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Tytuł:
Long-range Interactions for the A$\text{}^{3}$1$\text{}_{u}$ and B$\text{}^{3}$0$\text{}_{u}^{+}$ States of Cd$\text{}_{2}$ from Line Shape Measurements
Autorzy:
Grycuk, T.
Michalicka, M.
Rogaczewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2030719.pdf
Data publikacji:
2002-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.70.-w
34.20.-b
32.70.-n
Opis:
We report on very precise measurements of the absorption profile of the 326.1 nm resonance line of cadmium broadened by interactions with the ground state Cd atoms under thermal equilibrium. The experimental red wing profiles, corrected for the Boltzmann factor at different temperatures, are analysed in terms of the long-range potential parameters including dispersion and resonant interactions. The resonant interaction energy constant C$\text{}_{3}$ is calculated to be 2.31×10$\text{}^{-2}$ eV Å$\text{}^{3}$ and the van der Waals constant C$\text{}_{6}$ for difference potentials between the ground state X$\text{}^{1}$0$\text{}_{ }^{+}$g and the excited states B$\text{}^{3}$0$\text{}_{u}^{+}$ and A$\text{}^{3}$1$\text{}_{u}$ of Cd$\text{}_{2}$ derived experimentally are found to be (182.6± 8) eV Å$\text{}^{6}$ and (289±4) eV Å$\text{}^{6}$, respectively. The former is determined for the first time and the latter is considerably corrected in comparison to earlier determination. The van der Waals constant C$\text{}_{6}$ for the ground state of Cd$\text{}_{2}$ is discussed and estimated to be C$\text{}_{6}^{g}$=(247± 40) eV Å$\text{}^{6}$.
Źródło:
Acta Physica Polonica A; 2002, 101, 6; 825-836
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cavity Ring Down Measurement of the (1, 0) B $\text{}^{2}$Σ$\text{}_{u}^{+}$ - X $\text{}^{2}$Σ$\text{}_{g}^{+}$ Absorption Band of the N$\text{}_{2}^{+}$ Cation
Autorzy:
Fulara, J.
Łapiński, L.
Morawski, O.
Prochorow, J.
Powiązania:
https://bibliotekanauki.pl/articles/1968912.pdf
Data publikacji:
1998-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.20.Lg
39.30.+w
Opis:
The ultraviolet (1, 0) B $\text{}^{2}$Σ$\text{}_{u}^{+}$ - X $\text{}^{2}$Σ$\text{}_{g}^{+}$ transition in the N$\text{}_{2}^{+}$ cation was measured with the absorption cavity ring down technique. The N$\text{}_{2}^{+}$ cations were produced in a stationary DC discharge in nitrogen under reduced ( ≈ 0.5 Tr) pressure. The weak band due to the (4, 0) A $\text{}^{2}$Π$\text{}_{u}$ - X $\text{}^{2}$Σ$\text{}_{g}^{+}$ transition in the red part of the spectrum was also recorded. Several of the observed transitions correspond to absorptions from the vibrationally excited (ν'=1) states of N$\text{}_{2}^{+}$ and to absorptions from the neutral N$\text{}_{2}$ molecules in the triplet state.
Źródło:
Acta Physica Polonica A; 1998, 93, 5-6; 723-730
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Activated carbons from molasses as CO₂ sorbents
Autorzy:
Młodzik, J.
Sreńscek-Nazzal, J.
Narkiewicz, U.
Morawski, A.
Wróbel, R.
Michalkiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/1070546.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.U-
68.43.-h
Opis:
Aim of this research is to obtain effective, molasses based activated carbon, which would adsorb big amounts of CO₂. Molasses was mixed with KOH. Weight ratio of dry materials was 1:1 (AC1, AC3) and 1:2 (only AC2). Homogeneous mixture was obtained. Material was left for 3 h at 25°C. Drying lasted for 12 h at 200°C, and the material was grounded. The mixture was pyrolysed at 750°C, under constant flow (18 dm³/min) of nitrogen. The material was grounded again. Then, powder was washed with water, until filtrate was neutral, which took about 5 dm³ of water. AC3 was washed with 1 dm³ of water. After drying, materials were soaked in HCl (0.1 mol/dm³) for 19 h, and washed with water, until filtrate was neutral. CO₂ adsorption was performed under high pressure up to 40 atm, at 40°C. Specific surface area (according to the Brunauer-Emmett-Teller equation) was calculated for AC1, AC2 and AC3 and it is respectively 1985, 1967, and 2026 m²/g, micropore volume - 0.714, 0.707, and 0.728 cm³/g and it was between 75% and 89% of total pore volume. The excess uptake at 40 atm pressure was as follows: AC1 - 14.02 mmol/g, AC2 - 12.75 mmol/g, and AC3 - 15.79 mmol/g.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 402-404
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Boson Fields in Ordered Magnets
Autorzy:
Hoser, A.
