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AbstractAbstract
[en] New data about antiprotons in gaseous targets at very low pressure collected by the OBELIX apparatus at LEAR show significant differences between H2 and D2; the right way to explain these differences seems to be through a nuclear stopping power as confirmed by Monte Carlo simulations
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3. international conference on nucleon-antinucleon physics; Materialy tret'ej mezhdunarodnoj konferentsii po nuklon-antinuklonnoj fizike; Moscow (Russian Federation); 11-16 Sep 1995; 18 refs.
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[en] The interpretation of the measurements of the integrated electron content in terms of gravity wave requires (1) a gravity wave model at thermospheric altitudes; (2) a gravity wave-ionization interaction model in the F-region of the ionosphere; and (3) a computing program for the resulting perturbation on the integrated electron content between the satellite and the earth station used. The gravity wave model considered in this paper takes into account the dissipative effects (viscosity, thermal conduction) which become very importanr above 250 km altitude and the effect of the base wind which is capable of affecting deeply the propagation of the waves of medium scale. Starting with this model, the domains of frequencies and the wavelength of atmospheric waves which may exist in the upper atmosphere are considered. The interaction of such waves and the ionization is examined. The theoretical results give information particularly on the selectivity of the ionospheric response to the wave passage. The deduced selectivity of the models appears to be smaller than that given by other authors who used simplified gravity wave models. The method for computing the perturbation of the of the integrated electron content introduced by the wave passage is given for a geostationary satellite. Computational results are presented for application to the case of medium scale gravity waves. (author)
Original Title
De la mesure du contenu electronique integre appliquee a l'observation des ondes de gravite de moyenne echelle
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Journal of Atmospheric and Terrestrial Physics; v. 38(3); p. 261-270
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[en] Raman spectroscopy has been applied to study zirconium hydrolysis in aqueous solution as a function of the metal concentration and of the number of OH- and H+ ions added. Careful resolution of the Raman bands, recorded in the frequency range from 300 to 650 cm-1, have been performed in order to calculate the proportions of the five aquo-hydroxo and oxo-complexes previously identified. Such calculations have been carried out by selecting the most intense and specific Raman band which characterize each of the five complexes. This Raman band can be featured by a scattering coefficient kx given by: I = kx[X], where I is the maximum intensity of the band and [X] is the concentration of the complex considered. Scattering coefficients are computed step by step from Raman spectra recorded on solutions where one of the five complexes is predominent. It allows to calculate the proportions of the different species at any step of the hydrolysis. Such proportions have been found to vary noticeably by aging of the zirconium aqueous solutions
[fr]
La spectroscopie Raman a ete utilisee pour etudier l'hydrolyse du zirconium en solution aqueuse en fonction de la concentration du metal et du nombre d'ions H+ et OH- ajoutes. Les calculs ont ete effectues en selectionnant la bande Raman la plus intense et la plus specifique, caracterisant chacun des 5 complexes. A ces bandes sont associes des coefficients de diffusion, donnes par I = kx [X] avec [X] la concentration du complexe et I le maximum d'intensite de la bande. Ces coefficients de diffusion sont calcules point par point a partir de spectres enregistres sur des solutions ou l'un des 5 complexes predomine. Ils permettent de calculer les proportions des differentes especes presentes a chaque stade d'hydrolyse. Ces proportions varient avec le vieillissement des solutionsOriginal Title
Etude de l'hydrolyse de Zr(IV) par spectrometrie Raman et RMN du proton. II. Influence de l'acidite et du vieillissement des solutions sur les proportions des especes formees
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[en] Zr (IV) hydrolysis is studied on zirconium oxide chloride in aqueous solutions, in terms of metal concentration and number of OH- and H+ ions added. Four main steps are identified. In concentrated solutions, NMR confirms that the major complex is the tetramer [Zr4 (OH)8 (H2O)16]8+, containing double bridging hydroxide groups. Addition of OH- ions leads to a progressive breakage of such double-bridges which are replaced by simple oxo bridges in agreement with the weak isotopic shift of some Raman bands observed by deuteriation. Raman spectra of the last step of hydrolysis preceding the complete precipitation of hydrated zirconia is consistent with the presence of several zirconium complexes in which -Zr-O-Zr- chains are ended by OH groups. Addition of concentrated HCl to zirconium oxide chloride solutions leads very likely to one or several monomeric species
[fr]
L'hydrolyse du Zr (IV) est etudiee sur des solutions aqueuses d'oxychlorure de zirconium en fonction du nombre d'ions OH- ou H+ ajoutes et de la concentration en metal. Quatre etapes principales sont ainsi identifiees. En solution concentree la RMN confirme que l'espece majoritaire est le tetramere [Zr4 (OH)8 (H2O)16]8+ qui contient des doubles ponts hydroxo entre atomes de zirconium. Par addition d'ions OH-, ces doubles ponts se rompent progressivement pour donner des simples ponts oxo, comme le prouve, a cette etape, le faible deplacement de certaines bandes Raman pour les solutions deuteriees correspondantes. Le dernier stade de l'hydrolyse avant la precipitation complete de zircone hydratee est constitue par une ou plusieurs especes, de meme type, comportant des groupements OH terminaux, fixes sur les atomes de zirconium lies entre eux par des ponts oxo. En milieu acide chlorhydrique concentre le tetramere conduit a une ou plusieurs especes monomeresOriginal Title
Etude de l'hydrolyse de Zr(IV) par spectrometrie Raman et RMN du proton. I. Mise en evidence et formulation des especes en solution
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Malliavin, M.-J.; Acher, O.; Bertin, F.; Larin, V.S., E-mail: maliavin@ripault.cea.fr2000
AbstractAbstract
