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  • 1990-1994  (4)
  • 1970-1974
  • 1991  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Photoluminescence characterization of InP surface reactive ion etched by a gas mixture of ethane and hydrogen (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2361-2365 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InP crystals were etched by reactive ion etching (RIE) with gas mixture of ethane and hydrogen (C2H6/H2), and etching damages were characterized by photoluminescence (PL) measurements of near-edge and defect-related emissions. Near-edge PL emission intensities after RIE were equal to or larger than those before RIE, except for the samples etched for 50 min. The damage introduced by RIE was restricted to the very-near-surface region which can be removed by HF treatment. The peak energy of defect-related 1.1-eV deep emission bands shifted toward the lower-energy side for the crystals with etching damages at the surface. The peak shift is attributable to the increase of defect complexes such as P-vacancy–P-interstitial or P-vacancy–In-vacancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349436
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Slow response and Eu2+-related trapping states in CaS:Eu thin-film electroluminescent devices (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5018-5024 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to clarify causes of the slow buildup of the optical output, i.e., slow optical response, in red-emitting CaS:Eu thin-film electroluminescent devices, Eu2+ concentration and temperature dependence of the response time of transferred electrons were measured. It was found that the response time increased exponentially with the increase in Eu2+ concentration and temperature. To understand these results, trapping states in CaS:Eu phosphor layer were studied by measuring temperature dependence of the following electro-optical characteristics with Eu2+ concentration as a parameter; (i) decay profile of trapped electrons, (ii) photoluminescent intensity, and (iii) photoinduced charge density. From these measurements, it was found that there existed two kinds of shallow states in the band gap of CaS. One was electron trapping states located at approximately 0.15 eV below the conduction-band minimum. These states were considered to be generated by Eu2+ clusters. The other was located at 0.06–0.08 eV below the conduction-band minimum. These states were considered to be 5d-excited states of isolated Eu2+ activators. Based on these experimental results, an energy band model for CaS:Eu thin film was proposed and causes for the slow optical response were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349006
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Instabilities and vortex dynamics in shear flow of magnetized plasmas (1991)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 938-954 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gradient-driven instabilities and the subsequent nonlinear evolution of generated vortices in sheared E×B flows are investigated for magnetized plasmas with and without gravity (magnetic curvature) and magnetic shear by using theory and implicit particle simulations. In the linear eigenmode analysis, the instabilities considered are the Kelvin–Helmholtz (K–H) instability and the resistive interchange instability. The presence of the shear flow can stabilize these instabilities. The dynamics of the K–H instability and the vortex dynamics can be uniformly described by the initial flow pattern with a vorticity localization parameter ε. The observed growth of the K–H modes is exponential in time for linearly unstable modes, secular for the marginal mode, and absent until driven nonlinearly for linearly stable modes. The distance between two vortex centers experiences rapid merging while the angle θ between the axis of the vortices and the external shear flow increases. These vortices proceed toward their overall coalescence, while shedding small-scale vortices and waves. The main features of vortex dynamics, the nonlinear coalescence and the tilt or the rotational instabilities of vortices, are shown to be given by using a low-dimension Hamiltonian representation for interacting vortex cores in the shear flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859850
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Thermodynamics of complexation of zinc(II) with chloride, bromide and iodide ions in hexamethylphosphoric triamide (1991)
    Springer
    Journal of solution chemistry 20 (1991), S. 793-803 
    Details
    ISSN: 1572-8927
    Keywords: Thermodynamics of complexation ; zinc(II) halogeno complexes ; hexamethylphosphoric triamide ; titration calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation of zinc(II) with chloride, bromide and iodide ions has been studied by calorimetry in hexamethylphosphoric triamide (HMPA) containing 0.1 mol-dm−3 (n-C4H9)4NClO4 as a constant ionic medium at 25°C. The formation of [ZnXn](2−n)+ (n=1,2,3,4 for X=Cl; n=1,2 for X=Br, I) is revealed, and their formation constants, enthalpies and entropies were determined. It is proposed that the zinc(II) ion is fourcoordinated in HMPA and the coordinating HMPA molecules are stepwise replaced with halide ions to form [ZnXn(hmpa)4−n](2−n)+ (n=1−4), as is the case for the cobalt(II) ion. Furthermore, the formation of [ZnClI], [ZnBrI], [ZnBrCl] and [ZnBrCl2]− is revealed in the relevant ternary systems. It is found that the affinity of a given halide ion X− to [ZnCl]+, [ZnBr]+ and [Znl]+ is practically the same.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00675111
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    Paper (German National Licenses)
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