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1
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Energy Levels and Spectral Lines for n=3 to n=3 Transitions in Mg-Like Tungsten Ions

100%
Hao L., Kang X.
Acta Physica Polonica A
|
2015
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vol. 128
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issue 3
274-282
EN
Energies and transitions for allowed (E1) and forbidden (E2, M1, and M2) lines for low-lying configurations in magnesium-like tungsten (W^{62+}) are studied using the multiconfiguration Dirac-Hartree-Fock approach. It is shown that the correlations within the n=3 complex, quantum electrodynamic and Breit effects are very important for the calculation of fine structure energies. The present results are compared to and agree very well with other theoretical energies, wavelengths, transition probabilities and line strengths previously published for a few lines, and are generally found to be more reliable than previous theoretical predictions. The data for E2, M1, and M2 for transitions between the levels are presented as supplemental material. Results are also compared with other theory, when available.
2
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Valence and Core-Valence Effects in N-Like Kr, Rb and Sr Ions

100%
Hao L., Feng H., Kang X.
Acta Physica Polonica A
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2015
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vol. 127
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issue 3
693-700
EN
Energy levels, wavelengths, transition rates and line strengths are reported for the 2s^22p^3-2s2p^{4} transition array in Kr(XXX), Rb(XXXI) and Sr(XXXII). Wave functions were determined using the multiconfiguration Dirac-Fock method with account for valence and core-valence correlation effects. The present results are presented and compared with experimental data and with values from other calculations. The calculated values including core-valence correlation are in good agreement with other available theoretical and experimental values, and therefore can be used for the further astrophysical investigations.
3
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Mössbauer and SQUID Characterization of Iron in Human Tissue: Case of Globus Pallidus

80%
Miglierini M., Boča R., Kopáni M., Lančok A.
Acta Physica Polonica A
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2014
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vol. 126
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issue 1
240-241
EN
Lyophilized samples of human brain tissue from the region of Globus Pallidus were investigated in powder form by ^{57}Fe Mössbauer spectroscopy and SQUID magnetometry. The obtained hyperfine parameters including isomer shift and quadrupole splitting exhibit a ferritin-like behaviour with high-spin Fe(III) sites. Three types of features were derived from temperature development of magnetic susceptibility: dominating diamagnetism, dominating paramagnetism, and intermediate states. The magnetic characteristics of the samples do not correlate with age of the donors.
4
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The Mössbauer Spectroscopy Studies οf Cementite Precipitations during Continuous Heating from As-Quenched State of High Carbon Cr-Mn-Mo Steel

80%
Krawczyk J., Bała P., Hanc A.
Acta Physica Polonica A
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2008
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vol. 114
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issue 6
1651-1657
EN
This work complements the knowledge concerning the kinetics of cementite precipitation during tempering. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The samples of investigated steel were austenitized at the temperature of 900°C and quenched in oil. Then four of five samples were tempered. Tempering consisted of heating the samples up to chosen temperatures at the heating rate of 0.05°C/s and fast cooling after reaching desired temperature. This work presents the results of investigations performed carried out using the Mössbauer spectroscopy technique and their interpretation concerning cementite nucleation and growth during tempering. The values of hyperfine magnetic field on ^{57}Fe atomic nuclei, determined for the third component of the Mössbauer spectrum as regards to its intensity, indicate that these are the components coming from ferromagnetic carbides. Big differences in hyperfine magnetic fields coming from Fe atoms existing in the structure of carbides, measured on samples heated up to the temperatures of 80°C and 210°C, in comparison with values for ^{57}Fe atoms precipitated from carbides during heating up to the temperature of 350°C and 470°C, allow to state that these are the carbides of different crystal structure. The influence of hardened steel heating temperature on cementite precipitation was determined. The Mössbauer spectroscopy was applied not only for magnetic hyperfine fileld studies, but also to analyze the values of quadrupole splitting and isomeric shift, which resulted in significant conclusions concerning the changes in cementite precipitations morphology, chemical composition and the level of stresses being present in this research.
5
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The Hyperfine Structure Calculations οf Some Excited Levels for ^{139}La I

