value. The possibility of narrow (≲100 Å) domain wall width measurement is discussed by the example of $YFe_{11}Ti$ alloy.
    Źródło:
    Acta Physica Polonica A; 2010, 117, 3; 449-453
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fast Neutron Activation Analysis of gold by inelastic scattering, 197Au(n,ngamma)197Aum, by means of Plasma Focus device
    Autorzy:
    Verri, G.
    Mezzetti, F.
    Da Re, A.
    Rapezzi, L.
    Gribkov, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/146754.pdf
    Data publikacji:
    2000
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    activation
    gold
    neutron
    plasma focus
    Opis:
    The application of a Fast Neutron Activation Analysis (FNAA) technique on samples of pure gold, irradiated by a plasma focus of 7 kJ, has been investigated. The reaction was the inelastic scattering of neutrons, 197Au(n,n'gamma)197Aum. To avoid problems connected with peculiar features of the neutron emission from this kind of source, a preliminary standardisation of the method has been carried out. The results obtained have a practical interest in view of possible applications to the technology of extraction of minerals.
    Źródło:
    Nukleonika; 2000, 45, 3; 189-191
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An internal standard for Fast Neutron Activation Analysis spectra obtained by means of Plasma Focus devices
    Autorzy:
    Verri, G.
    Tartari, A.
    Rapezzi, L.
    Mezzetti, F.
    Gribkov, V. A.
    Da Re, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147122.pdf
    Data publikacji:
    2001
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    gold
    inelastic scattering
    lead
    mineral resources
    NAA
    plasma focus
    Opis:
    The behaviour of Pb activation peaks, which appear in an X-ray spectrum of Fast Neutron Activation Analysis (FNAA) performed by means of a Plasma Focus (PF) neutron source and an NaI scintillator counter, has been studied. The PF device generates neutron bursts of different intensities. To know the exact neutron flux illuminating a sample during PF discharges an external neutron counter is usually used. The nature and behaviour of the indicated peaks suggest that one could use one of them as an internal standard for neutron production measurement instead of an external counter. This technique allows more reliable and accurate determinations of the presence of various elements.
    Źródło:
    Nukleonika; 2001, 46, suppl. 1; 103-105
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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