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  • 1
    Electronic Resource
    Electronic Resource
    The bonding of acetonitrile and CH2CN on Ag(110) determined by near edge x-ray absorption fine structure: Evidence for π-donor bonding and azimuthal ordering (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 4338-4345 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Carbon K edge near edge x-ray absorption fine structure (NEXAFS) spectra of adsorbed acetonitrile and reactive intermediates derived therefrom on Ag(110) were studied in order to determine their orientation and bonding to the surface. For both the multilayer and the adsorbed monolayer there is excellent agreement between the spectra of the adsorbed acetonitrile and the gas phase species. For the multilayer coverage the orientation of the acetonitrile molecules is not completely random; the molecules prefer an orientation with their bond axes closer to parallel than perpendicular to the surface. At monolayer coverage acetonitrile bound to the surface is unrehybridized. It is bound with its linear molecular skeleton parallel to the surface and randomly oriented azimuthally. Annealing molecular CH3 CN to 325 K in the presence of coadsorbed atomic oxygen produces a linear CH2 CN surface intermediate, the molecular axis of which is parallel to the surface and perpendicular to the close-packed direction. The C–C and C–N bond lengths are essentially unperturbed from their values in gas phase CH3 CN. Bonding appears to occur between the methylene carbon and the metal, as expected. A broadening of the π* resonance for transition into the π* orbital perpendicular to the surface is interpreted in terms of π-donor bonding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456814
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  • 2
    Electronic Resource
    Electronic Resource
    Polarization effects in the valence and inner-shell spectra of poly(di-n-hexylsilane) (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 5925-5933 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The polarized absorption spectra of oriented films of phase-I and phase-II poly(di-n-hexylsilane), PDHS, have been determined in the visible/UV and in the near-edge regions of the C 1s and Si 1s x-ray ionization potentials. The phase-I absorption band at 360 nm is strongly polarized parallel to the direction of the Si chain, whereas the analog of this band in phase II (317 nm) is only weakly polarized in the same direction; this is consistent with partial trans→gauche isomerization of the Si chain in phase II and delocalization of the excitation in part onto disordered n-hexyl groups. Polarized absorption in the vicinity of the Si 1s ionization limit reveals strong polarization of the discrete and continuum transitions in both phase I and phase II, whereas the equivalent spectra taken in the vicinity of the C 1s limit show strong polarization in phase I but little or no polarization in phase II. The x-ray spectra are interpreted as showing that the Si chain and the n-hexyl groups of the polymer are ordered in phase I and are essentially perpendicular to one another, whereas in phase II the n-hexyl chains are disordered while the Si backbone remains relatively fixed in space. The Si 1s electron-yield spectra also display EXAFS interferences which have been transformed to yield Si–Si and Si–C distances in the polymer of 2.37±0.02 and 1.81±0.03 A(ring), respectively. The various discrete and continuum transitions are assigned according to an orbital model, and the visible/UV thermochromism earlier reported for PDHS is now observed in the Si 1s x-ray near-edge spectrum as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454752
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  • 3
    Electronic Resource
    Electronic Resource
    Orientation of ethylene and propylene on Ag(110) from near edge x-ray adsorption fine structure (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 8379-8382 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The π bond orientation of ethylene and propylene on the clean and atomic oxygen covered Ag(110) surfaces has been determined with near-edge x-ray absorption fine-structure (NEXAFS) measurements. The π system of ethylene is tilted 20±5° and 18±5° from the surface normal for ethylene on the clean and atomic oxygen covered surfaces, respectively. The tilt angle of the π system is 20±5° on the clean surface and 31±5° on the atomic oxygen covered surface. On both the clean and atomic oxygen covered surface, the carbon–carbon double bond in ethylene and propylene appears to form a π-donor type bond with the Ag(110) surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459269
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  • 4
    Electronic Resource
    Electronic Resource
    π bonded intermediates in alcohol oxidation: Orientations of allyloxy and propargyloxy on Ag(110) by near edge x-ray absorption fine structure (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 5316-5322 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The orientation of allyl alcohol (CH2=CHCH2OH), propargyl alcohol (CH 3/4 CCH2OH), and their surface alkoxy groups has been examined on Ag(110) using near edge x-ray absorption fine structure (NEXAFS) measurements. The planes containing the π* orbitals of allyl alcohol and its alkoxy species, allyloxy (CH2=CHCH2O−), are tilted 26±4° and 32±5° from the surface normal, respectively. Allyl alcohol itself shows no azimuthal ordering, but the π* orbital in allyloxy is azimuthally oriented 33±15° from the close-packed direction ([11¯0] azimuth). Propargyl alcohol is randomly oriented on the Ag(110) surface. Its alkoxy group, propargyloxy (CH 3/4 CCH2O−), is strongly oriented with the triple bond axis parallel to the plane of the surface and directed along the [001] azimuth, perpendicular to the troughs. The position of the σ* resonances indicate that no loss of the allylic hydrogen has occurred and that the double and triple bonds are slightly, but not significantly, perturbed from their normal gas phase bond lengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455622
