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Tytuł:
An Enthalpy of Solution of Cobalt and Nickel in Iron Studied with $\text{}^{57}Fe$ Mössbauer Spectroscopy
Autorzy:
Idczak, R.
Konieczny, R.
Konieczna, Ż.
Chojcan, J.
Powiązania:
https://bibliotekanauki.pl/articles/1506574.pdf
Data publikacji:
2011-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
82.60.Lf
65.40.G-
Opis:
The room temperature Mössbauer spectra of $\text{}^{57}Fe$ were measured for iron-based solid solutions $Fe_{1-x}Co_{x}$ and $Fe_{1-x}Ni_{x}$ with x in the range 0.01 ≤ x ≤ 0.05. The obtained data were analysed in terms of the binding energy $E_{b}$ between two Co or Ni atoms in the studied materials using the extended Hrynkiewicz-Królas idea. It was found that the energy is positive or the non-iron atoms interact repulsively. The extrapolated value of $E_{b}$ for x=0 was used for computation of the enthalpy of solution of cobalt and nickel in iron. The results were compared with our previous Mössbauer spectroscopy findings, the values resulting from the Miedema's model of alloys and the data derived from the enthalpy of formation of the Fe-Co and Fe-Ni systems, obtained with calorimetric methods. The comparison shows that the present results are in a qualitative agreement with the Miedema's model predictions and calorimetric measurements but they are at variance with the previous Mössbauer spectroscopy findings.
Źródło:
Acta Physica Polonica A; 2011, 119, 1; 37-40
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Atomic Force Microscopy of Instabilities and Reorganization of Langmuir-Blodgett Films
Autorzy:
Takamoto, D. Y.
Ter-Ovanesyan, E.
Schwartz, D. K.
Viswanathan, R.
Chiruvolu, S.
Zasadzinski, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/1968761.pdf
Data publikacji:
1998-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.65.Dp
Opis:
The atomic force microscope was used to show that Langmuir-Blodgett films are unstable to reorganization via a folding mechanism by which uniformly thick films spontaneously form holes and multilayer steps. These bilayer step defects originate at isolated sites and quickly spread to cover the entire film. The defects retain the sixfold symmetry of the underlying molecular lattice; after sufficient time, straight edges begin to form and the entire film is comprised of high islands with straight edges aligned with sixfold symmetry. The kinetics of the reorganization depend strongly on the chain length of the fatty acid used and the nature of the substrate. The results suggest that the reorganization is driven by an interconversion of strained, asymmetric monolayers to unstrained, centrosymmetric bilayers.
Źródło:
Acta Physica Polonica A; 1998, 93, 2; 373-382
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbonaceous Materials Obtained from Sewage Sludge for $NO_2$ Removal under Wet Conditions at Room Temperature
Autorzy:
Pietrzak, R.
Powiązania:
https://bibliotekanauki.pl/articles/1536471.pdf
Data publikacji:
2010-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
81.05.-t
81.05.Rm
82.65.+r
89.60.-k
Opis:
The effect of the processes of carbonisation and activation on adsorbents obtained from sewage sludge and their sorption properties towards $NO_2$ were studied. Carbonaceous adsorbents were obtained by carbonisation of sewage sludge at 600°C for four different times 30, 60, 90 and 120 min followed by activation of the carbonisates by $CO_2$ at 800°C for 60 min. Adsorption of $NO_2$ was carried out in wet air. It has been shown that by appropriate thermal and chemical treatment of sludge, mesoporous adsorbents capable of $NO_2$ removal can be obtained. The sorption abilities of the carbonised and activated samples to adsorb $NO_2$ have been shown to increase with increased time of carbonisation and reach maximum for the carbonisation maintained for 90 min. Further increase in this time causes a decrease in the adsorption abilities of the samples. The sorption properties of the carbonisates have been proved to be determined by the chemical character of the surface, while those of the activated samples - by the porous structure.
Źródło:
Acta Physica Polonica A; 2010, 118, 3; 487-492
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Transfer Dynamics in Atom-Metal Surface Collisions
Autorzy:
Wiertel, M.
Taranko, R.
Taranko, E.
