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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 410 (2001), S. 168-168 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The rigorous size miniaturization of nanotechnology is continually generating new applications and new physical effects. We show here that nanotubes can be formed from thin solid films of almost any material at almost any position, once these films are released from their substrate. This ...
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3723-3725 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Investigations on near-surface diffusion during the formation of self-assembled Ge islands on Si(001) are presented. We measure the detailed shape of trenches around islands that are formed due to short range, strain enhanced diffusion. It is found that these trenches have anisotropic shape which we explain in terms of the intrinsic anisotropy of the elastic properties for the Si crystal. At high growth temperatures, long-range depletion of the substrate and trench formation between neighboring islands due to strong in-diffusion of Si into the nominally pure Ge islands is observed. A simple diffusion model which predicts trench depths as a function of island distance fits well to our experimentally observed data. Calculated diffusion lengths from this model are comparable to the average island distance on the surface. © 2001 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 356-358 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown high-quality In0.48Ga0.52P layers on GaAs(001) substrates using solid-source molecular-beam epitaxy. A dimer phosphorous (P2) molecular beam was produced from a GaP decomposition source. The full width at half-maximum of the (004) double-crystal x-ray diffraction peak from a 1.7-μm-thick InGaP layer on GaAs(001) substrate was 16 arcsec, which is comparable with the smallest values ever reported. The photoluminescence linewidth at 10 K is 16 meV. Hall measurements are carried out on undoped, Si-doped, and Be-doped InGaP layers grown with a 2×1 surface reconstruction. The electron mobilities are comparable to similar InGaP/GaAs layers grown by gas-source molecular-beam epitaxy. Undoped InGaP layers grown with a 2×2 reconstruction, however, showed a high resistivity of ≥102 Ω cm at 300 K.
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  • 4
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Ketene Compounds, VI1) Transition Metal-Substituted Ketenes of Molybdenum and Tungsten - Preparation, Reactivity, and Spectroscopic InvestigationsMetal-substituted ketenes of molybdenum and tungsten (η5-C5H5)(CO)[P(CH3)3]2MC(CO)R 2d, 4a, b, e (R = CH3. 1-cyclopenten-1-yl, C6H4CH3-(4), Si(C6H5)3) are formed on treatment of dicarbonyl(η5-cyclopentadienyl)carbyne complexes 1d, 3a, b, e with trimethylphosphine. The cleavage of one phosphine ligand leads in a reversible reaction to η2-ketenyl] compounds (η5-C5H5)(CO)[P(CH3)3]M[O=C=C - R] 5d, 6a, b, e. They add carbon monoxide to give dicarbon] substituted η1ketenes(η5C5H5)(CO)2[P(CH3)3] MC(CO)R (7d. 8a-g. R = CH3. 1-cyclo-penten-1-yl, C6H5, C6H4CH3-(4), Si(C6H5)3 C5H4FeC5H5. C6H2(CH3)3-(2.4.6)). 7d and 8d are also available by direct carbonylation of (η5-C5H5)(CO)[P(CH3)3]M≡C—C6 H4 CH3-(4) The diamagnetic compounds, some of which arc very thermolabile, were characterized In IR. 1H, 13C, and 13P NMR spectroscopy.
    Notes: Metallsubstituierte Ketene von Molybdän und Wolfram (η5-CsH5)(CO)[P(CH3)32MC(CO)R 2d, 4a, b, e(R = CH3. 1-Cyclopenten-1-yl], C6H4CH3-(4), Si(C6H5)3)entstehen bei der Umsetzung der Dicarbonyl(η5-cyclopentadienyl)carbin-Komplexe 1d, 3a, b, e mil Trimethylphosphan. In einer reversiblen Reaktion spalten sie Phosphan ab und gehen hierbei in die η2-Ketenylverbindungen 5d, 6a, b, e über. Diese addieren Kohlenmonoxid, wobei sich dicarbonylsubstituierte η1-Ketene der allgemeinen Art (η5-C5H5)(CO)2[P(CH2)3]MC(CO)R (7d, 8a-g, R = CH3, 1-Cyclopenten-1-yl, C6H5, C6H4CH3-(4), Si(C6H5)3, C5H4FeC5H5,. C6H2(CH3)3-(2,4,6)) bilden. 7d und 8d sind ferner noch durch direkte Carbonylierung von (η5-C5H5)(CO)[P(CH3)3]M ≡C—C6H4CH3-(4) (9d und 10d) zugänglich. Die diamagnetischen, teilweise sehr thermolabilen Komplexe werden durch 1R-, 1H-, 13C- und 31P-NMR-Spektren gesichert.
