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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1618-2650
    Keywords: Oberflächenanalyse ; Spektrometrie, ESCA ; Überblick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The present state of ESCA (Electron Spectroscopy for Chemical Analysis) is reviewed with emphasis on chemical applications. It is shown that in metals the electron spectra are modified significantly by many body effects, which manifest themselves in an asymmetric lineshape for the core lines and the occurrence of many plasmons. These effects make it difficult to determine concentrations directly from line intensities. Studies of adsorbates on metal surfaces allow conclusions on the nature of the bonding between the surface and adsorbate molecules and the geometric configuration of the adsorbate molecules relative to the surface.
    Notes: Zusammenfassung Der augenblickliche Stand der ESCA (Elektronen-Spektroskopie zur Chemischen Analyse) Spektroskopie wird im Hinblick auf die chemischen Anwendungen dieser Technik beschrieben. Es wird gezeigt, daß in Metallen die Spektren durch Vielteilcheneffekte erheblich verzerrt werden: diese machen sich durch eine asymmetrische Linienform und das Auftreten von Plasmonen bemerkbar. Diese Effekte erschweren die direkte Konzentrationsbestimmung aus Linienintensitäten. Untersuchungen von Adsorbaten auf Metalloberflächen erlauben Rückschlüsse über die Natur der Bindung zwischen den Oberflächen- und Adsorbatmolekülen und über die geometrischen Konfigurationen des Adsorbatmoleküls relativ zur Oberfläche.
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  • 2
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The oxidation of polycrystalline Zr under 10−8-10−3 mbar oxygen pressure in the temperature range 25 °–350 ° C is obtained from ESCA experiments. Changes in the ESCA spectra for thin Zr films on Ag oxidized at 250 ° C are observed and compared to the bulk Zr-metal. Thin Ag overlayers on Zr show a catalytic increase of the room temperature oxidation of Zr.
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  • 3
    ISSN: 0044-2313
    Keywords: CVD of tert-butoxides of Ge, Sn, Pb ; mixed metal tert-butoxides in CVD ; nano-composites metal/metaloxide ; XPS of nano-composites ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and XPS Analysis of nano-scaled Metal/Metaloxid Composites with Germanium, Tin, and Lead as Metallic Componenttert-Butanolates of Germanium(II), tin(II), and lead(II) of the formula {M[O-C(CH3)3]2}n (M = Ge, n = 2; M = Sn, n = 2; M = Pb, n = 3) as well as the corresponding heterometalalkoxides M′M2[O—C(CH3)3]6 (M = Ge, M′ = Sr, Ba; M = Sn, M′ = Ca, Sr, Ba; M = Pb, M′ = Ca, Ba) have been subject to a single precursor chemical vapour deposition (CVD) process. In this process the volatile precursor has been pyrolized under reduced pressure (0,1 Torr) on a graphit or metal substrate which has been heated by induction in a microwave field to about 300-500°C. The gases originating from this pyrolisis have been analyzed by means of a quadrupole mass spectrometer whereas the solid coating which contained the micro composite was characterized by X-ray diffraction, electron microscopy, EDX-analysis and XPS-spectra. In all cases the solid material contained two phases, in which the element M ((Ge), Sn, Pb) either had oxidation state 0 or +4 (in the surface of the solids made of germanium containing precursors only GeII along with Ge0 has been detected by XPS spectroscopy). The group 14-element in the starting material had thus undergone a disproportionation from the +2 oxidation state into a lower and a higher one by two units. The elemental phase and the phase containing the formal +4 cation which is amorphous in most cases and which approaches the formula MO2 or M′MO3 (M = (Ge), Sn, Pb; M′ = Ca, Sr, Ba) are uniformally distributed. The composites consist of ball shaped particles on which other smaller particles are placed in a fractal manner ressembling a black berry. In the case of the composite Sn · BaSnO3 the center of the ball shaped particles has been analyzed as pure elemental tin. The organic substituents of the precursors as well as the dynamic vacuum in the decomposition process seem to be responsible for the ball shaped nature of the solid material. In a test experiment gallium tri-tert-but-oxide has been used as precursor: again ball shaped particles are obtained which have the chemical composition Ga2O3 but which contain no elemental gallium.