[en] We investigate the permeability of thin amorphous glass-covered Co-based wires up to GHz frequencies. The measured permeability μparallel parallel to the direction of the wires can be estimated by the Landau-Lifschitz equation. When an external field is applied, the resonance frequency varies which may be the result of the inhomogeneity of the anisotropy field inside the microwire
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S0304885300002948; Copyright (c) 2000 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Journal of Magnetism and Magnetic Materials; ISSN 0304-8853; ; CODEN JMMMDC; v. 215-216(3); p. 811-812
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[en] Interests in infrared spectroscopy (IRS) have been stimulated by the increasing need for non-destructive surface characterization providing structural and chemical informations about the new materials used in microelectronic devices. Standard infrared spectroscopy of thin layers is limited because of its lack of sensitivity. The use of optical configurations such as the attenuated total reflection (ATR) allows to characterize nanometric layers. This paper will present the results of a study conducted for a better understanding of the capabilities and limitations of this technique. A theoretical analysis based on a perturbation method is used to elucidate the results of ATR measurements performed on silicon oxide layers of different thickness on silicon substrates. This analysis shows that the absorbance ATR spectrum in p polarization is the image of the layer energy loss function, under specific conditions. The exact ATR spectrum simulation using a matrix formalism showed that the straightforward interpretation in terms of the layer dielectric function is limited to a very narrow layer thickness range. The fitting process of the ATR spectrum is evaluated for the interpretation of experimental spectra obtained for the growth of chemical silicon oxide layers
Source
E-MRS 2002 Symposium E: Advanced characterisation of semiconductors; Strasbourg (France); 18-21 Jun 2002; S0921510702007493; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Materials Science and Engineering. B, Solid-State Materials for Advanced Technology; ISSN 0921-5107; ; CODEN MSBTEK; v. 102(1-3); p. 16-21
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[en] Attenuated total reflection (ATR) spectroscopy and spectroscopic ellipsometry (SE) have been used to characterize oxides used for the scanning capacitance microscopy (SCM) technique. SCM has been used to study boron and phosphorous doped Si test structures epitaxially grown on (100) Si substrates. SCM samples have one-dimensional (1D) doping profiles with sub-micron features, with staircase-like steps in the unipolar sample and a smoother profile in the bipolar sample, as obtained by secondary ion mass spectrometry (SIMS) profiling. Cross-sectional SCM results obtained on samples oxidized by the standard low-temperature UV-ozone method are presented, discussed and compared to results obtained on cleaved samples oxidized by a simple exposure to air. The results show that the native oxide covering a (110) cleaved section may yield SCM images of sufficient quality, with no contrast reversal on a wide range of doping levels, as well as observed on sections prepared with the UV-ozone technique. However, the long-term stability of the SCM signal on native oxides is poor, and UV-ozone oxidation can be used to recover a valid SCM signal. Realistic ultrathin oxide thickness data obtained by SE on (110) substrates are presented together with ATR results, which confirm the superior quality of UV-ozone oxides with respect to other kinds of oxides
Source
E-MRS 2002 Symposium E: Advanced characterisation of semiconductors; Strasbourg (France); 18-21 Jun 2002; S0921510703000151; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
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Materials Science and Engineering. B, Solid-State Materials for Advanced Technology; ISSN 0921-5107; ; CODEN MSBTEK; v. 102(1-3); p. 113-118
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AbstractAbstract
[en] Calculation of malonic acid formation constants was carried out from the modification of relative intensities of certain Raman bands belonging to the following species: CH2(C00H)2, HOCO-CH2-C00- and CH2(C00)2-, in terms of pH. A similar study performed on CH2(C00H)2-Be2+ system shows the high efficiency of Raman spectroscopy in the determination of stability constants for equilibria in aqueous solution. 10 refs
[fr]
L'evolution en fonction du pH des intensites relatives de certaines bandes Raman caracterisant les especes: CH2(C00H)2, H00CCH2C00 et CH2(C00)2-2 a permis de calculer les constantes de formation de l'acide malonique. Une etude similaire effectuee sur le systeme CH2(C00H)2-Be2+ a montre le grand avantage de la spectrometrie Raman pour la determination des constantes de stabilite des equilibres chimiques en solutionOriginal Title
Determination des constantes de stabilite des acides malonique et malonatoberyllate en solution aqueuse par spectrometrie Raman
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[en] Voltammetric study of the neutralization of an aqueous solution of zirconium oxychloride, ZrOCl2.8H2O, by sodium hydroxide reveals pH jumps for the following hydrolysis ratios: r=1.3-1.7-2 and 2.5. The first two agree with the formation of gelatinous precipitates, the physicochemical properties of which vary according to the starting solution concentration. Above the hydrolysis ratio r=1.3, the gelatinous precipitates remain stable and, for r=1.7, the precipitation is complete. The important jump at r=2 coincides with the neutralization of all the acidities of Clearfield's tetramerous entity. The last jump could evidence the formation of a chemical species [Zr2(OH)9]-. Raman spectroscopic characterization of gels leads to identification of two types called α and β. The gel α, existing between the hydrolysis ratios r=1.3 and r=1.7, is formed by condensation of polymeric soluble species whose structure is maintained. Beyond r=1.7, it changes into gel β. The zirconium eight coordination is kept. The study of deuterated preparations allows one to suggest a formulation ZrO2.nH2O for both types of gelatinous precipitate
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European Journal of Solid State and Inorganic Chemistry; ISSN 0992-4361; ; CODEN EJSCE5; v. 30(1-2); p. 179-193
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No abstract available
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Sur l'evolution latitudinale du contenu electronique de l'ionosphere
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Annales de Geophysique; v. 27(3); p. 345-357
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