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  • 1
    Electronic Resource
    Electronic Resource
    Nonlinear spectroscopy near half-gap in bulk and quantum well GaAs/AlGaAs waveguides (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1927-1935 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the nonlinear properties of bulk AlGaAs and GaAs/AlGaAs multiple quantum wells (MQW) below the half-band-gap energy using subpicosecond pulses between 1.65 and 1.7 μm. In the bulk material we find a value for the nonlinear index n2 = +3.6× 10−14 cm2/W and a two-photon absorption coefficient β = 0.26 × 10−4 cm/MW. In the MQW we measure an n2 up to 2.4 times larger, and we attribute this enhancement to a stronger 1S-exciton intermediate state. The β value is up to 25 times larger in the MQW. This larger value may result from midgap states that resonantly enhance the virtual intermediate state in two-photon absorption and act as a real transition in a two-step absorption process. The resulting figure of merit (2n2/βλ) for the bulk (MQW) material is 17 (1.6), which means that these semiconductors below half band gap are appropriate for all-optical switching and quantum optics applications. We confirm that n2 is instantaneous on the 300 fs time scale of our pulses from self-phase-modulation spectra as well as time-resolved pump-probe measurements. However, we find an intriguing exchange of energy between the two orthogonal axes as evidenced by the signal along the probe axis following the negative derivative of the pump intensity. This result may be explained by self-phase modulation of the pump combined with a low-frequency Raman process that couples the modes along orthogonal axes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351182
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  • 2
    Electronic Resource
    Electronic Resource
    Low-threshold GaAs/AlGaAs quantum-well lasers grown by organometallic vapor-phase epitaxy using trimethylamine alane (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 432-435 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have utilized a new aluminum source, trimethylamine alane (TMAA), in the growth of graded-index separate-confinement heterostructure single quantum-well GaAs/AlGaAs laser structures by low pressure (30 Torr) organometallic vapor-phase epitaxy. We find lower carbon and oxygen incorporation in AlGaAs epilayers using TMAA since it does not contain a direct Al–C bond and it is not susceptible to the formation of volatile Al–O containing compounds. The oxygen and carbon concentrations were below the detection limits (〈 5 × 1016 cm−3 and 〈 3 × 1016 cm−3, respectively) of the secondary ion mass spectrometry measurements. Broad-area lasers with 10-nm quantum wells and Al0.45Ga0.55As cladding layers exhibited threshold current densities of 140 A cm−2 for cavity lengths of 1 mm, internal quantum efficiencies of 81%, and intrinsic losses of 1.6 cm−1. These results demonstrate that extremely high-quality AlGaAs and GaAs quantum wells can be grown with TMAA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350294
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  • 3
    Electronic Resource
    Electronic Resource
    Calculated structures for [001] symmetrical tilt grain boundaries in silicon (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2048-2056 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structures of [001] tilt boundaries in silicon have been systematically investigated by computer modeling, using the harmonic Keating potential to describe the interatomic forces. The full angular range of symmetrical tilt boundaries can be described in terms of linear combinations of characteristic groupings of atoms. More than one stable relaxed structure has been found for most grain boundaries. In all cases the relaxed bicrystal consists of localized groups of pure edge or 45° dislocation cores embedded in a tetrahedrally coordinated, stable structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348730
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  • 4
    Electronic Resource
    Electronic Resource
    Tip-sample interaction in a "shear-force" near-field scanning optical microscope (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3609-3613 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The interaction between the tip of a near-field scanning optical microscope (NSOM) and the sample it scans is analyzed and compared to a simple tapping model. The approach curves acquired with the NSOM are in excellent agreement with the model, and additional experiments strongly point against a noncontact interaction (such as shear force). Based on this model we are also able to explain the oscillations pattern of the feedback loop. We conclude that our straight-fiber tip, operating under "shear-force" control, intermittently contacts the surface it is scanning, in a way similar to the tapping mode in atomic force microscope. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149967
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  • 5
    Electronic Resource
    Electronic Resource
    Tissue-Specific Processing of the Neuroendocrine Protein VGF (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 65 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: VGF is a neuroendocrine-specific gene product that is up-regulated by nerve growth factor in the PC12 cell line. In rat neuroendocrine tissues two polypeptides of 90 and 80 kDa were detected by an antiserum to an N-terminal domain of VGF (from residues 4 to 240). In parallel, an antiserum directed against the C-terminal nonapeptide of VGF (from residues 609 to 617) revealed several additional posttranslational products. Peptides of apparent molecular sizes of 20, 18, and 10 kDa were prominent in nerve tissues and the hypophysis but absent in the adrenal medulla, and their relative abundance varied in distinct regions of the CNS. In PC12 cells VGF was proteolytically processed only after nerve growth factor treatment, and primary cultures of rat cerebellar granule cells accumulated the low-molecular-weight forms of VGF during in vitro maturation. In these cells the specific cleavages of VGF occurred in a postendoplasmic reticulum compartment; the processed forms were enriched in the secretory vesicles and were preferentially secreted upon cell membrane depolarization. Distinct differential distribution in the CNS and in vitro release of such posttranslational products indicate that these species may represent biologically relevant forms of VGF that play a role in neuronal communication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.65062441.x
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of the Thermal Isomerization of Bicyclo[2.1.1]hexane1 (1963)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 85 (1963), S. 3363-3365 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00904a011
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  • 7
    Electronic Resource
    Electronic Resource
    The spectrum of microdisk lasers (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 644-653 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A model for quantitative analysis of microdisk laser emission spectra is presented. Conformal mapping is used to determine radial and azimuthal eigenvalues, eigenvectors, and cavity Q corresponding to leaky optical resonances in an optically transparent dielectric disk. The effects of gain and loss in a microcavity active medium are also included in the model. Our results compare well with experimental data obtained from an InGaAs/InGaAsP quantum well microdisk laser of radius R=0.8 μm. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362873
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  • 8
    Electronic Resource
    Electronic Resource
    Asymmetric line broadening in intracavity loss modulated quantum well distributed feedback lasers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 669-671 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report for the first time high-speed (Gbit s−1), single mode, digital (on-off) modulation of intracavity loss modulated 1.55 μm InGaAs/InP multiple quantum well distributed feedback lasers. The lasing spectrum, observed to be asymmetrically broadened under high-speed modulation, is shown to result from large carrier density variations which accompany this switching scheme. We also show, for the first time, digitally current-modulated lasers have broader linewidths than devices which use intracavity loss modulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104563
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  • 9
    Electronic Resource
    Electronic Resource
    Si(100)-(2×1)boron reconstruction: Self-limiting monolayer doping (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2779-2781 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A (2×1) surface reconstruction distinct from the clean Si(100)-(2×1) surface is formed by depositing boron onto silicon in ultrahigh vacuum. Overgrowth of epitaxial silicon at low temperature preserves a (2×1) superstructure of substitutional boron. Hall-effect measurements at 4.2 K show complete electrical activity for boron coverages of 1/2 monolayer, but additional boron above 1/2 monolayer is not electrically active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103785
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  • 10
    Electronic Resource
    Electronic Resource
    Human substance P receptor (NK-1): organization of the gene, chromosome localization and functional expression of cDNA clones (1991)
    s.l. : American Chemical Society
    Biochemistry 30 (1991), S. 10640-10646 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00108a006
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