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  • 1
    Electronic Resource
    Electronic Resource
    Configuration Spaces of Mechanical Linkages (1999)
    Springer
    Discrete & computational geometry 22 (1999), S. 297-315 
    Details
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We present an easy to survey constructive method using only basic mathematics which allows us to define a homeomorphism between any compact real algebraic variety and some components of the configuration space of a mechanical linkage. The aim is to imitate addition and multiplication in the framework of weighted graphs in the euclidean plane that permit a ``mechanical description'' of polynomial functions, and thus of varieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009462
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  • 2
    Electronic Resource
    Electronic Resource
    Photo-induced tunneling spectroscopy of ReS2: Dramatic increase of the quantum efficiency by chemical treatment (1993)
    Springer
    Applied physics 57 (1993), S. 221-223 
    Details
    ISSN: 1432-0630
    Keywords: 68.65 ; 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this work we present a systematic study of the local photovoltaic properties of ReS2, using a scanning tunneling microscope (STM). The tunneling junction of the STM was optically illuminated during the tunneling process. The phase sensitive detected photo-induced tunneling current (PITC) was studied as a function of wavelength and surface topography. In order to improve the performance of ReS2 solar cells, the samples were treated with NaI/I2 and EDTA solutions. Relative to the untreated sample, the EDTA-treated samples show an increase in the photo-induced tunneling current by a factor of 8–10 in the whole spectral range, the NaI/I-treated samples by 2–3. Two dimensional mapping of the PITC was performed on an atomic scale and compared to the surface topography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332592
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  • 3
    Electronic Resource
    Electronic Resource
    CuGaSe2 solar cells with 9.7% power conversion efficiency (1996)
    Springer
    Applied physics 62 (1996), S. 181-185 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 72.70; 85.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  Heterojunctions, such as ZnO/CdS/CuGaSe2, were fabricated for photovoltaic applications. Optimization of device structures based on monocrystalline CuGaSe2 led to the highest-to-date power conversion efficiencies for CuGaSe2 solar cells. At room temperature under 100 mW/cm2 AM1.5 illumination a maximum cell efficiency of 9.7% was achieved, given by an open-circuit voltage of 946 mV, a short circuit current density of 15.5 mA/cm2, and a fill factor of 66.5%. Preparation and performance of the optimum device are described. Current voltage characteristics dependent on illumination intensity and temperature, spectral response and electron-beam-induced current measurements were performed to determine the device parameters as well as to analyse the current transport and loss mechanisms. Tunneling, assisted by defect levels in the CdS layer, seems to play a major role. High injection effects are observed at forward bias of V〉0.5 V or an illumination level of P〉10 mW/cm2. Under such conditions, as well as at low temperatures, the non-zero series resistance comes into play. Effects of the shunt resistance, however, are negligible in all cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050282
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  • 4
    Electronic Resource
    Electronic Resource
    CuGaSe2 solar cells with 9.7% power conversion efficiency (1996)
    Springer
    Applied physics 62 (1996), S. 181-185 
    Details
    ISSN: 1432-0630
    Keywords: 72.70 ; 85.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Heterojunctions, such as ZnO/CdS/CuGaSe2, were fabricated for photovoltaic applications. Optimization of device structures based on monocrystalline CuGaSe2 led to the highest-to-date power conversion efficiencies for CuGaSe2 solar cells. At room temperature under 100 mW/cm2 AM1.5 illumination a maximum cell efficiency of 9.7% was achieved, given by an open-circuit voltage of 946 mV, a short circuit current density of 15.5 mA/cm2, and a fill factor of 66.5%. Preparation and performance of the optimum device are described. Current voltage characteristics dependent on illumination intensity and temperature, spectral response and electron-beam-induced current measurements were performed to determine the device parameters as well as to analyse the current transport and loss mechanisms. Tunneling, assisted by defect levels in the CdS layer, seems to play a major role. High injection effects are observed at forward bias ofV 〉 0.5 V or an illumination level ofP 〉 10 mW/cm2. Under such conditions, as well as at low temperatures, the non-zero series resistance comes into play. Effects of the shunt resistance, however, are negligible in all cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01575717
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  • 5
    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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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    True atomic resolution under ambient conditions obtained by atomic force microscopy in the contact mode (1999)
    Springer
    Applied physics 68 (1999), S. 399-402 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 61.16.Ch; 68.35.Bs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 2 ) has been investigated by contact-mode atomic force microscopy (AFM) in air. Both the terraces and the monolayer step itself were reproducibly imaged at atomic resolution in the repulsive-force regime at forces between tip apex and sample of the order of 10-9 N. Several kinks were also imaged at atomic resolution. Details of the atomic registry of subsequent Se-Nb-Se sandwich layers as well as the arrangement of the individual atoms at the kink sites were resolved. The results are in perfect quantitative agreement with the lattice structure known from X-ray analysis and indicate that true atom-by-atom lateral resolution of microscopic defects is feasible by AFM in the contact mode and under ambient conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050912
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  • 8
    Electronic Resource
    Electronic Resource
    Trends in infant leukaemia in West Germany in relation to in utero exposure due to the Chernobyl accident (1998)
    Springer
    Radiation and environmental biophysics 37 (1998), S. 87-93 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A temporary increase in the incidence of infant leukaemia in Greece was reported by Petridou et al., which was attributed to in utero exposure to ionising radiation resulting from the Chernobyl accident. We performed a similar analysis based on the data of the German Childhood Cancer Registry in order to check whether the observation could be confirmed by means of independent data. Applying the same definitions as Petridou et al., we also observed an increased incidence of infant leukaemia in a cohort of children born after the Chernobyl accident. More detailed analyses, regarding areas with different contamination levels and dose rate gradients over time after the accident, showed, however, no clear trend with regard to exposure. It would therefore appear less likely that the observed effect was caused by exposure to ionising radiation due to the Chernobyl accident.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004110050099
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  • 9
    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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  • 10
    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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