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  • 11
    Electronic Resource
    Electronic Resource
    Temperature and magnetic field dependent correlations in the singlet ground state system CsFeBr3 (1992)
    Springer
    The European physical journal 86 (1992), S. 257-262 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The magnetic excitations in CsFeBr3 have been measured with inelastic scattering of cold neutrons to high precision at 80 mK. The fact that the lowest frequency mode softens with decreasing temperature but stabilizes at 0.11 THz below 2.5 K is the indication that CsFeBr3 remains a SGS system forT→0. From dispersion curves measured earlier in a magnetic field along the chain axis experimental intensities were derived and in turn correlation lengths. Correlation lengths were also calculated using the new parameters for exchange and anisotropy. The experimental results and the calculations both show that the correlation lengths increase for increasing magnetic field, flatten off around the phase transformation at 4.1 Tesla with a maximum of about 35 Å and then decrease again for higher fields. No critical phenomena connected with this phase transformation could be detected. The “Mirror Mode” published earlier was found to be of spurious origin due to double scattering. It does not exist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313834
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  • 12
    Electronic Resource
    Electronic Resource
    Magnetostrictive and quadrupolar anisotropy in nuclear magnetic fcc systems (1992)
    Springer
    The European physical journal 89 (1992), S. 305-311 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spin hamiltonian for nuclear magnetic order in copper is investigated with respect to magnetoelastic couplings to the lattice. These arise due to the dipolar, Ruderman Kittel and the quadrupolar interaction. While the latter is quenched for the ideal fcc-lattice, it is found that for copper it will dominate the magnetoelastic terms of the nuclear spin hamiltonian. The absolute size of the quadrupole contribution is determined by the effective charge and (anti-) shielding effects. This interaction can give rise to an effective anisotropy in the fcc-system which can be quite large compared to the small stabilisation energies for nuclear order in copper. Consequences for the nuclear ordering in copper are briefly discussed and compared to the available experimental and theoretical data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01318161
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  • 13
    Electronic Resource
    Electronic Resource
    Magnetic excitations of CsFeCl3 in an external magnetic field parallel to the hexagonal plane (1994)
    Springer
    The European physical journal 95 (1994), S. 13-21 
    Details
    ISSN: 1434-6036
    Keywords: 75.10.Dg ; 75.25.+z ; 75.30.Et
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In CsFeCl3 the Fe2+-ion with effective spin one has locally a singlet ground state (m s =0). The ferromagnetic interactions along thec-direction and the anti-ferromagnetic interactions perpendicular to it are too week as compared to the anisotropy to introduce longrange order in the absence of an external field. By inelastic neutron scattering we have investigated the excitation spectrum in an external magnetic field up to 6 T applied perpendicular to thec-axis. Preliminary measurements in zero field show that dipolar effects lead to a shift of the minimum of the dispersion curve away from theK-point. We show that with increasing magnetic field the whole dispersion sheet is shifted towards higher frequencies and a splitting appears. With the help of a local Hamiltonian which neglects exchange interactions between all neighbours we give a qualitative explanation of the intensity of the magnetic excitations in dependence of the magnetic field. A more sophisticated theory (RPA-diagonalisation of the Heisenberg-Hamiltonian that is used to describe the magnetic behaviour of CsFeCl3) yields — apart from a mismatch for the modes at high energy transfers — a satisfactory description of the magnetic excitations of CsFeCl3 in dependence of the magnetic field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01316838
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  • 14
    Electronic Resource
    Electronic Resource
    Momentum distributions of projectile fragments produced in the cold and hot fragmentation of relativistic136Xe and197Au projectiles (1993)
    Springer
    The European physical journal 346 (1993), S. 43-46 
    Details
    ISSN: 1434-601X
    Keywords: 25.70.Np
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The longitudinal-momentum distributions of projectile fragments from 0.8 A GeV136Xe and 1 A GeV197Au projectiles impinging on targets of beryllium and aluminium, respectively, have been measured using the projectile-fragment separator FRS at GSI. Different momentum distributions have been found for two different classes of fragmentation processes: the abundant hot fragmentation with several nucleons evaporated from the prefragments, and the rare cold fragmentation with only protons removed from the projectile, but no nucleons evaporated. The data are compared to model calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290780
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  • 15
    Electronic Resource
    Electronic Resource
    Influence of growth conditions on the structural, optical, and electrical properties of ZnSe films (1992)
    Springer
    Applied physics 54 (1992), S. 455-459 
    Details
    ISSN: 1432-0630
