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561.
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Leopold Fejér 《Monatshefte für Mathematik》1917,28(1):64-76
Ohne Zusammenfassung 相似文献
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S. Schloter A. Schreiber M. Grasruck A. Leopold M. Kol’chenko J. Pan C. Hohle P. Strohriegl S.J. Zilker D. Haarer 《Applied physics. B, Lasers and optics》1999,68(5):899-906
We present a detailed study of the photoelectric as well as the holographic properties of a novel organic photorefractive
glass based on triphenylamine. We studied the quantum efficiency Φ of the photogeneration of charges by means of photoinduced
discharge measurements. The photoconductivity σ and the charge carrier mobility μ were obtained via dc photoconduction and
pulsed time-of-flight experiments, respectively. The holographic characterization was performed by two-wave and degenerate
four-wave mixing experiments allowing for the determination of properties such as diffraction efficiency η, modulation of
the refractive index Δn, gain coefficient Γ, and phase-shift φp of the investigated system. The experimental data for Φ could be successfully described by the Onsager formalism with a thermalization
radius of r0=24 ? and a primary quantum yield of Φ0=40%. We evaluated the E field and temperature-dependent measurements of μ using the B?ssler formalism yielding a width of
the density of states of σ=0.13 eV and a disorder parameter Σ=3.6. On this basis the lifetime and the average drift length
of the charge carriers could be estimated from the dc photoconduction experiments. From the photoelectric measurements we
also calculated the holographic response time that matched very well to the measured response time and described the E-field
dependence satisfactorily. The presented photorefractive system shows outstanding optical properties and stability with respect
to degradation. We measured a gain coefficient of Γ=90 cm-1, and a diffraction efficiency of η=27% at a response time of 30 ms for only 40-μm-thick samples. Orientational enhancement
was observed and evaluated quantitatively. To our knowledge, this work presents the first determination of each of the above
quantities all in one single organic photorefractive material.
Received: 16 November 1998 / Revised version: 4 January 1999 / Published online: 31 March 1999 相似文献
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supported by DFG-contract Ja 522/3-1 相似文献
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Franki Dillen Leopold Verstraelen Ignace Van de Woestyne Leopold Verstraelen Johan Walrave 《Results in Mathematics》1995,27(3-4):250-255
We show that a ruled surface M in E1 3 is of finite type if and only if M is minimal, or M is a part of a circular cylinder, or M is a part of a hyperbolic cylinder, or M is an isoparametric surface with null rules. We also give a complete classification of isoparametric ruled surfaces with null rules. 相似文献
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