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Wyszukujesz frazę "61.43.Gt" wg kryterium: Temat


Tytuł:
Combined Analyses of Ion Beam Synthesized Layers in Porous Silicon
Autorzy:
Ramos, A. R.
Pászti, F.
Horváth, Z. E.
Vázsonyi, É.
Conde, O.
da Silva, M. F.
da Silva, M. R.
Soares, J. C.
Powiązania:
https://bibliotekanauki.pl/articles/2028988.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.10.-i
61.18.Bn
61.43.Gt
68.55.Ln
Opis:
High dose ion implantation was used to form polycrystalline silicide films on porous silicon with different native concentrations of light impurities (C and O). Porous silicon layers severalμm thick were implanted with 170 keV Cr$\text{}^{+}$ ions to fluences of 3×10$\text{}^{17}$ ions/cm$\text{}^{2}$ both at room temperature and 450ºC. Similar samples were implanted with 100 keV Co$\text{}^{+}$ ions to fluences of 2×10$\text{}^{17}$ ions/cm$\text{}^{2}$ at room temperature, 350ºC, and 450ºC. The formed silicide compounds were studied by Rutherford backscattering spectrometry, elastic recoil detection, glancing incidence X-ray diffraction, and four point-probe sheet resistance measurements. Selected Co implanted samples were analysed by cross-section transmission electron microscopy. Results show that the light impurities were partially expelled from the forming silicide layer. Combining cross-section transmission electron microscopy with ion beam methods it was possible to show that, in the implanted region, the porous structure collapses and densifies during implantation, but the underlying porous silicon remains intact. The layer structure, as well as the quality and type of the formed silicide, were found to depend on the original impurity level, implantation temperature, and annealing.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 773-780
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Liquation of Vycor Glasses - Study by Positron Annihilation Lifetime Method
Autorzy:
Jasińska, B.
Dawidowicz, A. L.
Radkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/2024266.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
61.43.Gt
Opis:
Two Vycor glasses of different percentages of the components were liquated between 725 K and 950 K and leached in order to produce pores. Little intermolecular voids characterized by ortho-positronium lifetime valueτ$\text{}_{2}$≈1.5 ns were observed simultaneously. At the first stage of pore formation the intensity I$\text{}_{2}$ decreased considerably for both glasses, while at liquation temperatures higher than 825 K it increased again. The increase in I$\text{}_{2}$ resulted from changes in the properties of the bulk material. The growth ofτ$\text{}_{2}$ in this range of temperatures was also observed.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 379-384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positrons and Positroniu m in Grainy and Porous Solids
Autorzy:
Kajcsos, Zs.
Liszkay, L.
Duplâtre, G.
Varga, L.
Lázár, K.
Pál-Borbély, G.
Beyer, H.
Lohonyai, L.
Caullet, P.
Patarin, J.
Powiązania:
https://bibliotekanauki.pl/articles/2025110.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
Opis:
Systematic investigations have been performed using positron annihilation techniques on micrograins of crystalline powders (e.g., MgO, Al$\text{}_{2}$O$\text{}_{3}$, SiO$\text{}_{2}$) and on various zeolites (e.g., silicalite 1, Na-X, Na-Y, ZSM-5, mordenite) aiming at a better under standing of the formation and decay of the long-lived ortho-positronium states. The techniques were lifetime spectroscopy, Doppler-effect measurements and the recording of the full energy distribution of the annihilation radiation. The influences of heat treatment, sample evacuation and presence of gases were investigated. Lifetimes over 130 ns and o-Ps fractions of about 30% were found. A strong correlation of positron annihilation technique data with a water content of the samples was evidenced. Possible pictures of the formation and decay of ortho-positronium in porous media are discussed.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 399-406
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Genetic Algorithm for Extraction of the Parameters from Powder EPR Spectra
Autorzy:
Spałek, T.
Pietrzyk, P.
Sojka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2043399.pdf
Data publikacji:
2005-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.60.Pn
02.60.Ed
76.30.Fc
82.75.Mj
61.43.Gt
Opis:
The application of the stochastic genetic algorithm in tandem with the deterministic Powell method to automated extraction of the magnetic parameters from powder EPR spectra was described. The efficiency and robustness of such hybrid approach were investigated as a function of the uncertainty range of the parameters, using simulated data sets. The discussed results demonstrate superior performance of the hybrid genetic algorithm in fitting of complex spectra in comparison to the common Monte Carlo method joint with the Powell refinement.