Powiązania:
https://bibliotekanauki.pl/articles/2011189.pdf
Data publikacji:
1999-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Rf
78.70.-g
82.65.Pa
Opis:
We study the charge exchange in atom-metal collisions in the framework of the generalized time-dependent Anderson-Newns model. The electron correlations and correlated hopping are treated within the mean-field approximation. The resulting one-particle model with an effective spin-dependent atom-surface coupling is used to study the charge transfer in scattering of Na and Li atoms on metal surfaces. It is shown that the effective occupation dependent atom-surface coupling influences mainly the expectation values for producing positive, neutral, and negative particles for small work functions and high atom velocities. It is also shown that the temperature dependence of these expectation values is more visible, especially for magnetic solutions.
Źródło:
Acta Physica Polonica A; 1999, 96, 6; 769-783
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemically Modified Activated Carbons as Catalysts of Oxidative Dehydrogenation of n-Butane
Autorzy:
Malaika, A.
Wower, K.
Kozłowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1535911.pdf
Data publikacji:
2010-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Rm
81.65.Mq
81.40.Gh
82.65.+r
Opis:
Commercial availability and low price of light alkanes make them very attractive in many branches of industry. Potentially interesting is their use in the process of oxidative dehydrogenation leading to production of olefins. This study was undertaken to characterise the oxidative dehydrogenation of n-butane to 1,3-butadiene (important substrate in production of synthetic rubber and polyamides) taking place over the modified carbon catalysts obtained from peach stones precursor. The catalytic tests were performed in the temperature range 250-450°C at oxygen/n-butane ratio of 1:1. For the majority of the activated carbon samples studied at the lowest temperature the only product was $CO_2$. At 300°C the products of dehydrogenation of n-butane and side products appeared. With increasing temperature the amount of compounds generated increased and in the group of C4 hydrocarbons the dominant were 1-butene and 1,3-butadiene. The most effective catalyst was the sample oxidised with air, the least effective was the sample modified with ammonium peroxydisulphate.
Źródło:
Acta Physica Polonica A; 2010, 118, 3; 459-464
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemisorption Isotherms for Ising Anderson Hamiltonian
Autorzy:
Taranko, E.
Cardenas, R.
Taranko, R.
Fedyanin, V. K.
Powiązania:
https://bibliotekanauki.pl/articles/1931807.pdf
Data publikacji:
1994-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.45.-v
82.65.My
Opis:
The adsorption isotherms for Ising-Anderson type model Hamiltonian describing the chemisorbed system was calculated. The submonolayer coverage of the substrate surface was considered on the equal footing together with the electronic characteristics of the chemisorbed adatoms in a self-consisting manner. The resulting adsorption isotherms depend in explicit way on the electronic parameters describing the chemisorbed adatoms and substrate metal.
Źródło:
Acta Physica Polonica A; 1994, 86, 6; 917-927
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemisorption Theory at Submonolayer Coverages: Influence of the Dynamic Hopping on the Electronic Characteristics
Autorzy:
Cardenas, R.
Taranko, E.
Taranko, R.
Fedyanin, V.
Powiązania:
https://bibliotekanauki.pl/articles/1891892.pdf
Data publikacji:
1991-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.-r
82.65.My
Opis:
The influence of the dynamic hopping term included in the Newns-Anderson Hamiltonian on the electronic structure of the chemisorbed layer at different coverages rates is investigated. It is shown that this additional interaction can destroy the initial symmetry of the Newns-Anderson model or restore this symmetry in the initial negative asymmetric case. The coverage dependence of the adatom electron charge is also studied for the case of hydrogen chemisorption on a model transition metal surface.
Źródło:
Acta Physica Polonica A; 1991, 80, 5; 731-743
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Desorption Activation Energy of $SiBr_2$ Molecules according to Steady-State Approximation
Autorzy:
Knizikevičius, R.
Powiązania:
https://bibliotekanauki.pl/articles/1365355.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.65.Cf
82.20.Db
82.20.Pm
Opis:
The chemical etching of intrinsic and n-type polycrystalline silicon in $Br_2$ ambient is considered. The theoretically calculated dependences of silicon etching rates on pressure of $Br_2$ molecules at different temperatures are compared with experimentally measured ones. The reaction and desorption activation energies are evaluated. It is found that activation energy of Si + $Br_2$ → $SiBr_2$ reaction for intrinsic silicon is equal to (1.82 ± 0.24) eV, and decreases to (1.45 ± 0.24) eV when n-type silicon films are used. Desorption activation energy of $SiBr_2$ molecules for intrinsic silicon is equal to (1.94 ± 0.17) eV, and decreases to (1.51 ± 0.17) eV when n-type silicon films are used. Desorption of $SiBr_2$ molecules is an etching-rate limiting process at high pressure of $Br_2$ molecules.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1240-1243
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of an Adsorbed Atom on Resonant Charge Exchange in Atom Scattering on Metal Surfaces
Autorzy:
Taranko, R.
