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  • 1
    Electronic Resource
    Electronic Resource
    Synchrotron radiation x-ray absorption of ion bombardment induced defects on diamond (100) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7483-7486 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface defect structures on diamond (100) surfaces induced by 500 eV neon ion bombardment and by subsequent annealing were studied in situ with x-ray absorption near-edge structure (XANES) spectroscopy using 250–800 eV synchrotron radiation and with low energy electron diffraction. Ex situ x-ray photoemission spectroscopy (XPS) was also used to characterize the defective layer. Significant changes in the XANES spectra were identified for the defects induced by ion bombardment and subsequent annealing. The diamond discrete exciton absorption at 289.0 eV was clearly suppressed even at the lowest ion fluence used in this study, i.e., 3×1014/cm2, and no such exciton could be observed at 7×1014/cm2. However, the changes in the multi-maxima shape-resonance absorption structure in the range of 290–310 eV indicated that a loss of the diamond long range order required a fluence of 1×1015/cm2. The structural changes were also manifested by the transformation of gap state absorption typical of clean 2×1 surfaces to the π* absorption typical of amorphous carbon. XPS showed that the defective layer was about 2 nm thick. For all samples prepared with the bombardment conditions in the study, both the XANES and XPS data also indicated no phase transformation from defective layers to graphite even after annealing to a temperature of 1100 °C. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357977
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  • 2
    Electronic Resource
    Electronic Resource
    Phonon mode study of near-lattice-matched InxGa1−xAs using micro-Raman spectroscopy (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1927-1929 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We identify the four allowable phonon modes in InxGa1−xAs on InP:InAs-like transverse optical (TO) (225±2 cm−1), InAs-like longitudinal optical (LO) (233±1 cm−1), GaAs-like TO (255±2 cm−1), and GaAs-like LO (269±1 cm−1), using the selectivity of first-order Raman scattering off the (100) normal surface and the (011) cleaved plane and detailed line-shape analysis employing a sequential simplex optimization procedure. Raman scattering off the (011) cleaved plane was achieved for the first time in thin-film InGaAs using microprobing capabilities (∼1 μm). We also identify another phonon mode R* at 244 cm−1 which is attributed to an alloy disorder mode in these films. For the five identified phonon modes, a linear relationship between the Raman frequencies and composition determined from x-ray diffraction was determined for near-lattice-matched conditions (0.42〈1−x〈0.52).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108366
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  • 3
    Electronic Resource
    Electronic Resource
    Anomalous photoluminescence behavior of porous Si (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 803-805 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the photoluminescence (PL) behavior of porous Si and have found that the PL intensity rises with time under exposure to continuous laser light at high power densities ((approximately-greater-than)50 W/cm2). Samples exposed to lower power density laser light exhibit the well-known degradation of its PL intensity. As the power density is raised, the PL intensity increases with time and shows a "window'' effect in which the PL intensities will again degrade at higher power density. Micro-Raman studies were performed on the sample and no apparent change in crystalline structure could be found for differing power densities. We correlate this anomalous PL effect with porous Si samples etched with different HF acid concentrations and show that this effect occurs only for porous Si samples etched with a relatively high acid concentration ((approximately-greater-than)30%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109913
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  • 4
    Electronic Resource
    Electronic Resource
    Direct evidence for the amorphous silicon phase in visible photoluminescent porous silicon (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 563-565 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on micro-Raman spectroscopy studies of porous silicon which show an amorphous silicon Raman line at 480 R cm−1 from regions that emit visible photoluminescence. A Raman line corresponding to microcrystalline silicon at 510 R cm−1 is also observed. X-ray photoelectron spectroscopy data is presented which shows a high silicon-dioxide content in porous silicon consistent with an amorphous silicon phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107837
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  • 5
    Electronic Resource
    Electronic Resource
    Post-growth tailoring of the optical properties of GaAs/AlGaAs quantum well structures (1991)
    Springer
