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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 34 (1962), S. 1587-1590 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 34 (1962), S. 164-166 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 9622-9636 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reaction between ground state carbon atoms, C(3Pj), and 1,3-butadiene, H2CCHCHCH2, was studied at three averaged collision energies between 19.3 and 38.8 kJmol−1 using the crossed molecular beam technique. Our experimental data combined with electronic structure calculations show that the carbon atom adds barrierlessly to the π-orbital of the butadiene molecule via a loose, reactantlike transition state located at the centrifugal barrier. This process forms vinylcyclopropylidene which rotates in a plane almost perpendicular to the total angular momentum vector J around its C-axis. The initial collision complex undergoes ring opening to a long-lived vinyl-substituted triplet allene molecule. This complex shows three reaction pathways. Two distinct H atom loss channels form 1- and 3-vinylpropargyl radicals, HCCCHC2H3(X2A″) and H2CCCC2H3(X2A″), through tight exit transition states located about 20 kJmol−1 above the products; the branching ratio of 1- versus 3-vinylpropargyl radical is about 8:1. A minor channel of less than 10% is the formation of a vinyl, C2H3(X2A′), and propargyl radical C3H3(X2B2). The unambiguous identification of two C5H5 chain isomers under single collision has important implications to combustion processes and interstellar chemistry. Here, in denser media such as fuel flames and in circumstellar shells of carbon stars, the linear structures can undergo a collision-induced ring closure followed by a hydrogen migration to cyclic C5H5 isomers such as the cyclopentadienyl radical—a postulated intermediate in the formation of polycyclic aromatic hydrocarbons (PAHs). © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 9637-9648 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reaction of ground state carbon atoms, C(3Pj), with dimethylacetylene, H3CCCCH3, was studied at three collision energies between 21.2 and 36.9 kJmol−1 employing the crossed molecular beam approach. Our experiments were combined with ab initio and RRKM calculations. It is found that the reaction is barrierless via a loose, early transition state located at the centrifugal barrier following indirect scattering dynamics through a complex. C(3Pj) attacks the π system of the dimethylacetylene molecule to form a dimethylcyclopropenylidene intermediate either in one step via an addition to C1 and C2 of the acetylenic bond or through an addition to only one carbon atom to give a short-lived cis/trans dimethylpropenediylidene intermediates followed by ring closure. The cyclic intermediate ring opens to a linear dimethylpropargylene radical which rotates almost parallel to the total angular momentum vector J. This complex fragments to atomic hydrogen and a linear 1-methylbutatrienyl radical, H2CCCCCH3(X2A″), via a tight exit transition state located about 18 kJmol−1 above the separated products. The experimentally determined exothermicity of 190±25 kJmol−1 is in strong agreement with our calculated data of 180±10 kJmol−1. The explicit verification of the carbon versus hydrogen exchange pathway together with the first identification of the H2CCCCCH3 radical represents a third pathway to form chain C5H5 radicals in the reactions of C(3Pj) with C4H6 isomers under single collision conditions. Previous experiments of atomic carbon with the 1,3-butadiene isomer verified the formation of 1- and 3-vinylpropargyl radicals, HCCCHC2H3(X2A″), and H2CCCC2H3(X2A″), respectively. In high-density environments such as combustion flames and circumstellar envelopes of carbon stars, these linear isomers can undergo collision-induced ring closure(s) and/or H atom migration(s) which can lead to the cyclopentadienyl radical. The latter is thought to be a crucial reactive intermediate in soot formation and possibly in the production of polycyclic aromatic hydrocarbon molecules in outflow of carbon stars. Likewise, a H atom catalyzed isomerization can interconvert the 3-vinylpropargyl and the 1-methylbutatrienyl radical. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Crossed molecular beam experiments were conducted to investigate the reaction of ground state carbon atoms, C(3Pj), with 1,2-butadiene, H2CCCH(CH3) (X 1A′), at three collision energies of 20.4 kJ mol−1, 37.9 kJ mol−1, and 48.6 kJ mol−1. Ab initio calculations together with our experimental data reveal that the reaction is initiated by a barrier-less addition of the carbon atom to the π system of the 1,2-butadiene molecule. Dominated by large impact parameters, C(3Pj) attacks preferentially the C2–C3 double bond to form i1 (mechanism 1); to a minor extent, small impact parameters lead to an addition of atomic carbon to the C1–C2 bond yielding i2 (mechanism 2). Both cyclic intermediates i1 and i2 ring open to triplet methylbutatriene complexes i3′ (H2CC*CCH(CH3)) and i3″, (H2CCC*CH(CH3)); C* denotes the attacked carbon atom. i3′ is suggested to decay nonstatistically prior to a complete energy randomization via atomic hydrogen loss forming 1- and 4-methylbutatrienyl CH3CCCCH2 (X 2A″) and HCCCCH(CH3) (X 2A″), respectively. The energy randomization in i3″ is likely to be complete. This isomer decomposes via H atom loss to 3-vinylpropargyl, H2CCCC2H3(X 2A″), as well as 1- and 4-methylbutatrienyl radicals. In high-density environments such as the inner regions of circumstellar envelopes of carbon stars and combustion flames, these linear C5H5 isomers might undergo collision induced isomerization to cyclic structures like the cyclopentadienyl radical. This isomer is strongly believed to be a key intermediate involved in the production of polycyclic aromatic hydrocarbon molecules and soot formation. These characteristics make the reactions of atomic carbon with C4H6 isomers compelling candidates to form C5H5 isomers in the outflow of AGB stars and oxygen-deficient hydrocarbon flames. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 63 (1998), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Phase transfer experiments were performed, involving contact between an aqueous 1:1 solution of α-lactalbumin and β-lactoglobulin and an AOT-in-isooctane reversed micellar phase. The resulting extraction and separation of the two proteins were analyzed as functions of pH, ionic strength and total protein concentration using SDS-PAGE, and compared with extractions from pure solutions. At low protein concentrations, the extent of reversed micellar solubilization of the two pure proteins predicted well the extraction from mixtures. However, at higher protein concentrations β-lactoglobulin appeared to be excluded from the micellar droplets. Because of the significantly different partitioning behavior of the two proteins, reversed micellar extraction from an initially equal weight mixture led to an effective separation of the proteins.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3928-3932 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Defect levels in n-type Si Schottky barrier diodes made by resistive evaporation have been investigated by deep level transient spectroscopy. Three defect levels are observed at 0.16, 0.14, and 0.12 eV below the conduction band. The concentrations of the defect levels exponentially decrease into the substrate. The defects are introduced during etching process rather than evaporation process. The concentration of the defects increase with the thickness of the layer removed by etching before Schottky metal deposition, and decrease with the etching rate. This suggests that the defect levels are produced near the surface and are driven into the substrate during etching processes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2322-2324 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Lattice-matched InGaP/GaAs superlattices have been grown by gas-source molecular beam epitaxy. High-resolution images obtained with transmission electron microscopy reveal the superlattices to be free of dislocations and to exhibit smooth interfaces of only 1–2 monolayers in width. Double crystal x-ray diffraction studies indicate that the narrow interfacial regions are locally strained as a result of the growth sequence during gas-source molecular beam epitaxy.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 140-142 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth of single-crystal InP films on (100) Si substrates by molecular beam epitaxy (MBE) is described. Three different buffer layers were grown by gas-source MBE in order to reduce the density of dislocations created by the 8% InP-Si lattice mismatch. Double-crystal x-ray diffraction revealed that all buffer layers produced large-area single-crystal (100) InP films with the InP lattice tilted towards the 〈100〉 Si directions. A buffer layer of four Inx Ga1−x P/Iny Ga1−y P strained superlattices produced a specular InP film with an estimated dislocation density of 108 –109 cm−2 and a residual stress of less than 5×10−4.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1016-1018 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial layers of InSb have been grown on Si substrates by molecular beam epitaxy. Room-temperature electron mobilities are 48 000 and 39 000 cm2/V s for 3.2 μm-thick InSb with and without a thin GaAs buffer, respectively. The corresponding carrier concentrations are 2.2×1016 and 2.7×1016 cm−3. A sample with an InSb thickness of 8 μm exhibited room-temperature mobilities as high as 55 000 cm2/V s with carrier concentrations of about 2.0×1016 cm−3. A sharp band-edge transmission spectrum is observed at room temperature for the 8 μm layer.
    Type of Medium: Electronic Resource
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