Taranko, E.
Wiertel, M.
Powiązania:
https://bibliotekanauki.pl/articles/2035749.pdf
Data publikacji:
2003-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.-m
82.65.+r
34.70.+e
Opis:
A simple model describing resonant charge transfer between the free-electron metal surface and an atom colliding with it at some distance from another adsorbed atom is presented. The negative ionization probability of a scattered atom is studied within the time-dependent Anderson-Newns model and the time-evolution operator approach. With appropriate models for the considered system, the ionization probability is shown to oscillate with the distance between the adsorbed atom and the collision point of the scattered atom with the metal surface. These oscillations are results of the indirect interaction between the adsorbed and the scattered atoms due to the coupling of both atoms with the metal energy band.
Źródło:
Acta Physica Polonica A; 2003, 103, 5; 483-497
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
EPR characteristics of activated carbon for hydrogen production by the thermo-catalytic decomposition of methane
Autorzy:
Więckowski, A.
Najder-Kozdrowska, L.
Rechnia, P.
Malaika, A.
Krzyżyńska, B.
Kozłowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1158900.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
33.35.+r
61.66.Hq
76.30.-v
82.30.Lp
82.65.+r
88.30.ej
Opis:
The electron paramagnetic resonance (EPR) method was used to characterize samples of activated coal before and after reactions of the catalytic decomposition of methane and ethanol at temperatures of 1023 K (750°C), 1123 K (850°C) and 1223 K (950°C). The EPR parameters: spectroscopic splitting factor g, peak-to-peak linewidth ΔBₚₚ, and spin concentration c were measured. During the ethanol-assisted catalytic decomposition of methane carbon-located-spin radicals are partially transformed into oxygen-located-spin radicals.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 701-704
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generation of Fe₃O₄ Nanoparticle Aggregates in a Ferrofluid Driven by External Electric Field
Autorzy:
Kurimský, J.
Rajňák, M.
Cimbala, R.
Paulovičová, K.
Timko, M.
Kopčanský, P.
Kolcun, M.
Kosterec, M.
Kruželák, L.
Powiązania:
https://bibliotekanauki.pl/articles/1032151.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
47.57.J-
47.65.Cb
77.22.Jp
77.22.Ch
82.70.Dd
Opis:
In the paper the experimental study of magnetic nanoparticle aggregation in a transformer oil based ferrofluid driven by an external electric field is reported. The studied ferrofluid was composed of the magnetite nanoparticles, oleic acid surfactant, and transformer oil. Generally, it is considered that superparamagnetic nanoparticles do not interact in the absence of external magnetic field. In the paper we present an experimental observation of the particle assembly formation in a direct current external electric field by optical microscopy. During the observation no external magnetic field was applied. A diluted low-polarity ferrofluid drop on a glass surface was exposed to the external static inhomogeneous electric field. It is assumed that induced dipole-dipole interaction and subsequent dielectrophoretic motion give rise to the electrohydrodynamic flow in the fluid after a certain time period. As a result, a visible particle chain was formed at the drop electrical equator. This demonstration is expected to contribute to the understanding of the streamer formation and electrical breakdown in transformer oil based ferrofluids.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 907-909
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interaction of Hydrogen with Vanadium Layers Preadsorbed on Tungsten Field Emitter Tip
Autorzy:
Błaszczyszyn, R.
Wachowicz, E.
Błaszczyszynowa, M.