80%
Karaçoban B., Özdemır L.
Acta Physica Polonica A
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2009
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vol. 115
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issue 5
864-872
EN
We calculated hyperfine structure constants of the 5d6s^{2}, 5d^{2}6s, 5d^{3}, 5d^{2}7s, 5d6s7s, 5d6p^{2}, 4f^{2}5d, 4f6s6p, 5d6s6p, 5d^{2}6p, 4f5d6s and 4f5d^{2} levels for ^{139}La I (Z=57). The calculations are based upon the multiconfiguration Hartree-Fock method within the framework of the Breit-Pauli relativistic corrections. Moreover, the results obtained were compared with other available calculations and experiments.
6
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The Mössbauer Spectroscopy Studies of ϵ to Cementite Carbides Transformation during Isothermal Heating from As-Quenched State οf High Carbon Tool Steel

80%
Bała P., Krawczyk J., Hanc A.
Acta Physica Polonica A
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2008
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vol. 114
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issue 6
1641-1650
EN
This work presents results of investigations using the Mössbauer spectroscopy technique and their interpretation concerning transformation of ϵ to cementite carbides during tempering in relation to the previously conducted dilatometric, microscopic and mechanical investigations. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The influence of the tempering time on nucleation and solubility of ϵ carbides, and on cementite nucleation and growth, was determined. The analysis of phase transformations during various periods of tempering using the Mössbauer spectroscopy technique made possible to reveal fine details connected with the processes.
7
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Structure and Hyperfine Interactions in Aurivillius Bi_{9}Ti_{3}Fe_{5}O_{27} Conventionally Sintered Compound

80%
Mazurek M., Lisińska-Czekaj A., Surowiec Z., Jartych E., Czekaj D.
Acta Physica Polonica A
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2011
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vol. 119
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issue 1
72-74
EN
The structure and hyperfine interactions in the Bi_{9}Ti_{3}Fe_{5}O_{27} Aurivillius compound were studied using X-ray diffraction and Mössbauer spectroscopy. Samples were prepared by the conventional solid-state sintering method at various temperatures. An X-ray diffraction analysis proved that the sintered compounds formed single phases at temperature above 993 K. Mössbauer measurements have been carried out at room and liquid nitrogen temperatures. Room-temperature Mössbauer spectrum of the Bi_{9}Ti_{3}Fe_{5}O_{27} compound confirmed its paramagnetic properties. However, low temperature measurements revealed the additional paramagnetic phase besides the antiferromagnetic one.
8
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Magnetic Behaviour of Ferritin Nanoparticles

80%
Miglierini M., Lancok A.
|
EN
Characterization of magnetic behaviour of ferritin nanoparticles of biological origin is presented. Two types of samples prepared from human and horse spleen tissues were investigated by ^{57}Fe Mössbauer spectrometry. At room temperature, ferritin nanoparticles exhibit superparamagnetic behaviour due to their small dimensions. First occurrence of magnetic interactions was noticed below 60 K. Blocking temperature of human and horse ferritin nanoparticles was determined to be of 16 K and 32 K, respectively.
9
Content available remote

Quadrupole Interactions and Anisotropic Magnetic Quenching of Positronium in Oriented Crystals

80%
Bondarev I. V., Kuten S. A.
Acta Physica Polonica A
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1995
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vol. 88
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issue 1
83-90
EN
The quadrupole interaction of positronium in noncubic defectless crystals has been investigated theoretically. It is shown to lead to the weak anisotropy of positronium magnetic quenching. The temperature dependence of the quadrupole coupling constant and the estimations of the magnitude of the anisotropy are obtained for delocalized positronium in crystalline quartz. The significant magnitude of the anisotropy is predicted for "anomalous" positronium in oriented crystalline polymeric structures.
10
Publication available in full text mode
Content available

Au-In System Studied with Perturbed Angular Correlation Method

80%
Wodniecki P., Kulińska A., Wodniecka B.
Acta Physica Polonica A
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2001
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vol. 100
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issue 5
817-822
EN
The Au-In system was the subject of our comprehensive study with the perturbed angular correlation technique. Bulk samples of all intermetallic phases shown in the phase diagram were prepared to determine the hyperfine interaction parameters and their temperature dependence. A polymorphic phase transformation in the AuIn phase at about 630 K and a new metastable modification of Au_7In_3 after quenching the sample of 30 at.% In from temperature above 700 K were found. In addition, formation of the Au-In phases of different stoichiometries at the interfaces of thin Au/In films was observed. It turned out that the starting composition of bilayer samples, i.e. the thickness ratio of the Au and In layers, strongly influenced the stoichiometry of the formed compounds.
11
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Content available

Anharmonicity and Weak Mode Assignment in La_{2-x}Sr_xCuO_4, with Oxygen Isotopic Substitution