Źródło:
Acta Physica Polonica A; 2005, 108, 1; 95-102
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positronium Trapping in Porous Solids: Means and Limitations for Structural Studies
Autorzy:
Kajcsos, Zs.
Liszkay, L.
Duplâtre, G.
Varga, L.
Lohonyai, L.
Pászti, F.
Szilágyi, E.
Lázár, K.
Kótai, E.
Pál-Borbély, G.
Beyer, H. K.
Caullet, P.
Patarin, J.
Azenha, M. E.
Gordo, P. M.
Lopes Gil, C.
de Lima, A. P.
Ferreira Marques, M.
Powiązania:
https://bibliotekanauki.pl/articles/2042216.pdf
Data publikacji:
2005-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
78.70.Bj
61.43.Gt
Opis:
Positron annihilation techniques are used for the structural investigation of solids but the interpretation of results in grainy and porous media is still unclear. A unique picture can be obtained assuming that the dominant process is Ps trapping in competing "extended free volume" sites. In samples with a large amount of free volumes near-saturation Ps trapping will rule the lifetime pattern, and very long lifetimes of over 100 ns might arise from o-Ps trapped in mesopores. It is shown that lifetime parameters must be corrected for the 3γ/2γ counting efficiency ratio. The results demonstrate the high sensitivity of Ps to mesopores in zeolites but also that Ps-trapping poses limitations on the applicability of lifetime to structural investigation in porous systems. The evolution of the lifetime spectra upon changes in the sample and measuring conditions should be considered in a complex way, observing not only changes in some selected components but in the whole lifetime pattern simultaneously.
Źródło:
Acta Physica Polonica A; 2005, 107, 5; 729-737
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectroscopic Ellipsometry of Porphyrin Adsorbed in Porous Silicon
Autorzy:
Babonas, G.
Snitka, V.
Rodaitė, R.
Šimkienė, I.
Rėza, A.
Treideris, M.
Powiązania:
https://bibliotekanauki.pl/articles/1178739.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.68.+m
61.43.-j
61.43.Gt
Opis:
Aqueous solution of meso-tetra(4-sulfonatophenyl)porphine was deposited on electrochemically etched n-Si wafers. The morphology of the hybrid systems was investigated by scanning electron microscope and atomic force microscope techniques. The optical response of the hybrid systems was studied by spectroscopic ellipsometry in the range of 1-5 eV. Particular features in adsorption process were revealed for meso-tetra(4-sulfonatophenyl)porphine deposited on variously chemically treated Si substrates. It was found that porphyrin J-aggregates can be intercalated into large pores formed in a bulk n-Si as well as into nanopores of luminescent oxide layer.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 319-323
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Testing the Extended Tao-Eldrup Model. Silica Gels Produced with Polymer Template
Autorzy:
Śniegocka, M.
Jasińska, B.
Wawryszczuk, J.
Zaleski, R.
Deryło-Marczewska, A.
Skrzypek, I.
Powiązania:
https://bibliotekanauki.pl/articles/2043364.pdf
Data publikacji:
2005-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
61.43.Gt
Opis:
The temperature dependence of o-Ps lifetime in the pores calculated from extended Tao-Eldrup model was compared to the experimental data, collected for a set of silica gels synthesized using the polymer template technique. For the sample with average pore radii 2.0 nm rather good agreement between the model and experiment was found. For the sample with narrow pores (near 1.0 nm) the lifetime spectrum was complex. Except the range of highest temperatures the lifetimes are far from model calculations.