    Additional Material: 5 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 3377-3380 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition Metal Ketene Compounds, VII. Transition Metal Substituted Ketenes with Chelate LigandsThe title compounds can be obtained by the reaction of either (5) with the chelate ligands (CH3)2P-[CH2]nP(CH3)2 (n = 1-2) or (PF2)2NCH3.
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 2451-2452 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Half Ylide ria Transition Metal ComplexA novel cationic half ylide [Ft2N—C(PMe3)2][BF4] can be obtained by reaction of trimethylphosphine with the cationic carbyne complex [(CO)5CrCNEt2][BF4] followed by cleavage of the metal carbon σ-bond. A mechanism is proposed which suits the experimental facts.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 504-512 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transition Metal Ketene Compounds, VIII. Reduction of Transition Metal-substituted Ketenes to AcetylenesThe reaction of dicarbonyl(η5-cyclopentadienyl)(η1-ketenyl)(trimethylphosphane)molybdenum and -tungsten (1d, 2a-d) with carbon monoxide leads to reduction of the ketene moiety with formation of σ-bonded acetylene compounds (3d, 4a-d). Spectroscopic investigations and labelling experiments indicate a significant participation of the metal and give hints for a possible reaction mechanism.
    Notes: Die Umsetzung von Dicarbonyl(η5-cyclopentadienyl)(η1-ketenyl)(trimethylphosphan)molybdän und -wolfram (1d, 2a-d) mit Kohlenmonoxid führt unter Reduktion des Ketenylliganden zu σ-gebundenen Acetylenverbindungen (3d, 4a-d). Spektroskopische Untersuchungen und Markierungsexperimente sprechen für eine maßgebliche Beteiligung des Zentralmetalls und erlauben Rückschlüsse auf einen Reaktionsmechanismus.
    Additional Material: 5 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 110 (1977), S. 3782-3791 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: η1- and η2-Ketenyl Compounds of TungstenTungsten-substituted ketens of the type (η5-C5H5)(CO)[P(CH3)3] 2 W[C(CO)ar] 2a-d (ar=C6H5, C6H4CH3-(4), C6H4OCH3-(4), C5H4FeC5H5) are formed on treatment of dicarbonyl-(η5-cyclopentadienyl)carbyne tungsten complexes 1a-d with trimethylphosphine. Elimination of one phosphine ligand from 2a-d leads to a further ketene type (η5-C5H5)(CO)[P(CH3)3] W-[OCC-ar] 3a-d, which is also available by the reaction of 1a-d with an equimolar amount of phosphine. The latter way allows also the synthesis of (η5-C5H5)(CO)[P(CH3)3] W[OCC-C6H2(CH3)3-(2,4,6)] (3e) and (η5-C5H5)(CO)[P(C6H5) 3]W[OCC-C6H4CH3-(4)] (3f). The diamagnetic compunds, some of which are very thermolabile, were characterized by IR, 1H, 13C and 31P NMR spectroscopy, and in the case of 2b and 3b by an X-ray analysis.
    Notes: Wolfram-substituierte Ketene des Typs (η5-C5H5)(CO)[P(CH3)3]2W[C(CO)ar] 2a-d (ar=C6H5, C6H4CH3-(4), C6H4OCH3-(4), C5H4FeC5H5) bilden sich bei der Umsetzung von Dicarbonyl(η5-cyclopentadienyl)carbinwolfram-Komplexen 1a-d mit Trimethylphosphin. Die Abspaltung eines Phosphinliganden aus 2a-d führt zu einer weiteren Ketenart (η5-C5H5)(CO)[P(CH3)3]W[OCCar] 3a-d, welche auch auf direktem Weg aus 1a-d mit äquimolarer Menge Phosphin zugänglich ist. Letztere Reaktion erlaubt ferner die Synthese von (η5-C5H5)(CO)[P(CH3)3]W[OCC—C6H2(CH3)3-(2,4,6)](3e) und (η5-C5H5)(CO)[P(C6H5)3]W[OCC—C6H4CH3-(4)] (3f). Die diamagnetischen, teilweise sehr thermolabilen Komplexe wurden durch IR-, 1H-, 13C- und 31P-NMR-Spektren und, im Fall von 2b und 3b, durch eine Röntgenstrukturanalyse gesichert.
    Additional Material: 5 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 180-181 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nitrogen-15 NMR spectra of 11 ketenimines have been taken both at the natural-abundance level of 15N and with the aid of 15N-labeling. The nitrogen chemical shifts are substantially different from those of neutral imines and are upfield, more like those of protonated imines. The results are in accord with significant delocalization of the nitrogen lone-pair. Furthermore, there is a rough parallelism between the 13C shifts of the terminal carbons and the 15N shifts.
    Additional Material: 1 Tab.
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  • 10
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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