    Optical and quantum electronics 23 (1991), S. S915 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract In this paper we describe a method for performing post-growth bandgap engineering in the GaAs/AlGaAs quantum well system. The method used is impurity-free vacancy diffusion. Using both single and multiple quantum well data we show that this allows blue shifts in the optical properties, while retaining both their distinctive excitonic and electrical characteristics. The electrical response is modelled and no comparative degradation of the quantum confined Stark effect is predicted, and this is confirmed experimentally. Possible applications of this technique are mentioned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00624981
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of protease inhibitors and dietary protein level on the black field cricket Teleogryllus commodus (1991)
    Springer
    Entomologia experimentalis et applicata 61 (1991), S. 123-130 
    Details
    ISSN: 1570-7458
    Keywords: Protease inhibitors ; dietary protein ; crickets ; Teleogryllus commodus ; single gene resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth and survival responses were determined for black field crickets Teleogryllus commodus (Walker) (Orthoptera: Gryllidae) on artificial diets containing a range of levels of dietary protein, and protease inhibitors (PI's) at 0.33% (weight volume, w:v). The effect on cricket gut enzyme activities of adding PI's to a high protein diet was measured. All PI's which had in vitro binding activity against either trypsin or elastase (the two major cricket gut endopeptidases) reduced growth, but those which bound to both enzymes had the greatest effect. None of the PI's acted as a source of nutritional protein. Cricket growth rate increased with the addition of casein up to 3% w:v, but not with a similar addition of wheatgerm. The impact of PI's on growth was greatest on a 1.5% casein diet. On a high protein (3% casein) diet, the gut activity of trypsin was increased by potato proteinase inhibitors 1 and 2 while the activity of elastase and leucine amino peptidase were increased by soybean trypsin inhibitor and potato proteinase inhibitor 2. Increasing dietary casein up to 3.3% improved cricket survival. The potential of PI's as plant resistance factors against crickets was confirmed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191742
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  • 7
    Electronic Resource
    Electronic Resource
    Nafion®-bonded porous titanium oxide electrodes for oxygen evolution: towards a regenerative fuel cell (1991)
    Springer
    Journal of applied electrochemistry 21 (1991), S. 982-985 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Oxygen evolution on PTFE/Nafion®-bound porous activated XC-72 carbon and on PTFE- and PTFE/Nafion®-bound Ebonex® has been studied, using RuO2/IrO2 catalysts. High activity was found for Ebonex®, but carbon, even when coated with Nafion, proved qquite unstable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01077583
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  • 8
    Electronic Resource
    Electronic Resource
    The J.H.B. bookshelf (1992)
    Springer
    Journal of the history of biology 25 (1992), S. 497-504 
    Details
    ISSN: 1573-0387
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , History
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00352005
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  • 9
    Electronic Resource
    Electronic Resource
    In defence of taxonomy (1990)
    [s.l.] : Nature Publishing Group
    Nature 347 (1990), S. 222-223 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR-The taxonomic Brave New World outlined by Clifford et al. is strange indeed: natural history collections, they say, are not needed because chemists do not store the compounds they synthesize; taxonomy should be based on descriptions and type specimens and should have a rational economic basis. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/347222c0
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  • 10
    Electronic Resource
    Electronic Resource
    A genetic analysis of the pea crabs (Decapoda: Pinnotheridae) of New Zealand (1991)
    Springer
    Marine biology 108 (1991), S. 403-410 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven populations of the pea crabPinnotheres atrinicola Page were sampled from around the North Island of New Zealand from February to October 1987, and individuals were scored at 23 presumptive enzymatic loci. For a brachyuran crab,P. atrinicola revealed high levels of polymorphism and heterozygosity. Of the loci scored, phosphoglucose isomerase (Gpi) and phosphoglucomutase (Pgm) were distinguished by high variability ( $$\bar H$$ =0.602 and 0.526, respectively). A clinal variation in electromorph frequency was evident at several loci, and atGpi in particular. Statistical analyses revealed that, despite relatively small genetic distance separation, a high degree of structuring was present between the geographic populations. The degree of population subdivision observed in this study is atypical of brachyuran crabs. It is suggested that the genetic differentiation observed between pea crab populations is maintained by life-history attributes and current movements which restrict gene flow between populations and, to some extent, by random genetic drift.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313649
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