    Notes: tert-Butanolate von Germanium(II), Zinn(II) und Blei(II) der Formel {M[O—C(CH3)3]2}n (M = Ge, n = 2; M = Sn, n = 2; M = Pb, n = 3) sowie die entsprechenden Heterometallalkoxide M′M2[O-C(CH3)3]6(M = Ge, M′ = Sr, Ba; M = Sn, M′ = Ca, Sr, Ba; M = Pb, M′ = Ca, Ba) wurden in einem CVD-Prozeß (Chemical Vapour Deposition) als Einkomponenten Precursoren eingesetzt. In dem Prozeß wird der flüchtige Precursor unter reduziertem Druck auf einem Graphit- oder Metall-Target bei 300-500°C pyrolisiert, wobei das Target in einem Mikrowellenfeld aufgeheizt wird. Die entstehenden Gase dieser Pyrolyse werden über ein Quadrupol-Massenspektrometer analysiert. Die sich bildende feste Schicht, die einen Mikrokomposit enthält, wird mit Röntgenbeugung, Elektronenmikroskopie, EDX-Analyse und XPS-Spektren untersucht. In allen Fällen enthält der dargestellte Feststoff zwei Phasen, in denen die Elemente Ge, Sn und Pb sowohl in der Oxidationstufe 0 als auch +4 enthalten sind (in den Germanium enthaltenden Proben kann auf der Oberfläche über XPS neben Ge0 nur GeII nachgewiesen werden). Das im Startmolekül enthaltene Gruppe 14-Element hat demnach, ausgehend von der Oxidationsstufe +2, in eine um zwei Einheiten höhere bzw. niedere Oxidationsstufe disproportioniert. Die Elementphase und die meist amorphe Phase, die das formale +4 Kation enthält und die den Formeln MO2 bzw. M′MO3 (M = (Ge), Sn, Pb; M′ = Ca, Sr, Ba) nahe kommt, sind innig ineinander vermischt. Die Komposite bestehen aus kugelförmigen Gebilden, auf deren Oberfläche weitere kleine Kugeln sitzen, auf welche wieder kleinere Kugeln aufgewachsen sind, so daß ein Fraktal entsteht, dessen oberste Struktur einer Brombeere gleicht. Im Fall des Komposits Sn · BaSnO3 wurde das Zentrum der Kugelansammlung als reines Zinn identifiziert. Die organischen Substituenten der Startmoleküle und die dynamische Veränderung des Unterdrucks bei der Zersetzung haben einen Einfluß auf das Entstehen der kugeligen Gebilde. In einem Testexperiment wurde auch Galliumtritert-butoxid als Precursor eingesetzt: man findet auch wieder kugelförmige Gebilde der Zusammensetzung Ga2O3, jedoch enthalten diese Feststoffe kein elementares Gallium.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 164 (1961), S. 269-273 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Zusammenfassung Die Terme des Ho3+-Ions werden durch Diagonalisieren der vollständigen Matrizen der Coulomb-Abstoßung und der Spin-Bahn-Wechselwirkung für die Elektronenkonfigurationf 10≙f −4 berechnet. Es besteht gute Übereinstimmung in denJ-Werten und den Termenergien zwischen Experiment und Theorie.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 165 (1961), S. 397-401 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Zusammenfassung Es werden die Terme des Pm3+-Ions für den Fall der mittleren Kopplung berechnet und mit dem an einer Lösung von PmCl3 in D2O gewonnenen Absorptionsspektrum verglichen.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 168 (1962), S. 74-80 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Zusammenfassung Das Absorptionsspektrum des Erbium-Äthylsulfats und des Erbium-Chlorids in kristallinen Salzen wurde im ultravioletten Spektralbereich bei Temperaturen von 4,2 °K und 77 °K aufgenommen und gedeutet. Die Zuordnung zwischen den experimentell gefundenen und den theoretisch berechneten Termen gelingt bis zu einer Energie von 40000 cm−1.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 187 (1965), S. 67-84 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The isomer shift of the 21.7 keVγ transition in Eu151 has been studied for various divalent and trivalent europium compounds using the Mössbauer technique. Theγ energy is lower by up to 1.1·10−6 eV in divalent compounds than in trivalent compounds. Using data from atomic spectroscopy it is estimated that the electron density at the nucleus is larger by about 1.9·1026cm−3 for the configuration 4f 6 than for 4f 7 due to different shielding of thes 2 shells. The difference of the mean square radii of the 21.7 keV state and the ground state is thenδ〈r2〉=+0.03 fm2. The measured isomer shift between trivalent and metallic europium and the relatives-electron densities in the rare earth metals measured by the positron annihilation rates are used to establish a calibration scheme for isomer shifts in rare earth metals. This calibration scheme is used to deduce a changeδ〈r 2〉=+0.0055 fm2 between the 26 keV state and the ground state of Dy161.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 204 (1967), S. 101-113 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The absorption spectrum of single crystals of ErFeO3 has been investigated in the red and near infrared spectral region in the temperature range between 1.2 °K and 4.2 °K and at 20 °K and 77 °K. Between 77 °K and 4.2 °K a constant splitting of the absorption lines is observed. Below the Néel-temperature of the erbium sublattice at 4.5 °K the splitting of the absorption lines increases; the saturation value extrapolated to 0 °K of the splitting of the lowest crystal field level of the4 I 15/2 groundterm is (6.08±0.30) cm−1. By measuring the Zeeman effect the groundstate magnetic moment is determined asμ=(6.6±0.2)μ B. The measured temperature dependence of the splitting of the lowest crystalfield level of the4I15/2 groundterm is compared with that calculated by a Monte Carlo method.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 228 (1969), S. 235-253 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The absorption spectrum of antiferromagnetic dysprosium aluminium garnet (DAG) (T N =2.50 °K) has been investigated at low temperatures. The groundstate splitting due to all interactions in the antiferromagnetic state is (5.27±0.10) cm−1 extrapolated to 0 °K. The temperature dependence of the lineshift of the absorption lines is measured. Zeeman effect studies give theg-tensor of the groundstate asg z =18.4±0.5,g x =g y =0.5±0.2. The studies also allow the determination of the critical fields asH c [100] =(5.0±0.1) koe,H c [111] =(3.9±0.2) koe andH c [110] =(4.9±0.6) koe. In addition an investigation of a number of satellite lines is performed. Some of them can be interpreted as spin wave sidebands (Stokes and anti-Stokes); others obviously come from dysprosium ions which have impurity ions on regular lattice sites as neighbours.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 232 (1970), S. 418-429 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Absorption spectra of the transition4 I 15/2→4 I 9/2 have been measured in erbium iron garnet (ErIG). From these spectra the exchange tensors for four Kramers dubletts can be obtained. A tentative analysis of these data in terms of a phenomenological exchange Hamiltonian will be presented.
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