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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2516-2519 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The field-dependence of the charge photogeneration efficiency reduces the holographic contrast in an organic photorefractive composite. In this article, the Braun model for field-dependent photogeneration efficiency is incorporated into the standard model of photorefractivity. Using this formalism, the effect on the space-charge field, and thereby holographic index contrast, is calculated directly without the need for empirically found parameters. The dependence of the space-charge field on experimental geometry is also analyzed. A powerful description of the effective space-charge field is thus derived and is experimentally verified. This analysis is then used to compare the observed holographic contrast to that predicted from transmission ellipsometry measurements. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 231-236 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The poling of dipoles in dispersive media under the influence of an applied electric field and the subsequent relaxation after the removal of the applied field have been analyzed. Both the poling and relaxation processes are described by simple and exact analytical solutions to the rotational diffusion equation. The resulting expressions for the order parameters are power laws with respect to time and hence have no characteristic lifetimes. The poling and relaxation rates are, in fact, determined by a single material parameter: the diffusion constant, D0. These theoretical results have been experimentally verified for dipolar molecules doped into an amorphous polymer host. An excellent agreement between theory and measurement was found. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK; Malden , USA : Blackwell Science Inc
    Restoration ecology 12 (2004), S. 0 
    ISSN: 1526-100X
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Induced mycorrhization of sweet birch (Betula lenta L.) by Pisolithus tinctorius (Pers.) Coker & Couch, as influenced by substrate fertility, was evaluated for its effects on seedling growth and physiology. Following a brief period in seed flats, seedlings were transplanted to mine spoil where they resided for 30 months, and three nutrition regimes were imposed throughout the study by application of differing nutrient solution concentrations. High fertility suppressed mycorrhizal formation by P. tinctorius but promoted that of other mycobionts. Pisolithus mycorrhization induced substantial aboveground and belowground growth as indicated by dimensions and mass for the former and mass and length for the latter but favoring root over shoot growth overall. Furthermore, these mycorrhizae were frequently able to compensate for the growth stimulation of higher nutrient additions. Measurements of xylem pressure potential and soil water potential indicated that water uptake was enhanced by P. tinctorius during simulated drought episodes of two durations and in subsequent recovery periods. Inoculated seedlings had higher foliar concentrations of critical nutrients, especially N, and lower concentrations of potentially phytotoxic metallic elements, particularly Mn, than uninoculated seedlings, although the latter response was absent in high fertility. Spoil analyses clearly revealed the influence of the nutrition regimes but also the effects of seedling uptake on substrate chemistry, and reinforced the findings of the foliar analysis concerning suppression of metal uptake by P. tinctorius. Collectively, these results suggest that P. tinctorius can provide sweet birch an array of physiological benefits that will permit this tree species to flourish on harsh substrates such as surface mine spoils without heavy application of chemical fertilizers.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 82 (1960), S. 280-283 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 86 (1964), S. 4731-4732 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 77 (1955), S. 242-244 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Analytical chemistry 31 (1959), S. 583-586 
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Analytical chemistry 31 (1959), S. 586-588 
    ISSN: 1520-6882
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1067-1068 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have fabricated a metal-semiconductor-metal Schottky photodetector on a semi-insulating InP substrate using a nominally lattice-matched In0.52Al0.48As/In0.53(GaxAl1−x)0.47As (graded)/In0.53Ga0.47As structure grown by molecular beam epitaxy. On average the graded quaternary layer enhanced the responsivity by about 35% compared to an identical device without the graded region, reaching a maximum of 0.45 A/W at 10 V applied bias. The associated dark current was 95 nA; the dark capacitance was 90 fF. High-speed measurements with a gain-switched 1.3 μm laser diode demonstrated an instrumentation-limited impulse response of 50 ps.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 5893-5899 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The photorefractive properties and the phase stability of polymer composites are dependent on the detail of the alkyl chain substituent attached to the electro-optic dye within the composite. Photorefractive composites based on poly (N-vinylcarbazole) (PVK), sensitized with trinitrofluorenone (TNF) and mixed with a concentration of 47.5 wt. % of electro-optic dye have been tested for photorefractive performance. Two alternative azo dyes of identical molecular weight have been used to produce alternative composites; both dyes were modified to suppress spatial isomerism and incorporated an eight carbon alkyl chain at the electropositive end of the chromophore: either a straight octyl chain or a branched ethylhexyl chain was substituted. The reorientational enhancement of photorefractive performance is similar in the composites resulting from these dyes. The dye with a straight octyl chain led to a composite with improved holographic performance. The dye with a branched ethylhexyl chain led to a composite exhibiting lower diffraction efficiency, but with superior phase stability. A tentative explanation is offered for these differences based on the shape of the alkyl substituent and its effect on a trapping mechanism involving the dye molecules and the sensitisor anions in PVK:TNF-based photorefractive composites. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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