Powiązania:
https://bibliotekanauki.pl/articles/1968928.pdf
Data publikacji:
1998-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.70.+q
82.65.My
Opis:
Interaction of hydrogen with vanadium layers preadsorbed on a thermally cleaned tungsten field emitter was studied at room temperature and 78 K through measurements of the total work function changes. An increase in the work function followed by its slight decrease at higher exposure can be understood taking into account the possibility of negatively (β$\text{}^{-}$) and positively (β$\text{}^{+}$) polarized adspecies formation on thin vanadium layer. This process leads to vanadium hydride formation. The work function results suggest that hydrogen diffusion into the vanadium layer is meaningful at room temperature. Thermal desorption of hydrogen adsorbate carried out within the temperature range 409-461 K from thin vanadium layer (Θ$\text{}_{V}$ = 40) provided a value of 127 ± 6 kJ/mol for the activation energy for desorption.
Źródło:
Acta Physica Polonica A; 1998, 93, 5-6; 763-773
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Negatively and Positively Polarized Hydrogen Adspecies on Thin Platinum Films
Autorzy:
Nowicka, L.
Wolfram, Z.
Duś, R.
Powiązania:
https://bibliotekanauki.pl/articles/1892305.pdf
Data publikacji:
1992-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.65.-i
73.60.Aq
Opis:
Hydrogen adsorption on thin platinum films under isothermal conditions within the temperature and pressure intervals 78-298 K and 10$\text{}^{-10}$-10$\text{}^{-2}$ Torr has been studied measuring simultaneously surface potential (SP) and pressure (P), by means of a sensitive, short response time apparatus. Two forms of hydrogen deposit of different electrical character have been distinguished. The first one arising at the beginning of adsorption decreases the surface potential, the second one following it increases the SP due to positively polarized adspecies formation. This positively polarized form is inhomogeneous as concerns binding energy. Hydrogen uptake associated with the decrease of SP becomes larger with increase of temperature. It seems that this β¯ form of the adsorbate stabilizes the positively polarized adspecies on the surface.
Źródło:
Acta Physica Polonica A; 1992, 81, 1; 117-124
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear Characterization of Safranin O Dye for Application in Optical Limiting
Autorzy:
Balaji, G.
Rekha, R.
Ramalingam, A.
Powiązania:
https://bibliotekanauki.pl/articles/1505339.pdf
Data publikacji:
2011-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Jk
42.65.-k
82.35.-x
Opis:
The optical nonlinearity of safranin O dye in methanol solution at different concentrations and as a solid film with polymethylmethacrylate (PMMA) has been studied using cw Nd-YAG laser at 532 nm as the source of excitation. The optical responses were characterized by measuring the intensity dependent refractive index $(n_2)$ of the medium using the Z-scan technique. The open aperture Z-scan trace of the dye in solution and solid sample displayed saturable absorption. The closed aperture Z-scan trace of the dye exhibited a negative (defocusing) nonlinearity. The nonlinear refractive index was found to vary with concentration. Optical limiting characteristics of the dye at various concentrations in solution were studied. The nonlinearity appears to be of thermal origin.
Źródło:
Acta Physica Polonica A; 2011, 119, 3; 359-363
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation, Characterization and Catalytic Properties of SBA-15-SO₃H Supported Tungstophosphoric Acid for Esterification Reaction
Autorzy:
Erdem, B.
Erdem, S.
Çıtak, A.
Yavru, C.
Öksüzoğlu, R.
Powiązania:
https://bibliotekanauki.pl/articles/1031202.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Gt
82.65.+r
Opis:
SBA-15-SO₃H supported tungstophosphoric acid (TPA, H₃PW₁₂O₄₀) mesoporous materials were synthesized by impregnation of TPA into the hydrothermally synthesized SBA-15-SO₃H and the catalytic performances were compared for the esterification reaction. The physical and chemical properties of the catalysts were characterized by XRD, SEM/EDX, FT-IR and N₂ adsorption/desorption techniques. The characterization results show that TPA/SBA-15-SO₃H retained the typical mesoporous structure of SBA-15-SO₃H. The experimental results indicated that TPA/SBA-15-SO₃H is a more efficient catalyst than SBA-15-SO₃H for the esterification reaction. The higher activity of TPA/SBA-15-SO₃H compared with that of SBA-15-SO₃H was consistent with the material having the low pKa value, confirming that the esterification rate was mostly dependent on the acid strength of the additional functional groups of solid acid catalyst. Accordingly, the reason for the catalytic activity difference was simply explicated by the effect of TPA, having low pKa value, affecting the pore structure and the total acidity.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 1041-1044
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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