Köbler, U.
Powiązania:
https://bibliotekanauki.pl/articles/1385608.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.30.Ds
Opis:
Spin wave theory of magnetism reveals two severe shortcomings. First, it considers non quantized classical spins and, second, the predicted temperature power functions for the thermal decrease of the magnetic order parameter hold asymptotically at T = 0 only. As experiments unambiguously show the dynamics is different for magnets with integer and half-integer spin and the "critical" power functions at T = 0 of type ΔM ≈ $T^{ε}$ or at T = $T_{c}$ of type ≈$(T_{c}-T)^β$ hold over a finite temperature range, independent of spin structure. The finite critical range unequivocally indicates that the dynamics of the spins is controlled by a field of freely propagating bosons instead by exchange interactions. Consequently, field theories are necessary for description of the thermodynamics of ordered magnets. The experimental indications will be discussed that the field quanta are essentially magnetic dipole radiation emitted by the precessing magnetic moments. Since integer and half-integer spins precess differently the generated field quanta and the dynamics of the field are correspondingly different.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 350-352
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Interaction by Exchange of Field Bosons
Autorzy:
Köbler, U.
Hoser, A.
Powiązania:
https://bibliotekanauki.pl/articles/1427529.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.30.Ds
Opis:
It is shown that atomistic spin wave theory gives no correct account of the temperature dependence of the magnetic order parameter. The experimentally observed universal temperature dependence can be explained only by a field theory of magnetism. This means that instead by interacting spins (magnons) the dynamics is controlled by a boson field. The field quanta can be supposed to be magnetic density waves with dispersions that are simple power function of wave vector. This results in the observed universality. In three dimensions the field quanta have no mass and linear dispersion and cannot be observed using inelastic neutron scattering. Experiments on standing magnetic waves in thin ferromagnetic films provide direct information on the dispersion of the field quanta. A careful analysis of the available experimental data indicates that the dispersion of the field bosons is ım q, ım $q^2,$ and ım $q^{3//2}$ in three, two, and one dimensions.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1176-1178
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
B₄C-CNT Produced by Spark Plasma Sintering
Autorzy:
Apak, B.
Sahin, F.
Powiązania:
https://bibliotekanauki.pl/articles/1401275.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
81.05.Je
81.05.U-
88.30.rh
Opis:
H.C. Starck HS Grade boron carbide (B₄C) powders with multi-walled carbon nanotube (CNT) were sintered by Spark Plasma Sintering (SPS) method in a vacuum atmosphere to obtain highly dense and fine grained final ceramic products. Powder mixtures were densified by SPS at 1650 and 1725°C using 40 MPa pressure for 5 min. The effects of heating rate, spark plasma sintering temperature and CNT additive on density, hardness, fracture toughness and microstructures of B₄C-CNT samples are investigated. Density measurements were carried out using Archimedes method. Hardness and fracture toughness were examined by Vickers indentation technique. Scanning Electron Microscope (SEM) was used to observe microstructural investigation.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1029-1031
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of H₃BO₃ on the Corrosion Properties of Ni-B Based Electroplating Coatings
Autorzy:
Karabulut, A.
Durmaz, M.
Kilinc, B.
Sen, U.
Sen, S.
Powiązania:
https://bibliotekanauki.pl/articles/1032526.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Pq
Opis:
In this study the effect of H₃BO₃ on the properties of Ni-B coating formed on the AISI 1020 steel surface produced with electroplating process was investigated. Synthesis of the coatings was done using acidic electro plating bath. Coating process was carried out within a standard cell with three electrode system using platinum as auxiliary and Ag/AgCl electrode as a reference electrode onto AISI 1020 steel substrate. Then, heat treatment was applied to coatings at 400°C during a period of 1 h. The coated samples were analyzed by optical microscope, scanning electron microscope, and X-ray diffraction. Micro hardness measurements of the coatings were realized. The study reveals that the Ni-B anti corrosion coating is amorphous in their as-plated condition and upon heat treatment at 400°C for 1 h, Ni-B coatings crystallize and produce nickel borides and nickel in the coatings. The results indicated the presence of Ni₂B, Ni₃B and Ni phases.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 147-149
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
U$\text{}_{P}$, 3U$\text{}_{P}$, 11U$\text{}_{P}$: Above-Threshold Ionization Revisited
Autorzy:
Yang, Baorui
Schafer, K. J.
Walker, B.
Kulander, K. C.