Źródło:
Acta Physica Polonica A; 2005, 107, 5; 868-873
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement and Analysis of the Positron Annihilation Lifetime Spectra for Mesoporous Silica
Autorzy:
Zaleski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2047164.pdf
Data publikacji:
2006-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
81.07.-b
41.75.Fr
Opis:
Positron annihilation lifetime spectroscopy as a technique of porous materials investigation is still under development. Both measurement conditions and lifetime spectra analysis methods have to be adapted to the requirements of positron porosimetry. If complex positron annihilation lifetime spectra of porous materials are processed, numerical methods of lifetime spectra analysis have to be used with a particular care. Among various methods of positron annihilation lifetime spectra analysis available, the most popular ones were tested implemented in programs MELT and LT. It was found, from the simulated spectra study, that a large number of counts in a spectrum is needed to obtain reliable results of analysis. Even then only an approximate solution is available. Determination of the approximation nature helps in a further interpretation of the results and in positron annihilation lifetime spectrometer setting adequate to the problem. For this purpose, a few complex spectra obtained from positron beam facility were tested. The results show a negligible influence of resolution function on long lifetime components, while the precise estimation of the background level is crucial. Also some distortions caused by imperfection of numerical analysis methods are pointed out.
Źródło:
Acta Physica Polonica A; 2006, 110, 5; 729-738
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation on the Crystallization Process of Eu$\text{}^{3+}$:CaSiO$\text{}_{3}$ Gel Using Optical and Thermal Methods
Autorzy:
Andrić, Ž.
Krsmanović, R.
Marinović-Cincović, M.
Dramićanin, T.
Šećerov, B.
Dramićanin, M. D.
Powiązania:
https://bibliotekanauki.pl/articles/2047860.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Gt
61.46.Hk
68.37.Hk
78.67.Bf
81.70.Pg
Opis:
Alkoxy sol-gel technique is an important preparation method for production of rare-earth based phosphors. Crystallization of gel provides a way to prepare phosphors on lower working temperatures than those required for the solid state reactions. CaSiO$\text{}_{3}$ gel samples were obtained through hydrolysis-condensation reactions of tetraethylorthosilicate as silica source. In this work we studied the process of crystallization of Eu$\text{}^{3+}$-activated CaSiO$\text{}_{3}$ gel and decomposition of organic precursors by means of thermal analysis and infrared spectroscopy. Results of scanning electron microscopy and energy-dispersion spectrometry are used to check chemical composition and morphology of synthesized material. Emission spectra and emission lifetime measurements are performed to investigate luminescence properties of Eu$\text{}^{3+}$ doped CaSiO$\text{}_{3}$ powder.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 969-974
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence of Lanthanides from Xerogels Embedded in Mesoporous Matrices
Autorzy:
Gaponenko, N.
Powiązania:
https://bibliotekanauki.pl/articles/1814047.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Fw
83.80.Jx
81.05.Rm
78.55.Mb
61.43.Gt
82.45.Cc
42.70.Qs
78.55.Ap
78.60.-b
Opis:
The report summarizes peculiarities of synthesis and luminescence properties of porous silicon, porous anodic alumina and artificial opals with the inclusions of sol-gel derived oxides (xerogels), doped with Er, Tb, and Eu. Origin of strong luminescence of lanthanides from xerogels in mesoporous matrices is discussed.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 737-749
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Thermal Investigation of Sol-Gel Derived Eu$\text{}^{3+}$:Y$\text{}_{2}$SiO$\text{}_{5}$ Nanoparticles
Autorzy:
Krsmanović, R.
Andrić, Ž.
Marinović-Cincović, M.
Zeković, I.
Dramićanin, M. D.
Powiązania:
https://bibliotekanauki.pl/articles/2047861.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Gt
61.46.Hk
68.37.Hk
78.67.Bf
81.70.Pg
Opis:
Investigation done on Y$\text{}_{2}$SiO$\text{}_{5}$ nanoparticles doped with Eu$\text{}^{3+}$ ions obtained with the alkoxy sol-gel route is presented in this paper. We investigate the optical and thermal properties of obtained material during the conversion of the gel into nanocrystalline form. Fourier transform infrared spectroscopy and fluorescence spectroscopy of Eu$\text{}^{3+}$ ions are used for the optical characterizations, while thermal analysis is done with thermogravimetric-differential thermal analysis technique. Material exhibits characteristic luminescence emission of the trivalent europium ion.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 975-980
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Carrier Heating Effect in Porous Silicon Structures Investigated by Microwaves
Autorzy:
Gradauskas, J.
Šatkovskis, E.
Česnys, A.
Stupakova, J.
Sužiedėlis, A.