    Keywords: 61.10.-i ; 78.55.-m ; 72.80.Ey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract ZnSe films were grown by chemical vapour deposition on GaAs substrates. The influence of the source temperature (between 820 and 900° C) and the substrate temperature (between 620 and 790° C) on the film properties were investigated by Hall measurements, X-ray diffraction, and photoluminescence. With respect to blue luminescent devices the ratio of excitonic to deep level transitions was found to be optimum at low growth rates when the source temperatures were kept below 840° C. P-type conduction up to a net carrier concentration of 8×1018 cm−3 could be obtained by substrate temperatures above 700° C. Lattice contraction versus substrate temperature pointed to a reduced incorporation of donors at higher growth temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324171
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  • 16
    Electronic Resource
    Electronic Resource
    Reflection-scanning near-field optical microscopy and spectroscopy of opaque samples (1994)
    Springer
    Applied physics 59 (1994), S. 103-108 
    Details
    ISSN: 1432-0630
    Keywords: 07.60.Pb ; 07.65.Eh ; 78.65-s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Opaque samples are imaged by Scanning Nearfield Optical Microscopy (SNOM) in reflection mode: A quartz glass fiber tip is used both to illuminate the sample and to collect light locally reflected from or emitted by the surface. The collected light is coupled out by a 2×2 fiber coupler and fed into a grating spectrometer for spectral analysis at each sampled point. The tip-sample distance is controlled by a shear-force feedback system. The simultaneous measurement of topography and optical signals allows an assessment of imaging artifacts, notably topography-induced intensity changes. It is demonstrated that an optical reflectance contrast not induced by topographic interference can be found on suitable samples. Local spectral analysis is shown in images of a photoluminescent layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332201
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  • 17
    Electronic Resource
    Electronic Resource
    Charge-changing cross sections of the neutron-rich isotopes8,9,11Li (1992)
    Springer
    The European physical journal 343 (1992), S. 375-379 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.−k ; 27.20.+n ; 25.70.Np ; 21.10.Re
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Total charge-changing cross sections have been measured for8Li on C and Pb targets, for9Li on C, Al, Cu, Sn and Pb targets, as well as for11Li on C, Sn and Pb targets at about 80 MeV/nucleon. These data are compared to measured total reaction cross sections and Glauber-type calculations using Hartree-Fock density distributions. These comparisons allow to draw conclusions on the proton density distribution of the neutronrich lithium isotopes. The results show that even for the most exotic nucleus11Li the proton distribution is only very weakly influenced by the long tail in the neutron density distribution already established in several experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289813
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  • 18
    Electronic Resource
    Electronic Resource
    Scientific goals and experiments of the project “winter precipitation at Mount Rigi”: An overview (1993)
    Springer
    Water, air & soil pollution 68 (1993), S. 1-14 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Wet deposition plays an important role as a mechanism for cleansing of the polluted troposphere. Fluxes of pollutants from the atmosphere to earth's surface can affect soil and aquatic ecosystems. The investigation of the pollutant incorporation into wet deposition is therefore of considerable interest for environmental research. The project “Winter precipitation at Mount Rigi” addresses the processes determining the chemical composition of wet deposition through an integrated approach considering atmospheric physical and chemical processes and their complex interactions. The investigated topics include: aerosol and gas scavenging, atmospheric chemistry (cloud water chemistry), cloud physics and dynamics. The design of the experiment, using three ground based measuring stations at the northwestern slope of the mountain, and the conceptual ideas using case study investigations are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00479389
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  • 19
    Electronic Resource
    Electronic Resource
    High—Pressure phase transition in67ZnO (1992)
    Springer
    Hyperfine interactions 70 (1992), S. 1067-1070 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using a high-pressure Mössbauer spectrometer for the 93.3-keV resonance in67Zn and an X-ray diffractometer of the Guinier type67ZnO powder was investigated at pressures up to ≈19% at the phase transition. Surprisingly, the center shift (CS) of the cubic phase is by ≈20μm/s more negative than CS of the wurtzite structure. The Mössbauer data as well as theoretical cluster calculations show that the volume collapse is mainly due to the increase in coordination number of nearest-neighbour (nn) atoms. Covalency of the Zn−O bond, however, is reduced due to a≈7% increase of nn distance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02397513
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  • 20
    Electronic Resource
    Electronic Resource
    First principles theory of hyperfine interactions in spinels: ZnAl2O4 (1993)
    Springer
    Hyperfine interactions 78 (1993), S. 403-408 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The nuclear quadrupole interactions of27Al and67Zn, both at the B-site in the spinel ZnAl2O4 have been studied using the Hartree-Fock cluster procedure including the influence of the ions outside the cluster. The theoretical value −3.85 MHz ofe 2 qQ for27Al is in very good a agreement with the experimental value of 3.68 MHz (sign undetermined). For67Zn at the Al site the theoretical value is −8.26 MHz in reasonable agreement with the experimental value of −11.34 MHz indicating that lattice distortion effects associated with Zn as an impurity at the Al site are relatively small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568165
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