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  • 2005-2009
  • 1985-1989  (5)
  • 1986  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Influence of phosphorus vapor ambient for InGaAsP growth on GaAs substrate (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 3895-3899 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For visible-light-emitting laser diodes, InGaAsP double heterostructures have been grown on GaAs substrates using liquid-phase epitaxy. As the growth temperature is as high as about 780 °C, a large amount of phosphorus evaporates from the solutions for the cladding layers during the growth process. The phosphorus vapor disturbs the solution composition for the active layer, so that very thin and uniform active layers cannot be obtained. By using In-P-Sn solution and supplying the phosphorus partial pressure around the graphite boat, the influence of phosphorus vapor ambient for InGaAsP (λPL=805 nm) growth is confirmed. When the phosphorus partial pressure increases, the surface of epitaxial layer becomes rough and the substrate is partly etched back. From x-ray diffraction and photoluminescence spectral measurements, the composition of the grown layer is also found to be changed. As a result of increasing the flow rate of H2 gas in order to protect the solution for the active layer from phosphorus contamination, the double heterostructure wafers with the high-quality active layer can be obtained reproducibly. Thus, pulsed lasing operation at room temperature has been achieved. The lasing wavelength is 816 nm and the threshold current density is ∼4.6 kA/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337562
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fabrication methods for InGaAsP/GaAs visible laser structure with AlGaAs burying layers grown by liquid-phase epitaxy (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 761-768 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Liquid-phase-epitaxial (LPE) growth of AlGaAs layers has been used in fabricating InGaAsP buried heterostructure visible lasers on GaAs substrate. InGaAsP/InGaAsP double heterostructure wafers were grown on the p-type GaAs substrates by means of the melt-back method prior to the LPE growth for eliminating phosphorus contamination. An SiO2 film mask was deposited on the epitaxial wafer surface by the rf sputtering, and photoetched with stripes of 7–10 μm width in the 〈110〉 direction. After etching to the first p-InGaAsP cladding layer with a 3% Br-methanol solution, the second LPE growth of n-AlGaAs and p-GaAs layers was carried out. The InGaAsP active region is entirely surrounded by the InGaAsP cladding layers and the AlGaAs burying layer, therefore, it becomes possible to provide both lateral and vertical carrier and optical confinements. I-L characteristics were measured at room temperature under pulsed operation, but the lasing action was not obtained. The peak wavelength of the electroluminescence was 785 nm. The transverse mode behavior was analyzed by means of the effective refractive index approximation. And it seemed that this buried heterostructure is suitable for the transverse mode control of InGaAsP visible laser diodes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337034
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Metabolism of gibberellins in a cell-free system from immature seeds of Phaseolus vulgaris L. (1986)
    Springer
    Planta 168 (1986), S. 190-199 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin biosynthesis ; Phaseolus (gibberellins) ; Seed (gibberellins)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biosynthetic steps from gibberellin A12-aldehyde (GA12-aldehyde) to C19-GAs were studied by means of a cell-free system from the embryos of immature Phaseolus vulgaris seeds. Stable-isotope-labeled GAs were used as substrates and the products were identified by gas chromatography-mass spectrometry. Gibberellin A12-aldehyde was converted to GA4 via non-hydroxylated intermediates and to GA1 via 13-hydroxylated intermediates. 13-Hydroxylation took place at the beginning of the pathway by the conversion of GA12-aldehyde to GA53-aldehyde. The conversion of GA20 to GA5 and GA6 was also shown but no 2β-hydroxylating activity was found. Endogenous GAs from embryos and testas of 17-dold seeds were re-examined by gas chromatography-selected ion monitoring using stable-isotopelabeled GAs as internal standards. Gibberellins A9, A12, A15, A19, A23, A24, and A53 were identified for the first time in P. vulgaris, in addition to GA1, GA4, GA5, GA6, GA8, GA17, GA20, GA29, GA37, GA38 and GA44, which were previously known to occur in this species. The levels of all GAs, except the 2β-hydroxylated ones, were greater in the embryos than in the testas. Conversely, the contents of GA8 and GA29, both 2β-hydroxylated, were much higher in the testas than in the embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402963
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The loss of carbon-20 in C19-gibberellin biosynthesis in a cell-free system from Pisum sativum L. (1986)
    Springer
    Planta 169 (1986), S. 524-528 
    Details
    ISSN: 1432-2048
    Keywords: Gibberellin (C20→C19 conversion) ; Pisum (gibberellin synthesis)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fate of the carbon-20 atom in gibberellin (GA) biosynthesis was studied in a cell-free system from Pisum sativum. This carbon atom is lost at the aldehyde stage of oxidation when C20-GAs are converted to C19-GAs. Gibberellin A12 labeled with 14C at C-20 was prepared from [3′-14C]mevalonic acid with a cell-free system from Cucurbita maxima and incubated with the pea system. Analysis of the gas and aqueous phases showed that 14CO2 was formed at the same rate and in nearly equivalent amounts as 14C-labeled C19-GAs whereas [14C]formic acid and [14C]formaldehyde were not detectable. The possibility that C-20 had been lost as formic acid which had then been converted to CO2 was investigated by control incubations with [14C]formic acid. The rate of release of 14CO2 from [14C]formic acid was only one fiftieth of the rate of 14CO2 release from [14C]GA12 as the substrate. We conclude that in the formation of C19-GAs from C20-GAs, the C-20 is removed directly as CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392102
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The mechanism of the reaction of elementary astatine with organic solvents (1986)
    Springer
    Journal of radioanalytical and nuclear chemistry 103 (1986), S. 1-9 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The mechanism of the reaction of elementary astatine with benzene, toluene and monochlorobenzene were studied by means of radiogaschromatography. The reaction proceeds in two steps with benzene and toluene. In Step 1 the chemical bond of At2 is cleaved by the disintegration of either astatine and the remained astatine reacts immediately with solvent. At Step 2 the compound produced at Step 1 is started to decompose by the decay of astatine. But this mechanism could not be applied to the astatine-monochlorobenzene system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02165358
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    Paper (German National Licenses)
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