Powiązania:
https://bibliotekanauki.pl/articles/1813389.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Gt
78.70.Gq
72.30.+q
Opis:
Diode-like samples, containing porous silicon structures, were investigated by microwave radiation pulses. The resistance of the samples and electromotive force arising over the samples placed in a section of waveguide was measured. Reduction of resistance of the samples was observed with increase in microwave power. More complicated shape of the electromotive force dependence on pulse power was found. It is shown that both effects could be explained by models based on a concept of carrier heating by microwave radiation.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 993-996
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron and Positronium Trapping in Heat Treated Zeolites (Ceramics), the Effect of Swift Heavy Ion Irradiation
Autorzy:
Major, P.
Kajcsos, Zs.
Liszkay, L.
Zalán, P.
Kosanović, C.
Bosnar, S.
Subotić, B.
Lázár, K.
Skuratov, V.
Havancsák, K.
Gordo, P.
Ferreira Marques, M.
Powiązania:
https://bibliotekanauki.pl/articles/1812537.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
61.43.Gt
36.10.Dr
61.80.Jh
Opis:
A systematic study of zeolite precursor gels, zeolites, and products of their recrystallization to ceramics was carried out in presence of various alkali ions. The investigation of radiation damage induced by high-energy ion beam irradiation with swift heavy ions (Bi ions at 670 MeV energy with $4×10^{12}$ ion/$cm^2$ fluence) was also included. The shortening of lifetimes found after irradiation in ceramics might probably be ascribed to interactions of o-Ps with free radicals and other quenching agents created through the ion irradiation. These lifetime-shortening interactions probably partly hide the o-Ps trapping in free volume sites.
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1441-1446
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Porosimetry Studies of Template Removal from As-Synthesized MCM-41 Silica
Autorzy:
Zaleski, R.
Wawryszczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/1812554.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
81.07.-b
Opis:
The course of template removal from MCM-41 pores was investigated by positron annihilation lifetime spectroscopy. Two methods of removal were the object of interest: a decarbonisation after standard calcination procedure and a novel procedure - pyrolysis in vacuum. The shapes of positron lifetime spectra of decarbonised sample are determined by positronium quenching caused by presence of carbon deposit on the surface. Positron annihilation lifetime spectroscopy allows also monitoring the evolution of empty space inside pores. During pyrolysis no conductive carbon is produced, so consecutive stages of template material transformation are easy to observe. In the case of pyrolysis the effect of pore emptying is obtained at temperature 500 K, lower comparing to calcination and decarbonisation (820 K).
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1543-1550
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
At the Tip of an MeV Beam: Provoking Cells and Performing Tomographic Imaging
Autorzy:
Pallon, J.
Arteaga-Marrero, N.
Nilsson, Ch.
Elfman, M.
Kristiansson, P.
Nilsson, C.
Wegdén, M.
Olsson, M.
Åkerström, B.
Powiązania:
https://bibliotekanauki.pl/articles/1808531.pdf
Data publikacji:
2009-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.79.-v
29.40.Wk
87.53.-j
87.53.Ay
25.40.Cm
29.30.Ep
29.30.Kv
61.43.Gt
Opis:
Biological applications of ion beams have recently become a new important research field using single ion hit facilities to study individual living cells and their response to the hit of a counted number of ions. One motivation is the search for a better understanding of the fundamental processes taking place in cells and organs as a result of irradiation. Another comes from the increasing interest in using high energy protons and heavy ions as a modality for radiotherapy of deep seated tumours. In the view of treatment efficiency, study of cell culture behaviour under controlled radiation experiments, and in different chemical environments at single ion hit facilities, is a first step towards a better understanding of the processes. Tomographic techniques are applicable to situations where you need information of the inside of an object but do not want to section it into thin slices or cannot do it. Using focused MeV ion beams for tomography restricts the sample size to the order of 10-100 μm, depending of the initial energy. On the other hand, the ability to focus at a sub-micrometer level makes ion beams well suited for analyses of small sized objects as cells, spores, etc. The scanning transmission ion microscopy mode of tomography gives the mass density and corresponding morphological structure of holes and pores. It can then be used to correct the results from the other mode, particle induced X-ray emission tomography. Here is discussed a porosity analysis of bentonite clay that is planned to form an important buffer zone around canisters filled with spent nuclear reactor fuel waste deposited 500 m underground in Sweden.
Źródło:
Acta Physica Polonica A; 2009, 115, 2; 501-506
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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