Dimauro, L. F.
Agostini, P.
Powiązania:
https://bibliotekanauki.pl/articles/1931385.pdf
Data publikacji:
1994-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.Fb
31.90.+s
32.80.Rm
Opis:
Angular distributions of very high energy photoelectrons from Xe and Kr, excited by a 50 ps, 1054 um laser, are presented. In Xe strong, narrow structures 45° off the polarization axis appear on above-threshold ionization peaks within a limited energy range centered around 9U$\text{}_{P}$, where U$\text{}_{P}$ is the intensity-dependent ponderomotive energy. Under the same conditions the effect is much weaker in krypton. These structures are discussed using a very simple classical model as well as sophisticated single active electron calculations and the Keldysh-Faisal-Reiss theory. We conclude these structures are the result of single-electron dynamics involving rescattering of a tunneling component of the continuum wave function.
Źródło:
Acta Physica Polonica A; 1994, 86, 1; 41-50
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modification of commercial activated carbons for CO₂ adsorption
Autorzy:
Sreńscek-Nazzal, J.
Narkiewicz, U.
Morawski, A.
Wróbel,A. Gęsikiewicz-Puchalska, R.
Michalkiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/1070602.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.U-
68.43.-h
Opis:
The aim of the investigations was a modification of DTO, a commercial activated carbon (AC), to improve CO₂ adsorption capacity. The adsorption of CO₂ up to 40 bar at 40°C temperature was investigated. The volumetric method was applied for CO₂ adsorption isotherm measurements. The starting material - DTO - was modified using chemical activation (KOH, ZnCl₂, K₂CO₃). The textural parameters of all the ACs were determined by nitrogen adsorption at the liquid nitrogen temperature of -196°C on Quadrasorb SI. Results showed that the AC modified with KOH had the highest S_{BET}, V_{tot}, V_{mic} values of 2063 m²/g, 1.13 cm³/g, and 0.67 cm³/g, respectively. ACs with a wider pore size distribution (from micropores to mesopores) were obtained. The maximum CO₂ adsorption was equal to 14.44 mmol/g for DTO/KOH - modified carbon whereas 8.07 mmol/g of CO₂ was adsorbed at DTO. The CO₂ adsorption capacities of the ACs were found to be closely correlated with the BET surface areas of the materials tested. The experimental data was fitted to the Freundlich, Langmuir, Sips and Toth equations to determine the model isotherm. The Sips model was found to be the best for fitting the adsorption of CO₂.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 394-401
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Transport through a Bending Contact
Autorzy:
Schröter, U.
Powiązania:
https://bibliotekanauki.pl/articles/2044664.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.23.-b
74.50.+r
74.45.+c
Opis:
The so-called "break-junction technique" allows us to realize contacts only single-atom in diameter at their thinnest point. Electronic transport through such narrow constrictions shows a quantum mechanical signature which is well described in a transport channel picture. Each individual contact is characterized by an ensemble of channel transmission probabilities. Preferred total conductance values as well as the number of channels, however, turn out to be universal for the material investigated, despite the lack of control of the exact contact geometry.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 305-310
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dimensionality in Field Theory and in Spin Wave Theory
Autorzy:
Köbler, U.
Hoser, A.
Powiązania:
https://bibliotekanauki.pl/articles/1385629.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.30.Ds
Opis:
The different meaning of dimensionality and universality in field theory and in spin wave theory is illustrated on account of experimental examples. In spin wave theory it is distinguished between the dimensionality of the spin and the dimensionality of the exchange interactions. According to Renormalization Group (RG) theory, these atomistic characteristics are unimportant for the critical dynamics. Instead by inter-atomic interactions the dynamics of the ordered state is determined by the excitations of the continuous magnetic medium. These excitations are bosons. Consequently, the dimensionality of ordered magnets has to be assessed to the dimensionality of the relevant boson field. The most serious consequence of RG theory is that the magnetic ordering transition also is executed by the boson field. Typical for boson dynamics is a finite width of the critical range. In the atomistic models universality applies asymptotically at $T_{c}$ only. It is evident that the critical power functions of the field dynamics are different from those of the atomistic dynamics.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 356-358
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation of activated carbon from beet molasses and TiO₂ as the adsorption of CO₂
Autorzy:
Glonek, K.
Sreńscek-Nazzal, J.
Narkiewicz, U.
Morawski, A.
Wróbel, R.
Michalkiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/1075525.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.U-
68.43.-h
Opis:
The objective of this work is to produce activated carbon from sugar beet molasses containing TiO₂ for CO₂ adsorption and reduction. Textural properties of activated carbons were obtained based on the adsorption-desorption isotherms of nitrogen at 77 K. The specific surface areas of activated carbons were calculated by the Brunauer-Emmett-Teller method. The volumes of micropores were obtained by density functional theory method. The adsorption isotherms of CO₂ were measured up to the pressure of 1 atm at a temperature of 40°C. The best activated carbon adsorbed 1.9 mmol/g of CO₂.
Źródło:
Acta Physica Polonica A; 2016, 129, 1; 158-161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of Fe-Nb-B Base Hardfacing of Steel
Autorzy:
Kilinc, B.
Cegil, O.
Abakay, E.
Sen, U.
Sen, S.
Powiązania:
https://bibliotekanauki.pl/articles/1311693.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.65.Kn
68.55.J-
81.65.Lp
Opis:
Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions. In the present study, three different alloy compositions of the Fe-Nb-B were used for hardfacing of the AISI 1020 steel by tungsten inert gas welding process and analyzed. The coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the range of - 45 μm particle size with different ratio. The coatings' thickness was set to 2-3 mm on the substrate. Microstructure, phase analysis and hardness of the manufactured hardfacing alloys were characterized. Deposition results indicate good quality thick coating and porosity free of the hardfacings. X-ray diffraction analyses showed that the alloyed layers include iron borides, FeNbB and iron phases. It was shown that surface alloyed layer has composite structure including steel matrix and well distributed boride phases.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 656-658
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Angle-Resolved Photoelectron Spectroscopy on CdTe(100) c(2×2)
Autorzy:
Gawlik, K.-U
Brügmann, J.
Harm, S.
Manzke, R.
Skibowski, M.
Kowalski, B.
Orłowski, B.
Powiązania:
https://bibliotekanauki.pl/articles/1929827.pdf
Data publikacji:
1993-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.At
79.60.Bm
Opis:
The CdTe(100) c(2×2) surface prepared by ion bombardment and annealing was investigated by angle-resolved photoemission spectroscopy using synchrotron radiation with photon energies between 8.5 eV and 32 eV. The bulk band structure was determined along the ΓΔX-direction normal to the surface measuring energy-distribution curves. The results are compared with a theoretical valence band structure assuming free-electron-like final states in connection with k-conservation. For further comparison we calculated the final states by the pseudopotential method and analyzed the results in form of structure plots. In this way, most of the dispersing maxima in the normal emission spectra can be explained. For this mode of photoelectron spectroscopy the resulting dispersion must be due to the component of the Bloch wave vector normal to the surface, k$\text{}_{⊥}$, keeping surface related structures at a fixed binding energy position E$\text{}_{b}$. The lack of dispersion for five structures along ΓΔX gives experimental evidence for their surface origin.
Źródło:
Acta Physica Polonica A; 1993, 84, 6; 1093-1099
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bosons and Magnons in Ordered Magnets
Autorzy:
Köbler, U.
Powiązania:
https://bibliotekanauki.pl/articles/1400556.pdf
Data publikacji:
2015-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.-b
75.30.Ds
11.10.-z
11.10.Gh
Opis:
In earlier experimental studies we have shown that in accordance with the principles of renormalization group theory the spin dynamics of ordered magnets is controlled by a boson guiding field instead by exchange interactions between nearest magnetic neighbors. In particular, thermal decrease of the magnetic order parameter is given by the heat capacity of the boson field. The typical signature of boson dynamics is that the critical power functions either at $T=T_{c}$ or at T=0 hold up to a considerable distance from critical temperature. The critical power functions of the atomistic models hold asymptotically at $T=T_{c}$ or at T=0 only. In contrast to the atomistic magnons field bosons cannot directly be observed using inelastic neutron scattering. However, for some classes of magnets the field bosons seem to have magnetic moment and thus are able to interact directly with magnons. This interaction, although weak in principle, leads to surprisingly strong functional modifications in the magnon dispersions at small q-values. In particular, the magnon excitation gap seems to be due to the magnon-boson interaction. In this communication we want to show that for small q-values the continuous part of the magnon dispersions can be fitted over a finite q-range by a power function of wave vector. The power function can be identified with the dispersion of the field bosons. It appears that for low q-values magnon dispersions get attracted by the boson dispersion and assume the dispersion of the bosons. This allows for an experimental evaluation of the boson dispersions from the known magnon dispersions. Exponent values of 1, 1.25, 1.5, and 2 have been identified. The boson dispersion relations and the associated power functions of temperature for the heat capacity of the boson fields are now empirically known for all dimensions of the field and for magnets with integer and half-integer spin quantum number. These are two 2× 3 exponent schemes.
Źródło:
Acta Physica Polonica A; 2015, 127, 6; 1694-1702
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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