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  • 1
    Electronic Resource
    Electronic Resource
    Changing photoluminescence intensity from GaAs/Al0.3Ga0.7As heterostructures upon chemisorption of SO2 (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1233-1240 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Chemisorption of SO2 gas molecules onto photowashed GaAs surfaces results in a change in the density of charge at the surface, giving rise to a measurable change in the charge distribution within the semiconductor. We consider the development of a novel semiconductor chemical sensor based on this phenomenon. The intensity of photoluminescence (PL) from metalorganic vapor phase epitaxy grown GaAs/Al0.3Ga0.7As structures at 300 K is used to detect this change in charge distribution. The doping densities and layer thicknesses within these heterostructures are shown to have a profound influence on the relative magnitude of PL intensity and its sensitivity to changes in the density of surface charge brought about by chemisorption of SO2. New analytical and finite element method (FEM) numerical models are derived to quantitatively predict the effect of changing surface charge on the PL intensity from finite thickness heterostructure layers. The PL response from these heterostructures is shown to follow the trends predicted by these models and suggests that the adsorption of SO2 from a 0.6 mol % mixture of SO2 in N2 results in a reduction in the negative surface charge density by 9×109 to 2×1010 cm−2. Simultaneous changes in surface recombination rates due to adsorption are shown (using the FEM model) to have no effect on the PL intensity from the structures studied here. The results are applied to the improvement of signal characteristics from a potential chemical sensor device. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358924
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  • 2
    Electronic Resource
    Electronic Resource
    First experimental results from IBM/TENN/TULANE/LLNL/LBL undulator beamline at the advanced light source : Proceedings of the 5th international conference on synchrotron radiation instrumentation (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 1394-1397 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The IBM/TENN/TULANE/LLNL/LBL Beamline 8.0 at the advanced light source combining a 5.0 cm, 89 period undulator with a high-throughput, high-resolution spherical grating monochromator, provides a powerful excitation source over a spectral range of 70–1200 eV for surface physics and material science research. The beamline progress and the first experimental results obtained with a fluorescence end station on graphite and titanium oxides are presented here. The dispersive features in K emission spectra of graphite excited near threshold, and found a clear relationship between them and graphite band structure are observed. The monochromator is operated at a resolving power of roughly 2000, while the spectrometer has a resolving power of 400 for these fluorescence experiments. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145985
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  • 3
    Electronic Resource
    Electronic Resource
    Near-field scanning optical microscopy investigation of immiscibility effects in In1−xGaxP films grown by liquid phase epitaxy (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 2785-2790 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Near-field scanning optical microscopy (NSOM) and electron probe microanalysis (EPMA) were used to study the topographic and microscopic optical properties of indium–gallium–phosphide (In1−xGaxP) samples grown by liquid phase epitaxy on gallium–arsenide substrates. NSOM imaging found strong and highly localized variations in the photoluminescence (PL) intensity for samples that were highly lattice mismatched with the substrate. The topography and optical features were roughly spatially correlated for these samples. Shifts in the PL peak energy position (by as much as 27 meV) were found during scans across highly mismatched samples, whereas no shifts were seen for In1−xGaxP films with a nearly lattice matched composition. Compositional fluctuations were determined to be the cause of these PL peak energy shifts. EPMA provided corroborating evidence that compositional fluctuations are spatially correlated with the topography. These composition fluctuations arise from the known solid–solid miscibility gap in the In1−xGaxP system at temperatures used for the growth of these samples. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1433184
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  • 4
    Electronic Resource
    Electronic Resource
    Evidence for coupling between hydrodynamic interactions and excluded volume effects in polymer coils (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 5731-5743 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In a side-by-side comparison, the q dependence of the collective internal decay constant ∼(ΔΓ)∼qγ of linear polystyrene in good and theta solvents was determined using photon correlation spectroscopy. The results q2.9 and q3.9 for the theta and good solvents, respectively, correspond to relatively strong hydrodynamic interactions (nondraining) when excluded volume effects are minimal for the compact coil at theta and to relatively weak hydrodynamic interactions (partial draining) when excluded volume effects are manifest in the swollen coil in good solvent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458504