80%
Siranidi E., Lampakis D., Palles D., Liarokapis E., Conder K.
Acta Physica Polonica A
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2007
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vol. 111
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issue 1
173-177
EN
The oxygen isotope effect on the first- and second-order Raman active modes of high-quality La_{2-x}Sr_xCu^{16,18}O_4 (80% substitution ^{16}O by ^{18}O) polycrystalline compounds with x=0.00, 0.015 was investigated at low temperatures. In the second-order Raman scattering several weak and strong peaks were observed and assigned to oxygen atom vibrations. With the isotopic substitution the apex oxygen mode follows quite well the mass harmonic law at all temperatures studied, while the soft mode is anharmonic in the temperature range of 77-180 K and for higher temperatures its anharmonicity is strongly increased. The temperature dependence of the energy of the soft mode for x=0.0 shows also a modification at≈180 K and an abnormal behaviour at≈280 K, which may be related with the transition to the antiferromagnetic phase.
12
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Content available

Mössbauer and X-ray Diffraction Studies of Zr_{1-x}Ti_xFe_2 Laves Phase Compounds

80%
Budzyński M., Sarzyński J., Surowiec Z., Wiertel M.
Acta Physica Polonica A
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2001
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vol. 100
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issue 5
717-722
EN
Mössbauer spectroscopy of ^{57}Fe and X-ray diffraction measurements in the Zr_{1-x}Ti_xFe_2 phase have been made. Our X-ray diffraction spectra revealed that the samples have the cubic C15 crystal structure for low Ti concentration and the hexagonal C14 structure for high Ti concentration. In the range of 0.2≤xࣘ0.5 a mixture of both structures occurs. The investigated compounds are paramagnetic at RT for x>0.80 and magnetic for x
13
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Structure and Hyperfine Interactions of Mechanically Activated Delafossite CuFeO₂

80%
Siedliska K., Pikula T., Oleszak D., Jartych E.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
372-375
EN
Delafossite CuFeO₂ belongs to multiferroic class of materials. In this work, copper ferrite was prepared by mechanical activation with subsequent thermal treatment. X-ray diffraction and Mössbauer spectroscopy were used as complementary methods to study the structure and hyperfine interactions of the material. As proved by X-ray diffraction, CuFeO₂ compound was obtained with relatively low amount of secondary phases like CuO and CuFe₂O₄. The Mössbauer spectroscopy revealed paramagnetic character of the compound at room temperature. The purest delafossite CuFeO₂ was obtained by mechanical activation of pre-milled precursors and sintering at 1173 K. The temperature of thermal treatment is lower by 100 K as compared to the traditional solid-state synthesis.
14
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Mössbauer Spectrometry Study of Biological Tissues

70%
Bonková I., Miglierini M., Bujdoš M., Kopáni M.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
1081-1083
EN
Magnetic microstructure of iron contained in selected biological tissues is characterized and mutually compared. We have studied three types of biological samples prepared from human brain, human and horse spleen. Original samples were lyophilized (dried in a vacuum) thus providing powder forms. As a principal method of study, ⁵⁷Fe Mössbauer spectrometry in transmission mode was used. The Mössbauer spectrometry experiments were performed at room ( ≈300 K) and at liquid helium (4.2 K) temperature. At room temperature Mössbauer spectra show doublet-like features. Such behaviour indicates possible presence of nanoparticles with fluctuating magnetic moments that acquire arbitrary positions. On the other hand, low temperature Mössbauer spectrometry measurements demonstrate significant contribution of sextets that confirmed occurrence of blocked magnetic moments of iron-containing particles. Different relative contributions of magnetic components in the low temperature spectra for the three inspected biological tissues suggest differences in the blocking temperatures of the magnetic nanoparticles present in them.
15
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Hyperfine structure operator in the tensorial form of second quantization

61%
Gaigalas G., Rudzikas Z., Scharf O.
Open Physics
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2004
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vol. 2
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issue 4
720-736
EN
The general tensorial form of the hyperfine interaction operator in the formalism of second quantization is presented. Both diagonal and off-diagnonal matrix elements of the above-mentioned operator are found using an approach based on a combination of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin) and a generalised graphical technique. This methodology allows us to account for correlation effects efficiently and, therefore, to study the hyperfine interactions in complex many-electron atoms, those with openf-shells included, in a practical manner. All this will lead us to design an efficient program for large scale calculations of hyperfine structure and isotope shift.
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