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  • 5
    Electronic Resource
    Electronic Resource
    High temperature photoelectron spectroscopy: A study of U, UO, and UO2 (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 5363-5372 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The He i photoelectron spectrum of atomic uranium has been recorded in the vapor phase. Bands associated with metal (6d)−1, (7s)−1, and (5f)−1 ionizations were observed. The relative intensities of the (6d)−1 and (5f)−1 bands are consistent with computed relative cross sections at the He i energy, whereas the intensity of the (7s)−1 band is larger than expected from computed cross sections, implying enhancement of this feature by autoionization effects. HeI photoelectron spectra have also been recorded for the vapor above a heated equimolar UO2(s)@B:U(s) mixture. By studying the spectra obtained as a function of temperature, bands associated with UO and UO2 were identified and these were assigned using relativistic Hartree–Fock–Slater calculations on these molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455587
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  • 6
    Electronic Resource
    Electronic Resource
    Azetidinone sulfenic acids. Isolation of crystalline sulfenic acids from penicillin sulfoxides and a study of their reactivities (1974)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 96 (1974), S. 1609-1610 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00812a063
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  • 7
    Electronic Resource
    Electronic Resource
    Azetidinone antibiotics. XII. Chemical transformations of penicillins and cephalosporins. Mechanism and stereochemistry of the interconversions of penam and cepham systems (1975)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 97 (1975), S. 3192-3198 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00844a045
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  • 8
    Electronic Resource
    Electronic Resource
    n-GaN surface treatments for metal contacts studied via x-ray photoemission spectroscopy (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 204-206 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The surface chemistry and electronic properties of n-GaN surfaces were studied via x-ray photoemission spectroscopy before and after wet chemical treatments. Shifts of the surface Fermi level were measured with the change in position of the Ga 3d core level peak. HCl treatment of n-GaN led to a 0.9 eV shift of the surface Fermi level toward the conduction band minimum, while KOH treatment led to a 0.3 eV shift of the surface Fermi level toward the valance band maximum. These shifts lead to a reduction in the surface barrier for HCl-treated n-GaN and for KOH-treated p-GaN, potentially improving contact resistance. The changes in surface chemistry indicate that a N (or Ga) deficiency with HCl(KOH) treatment alters the surface state density through the formation of donor (acceptor)-like states. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1430024
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  • 9
    Electronic Resource
    Electronic Resource
    Demonstration of near-field scanning photoreflectance spectroscopy (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1943-1945 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A near-field scanning optical microscope (NSOM) was developed to perform photoreflectance (PR) spectroscopy experiments at high spatial resolution (∼1 μm). Representative PR spectra are shown, along with an image illustrating the capability of observing contrast in images due to the strength of a PR feature. It was found that sufficiently high intensity light from the NSOM tip can produce photovoltages large enough to limit the spatial resolution of the electric field determination by PR. The photovoltage effect is measured as a function of light intensity, and the results are discussed in terms of a simple photovoltage expression. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1312253
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  • 10
    Electronic Resource
    Electronic Resource
    The role of Aeromonas salmonicida extracellular products in the pathology of furunculosis (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 4 (1981), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. The extracellular products (ECP) of Aeromonas salmonicida, prepared by the cellophane overlay method, are lethal to rainbow trout when administered parenterally. Sublethal doses when injected i.p. or i.m. are shown to reproduce all the lesions that have been described in the literature as being associated with furunculosis. In addition, meningitis may be an important feature of furunculosi s and is reproduced by injection of ECP. A serum factor, probably an α-globulin, present in normal serum of rainbow trout, is capable of neutralizing the toxic effects of ECP. The pathology is discussed with reference to the proteolytic and leucocidal properties of the ECP and its effects upon the eosinophilic granular cells which are caused to disperse and degranulate with the possible release of histamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2761.1981.tb01108.x
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