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  • 5
    Electronic Resource
    Electronic Resource
    Orientation and absolute coverage of furan and 2,5-dihydrofuran on Ag(110) determined by near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 4012-4023 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The orientation, absolute coverage and core-electron binding energies of furan (C4H4O) and 2,5-dihydrofuran (C4H6O) on Ag(110) have been measured using near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy. Both furan and 2,5-dihydrofuran (2,5-DHF) are tilted 22±7° from the plane of the surface for both submonolayer and monolayer coverages. The saturation monolayer coverages on the Ag(110) surface of 0.45±0.07 ML for furan and 0.41±0.06 ML for 2,5-DHF are consistent with expectations based on van der Waals radii. The C(1s) binding energies for a monolayer of furan on Ag(110) are 284.8 and 286.2 eV, while the C(1s) binding energies for 2,5-DHF are 285.1 and 286.6 eV. The O(1s) binding energies are 532.8 and 533.8 eV for furan and 2,5-DHF monolayers, respectively. The onset of excitations from C(1s) levels to the continuum lies well above the Fermi level due to the weak bonding interactions with the surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460678
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  • 6
    Electronic Resource
    Electronic Resource
    Inositol Trisphosphate Mobilizes Intracellular Calcium in Permeabilized Adrenal Chromaffin Cells (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 46 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Using permeabilized chromaffin cells and the fluorescent probe Quin 2 (an indicator of free Ca2+), we found that inositol trisphosphate (IP3) specifically triggered an immediate and dose-dependent release of Ca2+ from intracellular stores. Desensitization of the response was observed at nonsaturating concentrations of inositol trisphosphate and resequestration of Ca2+ was not observed. While representing only a small fraction of the total cellular Ca2+, the amount released by IP3 could significantly raise cytosolic Ca2+ and may account for muscarinic effects on Ca2+ metabolism in chromaffin cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb13014.x
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  • 7
    Electronic Resource
    Electronic Resource
    Managing Drug Interactions With Oral Contraceptives (1983)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of obstetric, gynecologic and neonatal nursing 12 (1983), S. 0 
    Details
    ISSN: 1552-6909
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: An increasing concern to nurses is the possibility of drug interactions involving oral contraceptives. Information regarding the mechanisms, significance, and management of drug interactions with oral contraceptives is provided. Approaches to counseling patients also are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1552-6909.1983.tb01082.x
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  • 8
    Electronic Resource
    Electronic Resource
    X-ray magnetic circular dichroism studies of multilayered thin films of 3d transition metals (invited) (abstract) : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5807-5807 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray magnetic circular dichroism (XMCD) is used to probe both the spin and orbital d moments of Co in Co/Pd, Co/Pt, and Co/Ni multilayers, and in a Au/Co-wedge/Pd structure. While the spin moment per Co atom is found to be constant within the experimental error, the orbital moment shows a strong dependence both on the chemical environment and on the thickness of the Co layer. In particular, we find an orbital moment enhancement of up to a factor of three for a Co layer thickness of four atomic layers in the present Au/Co/Pd sandwich structure. This enhancement decays to the bulk Co value, roughly following a 1/dCo dependence, thus confirming its interfacial origin. The relevance of these observations with respect to the perpendicular magnetic anisotropy in these samples will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355571
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  • 9
    Electronic Resource
    Electronic Resource
    Element specific magnetic microscopy with x rays (invited) (abstract) : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6890-6890 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used the magnetic circular x-ray dichroism (MCXD) technique to image magnetic domains with a spatial resolution of 1 μm. The experiments employed circularly polarized soft x rays near the edges of the three-dimensional (3d) transition metals Co ((approximately-equal-to)780 eV) and Ni ((approximately-equal-to)850 eV) and a photoemission microscope based on an electrostatically imaging lens system. Element specific contrast is obtained by tuning to a specific L edge resonance ("white line'') and imaging the number of secondary electrons created locally near the surface of the sample. The magnetic contrast arises from the fact that the white line intensity depends on the relative orientation of the photon spin and the local magnetization direction. The obtained contrast is remarkably large ((approximately-equal-to)20%) such that images can be recorded without background subtraction. Images taken at the L3 and L2 resonance energies give reversed contrast, as expected. Because of the long x-ray and secondary electron mean free paths, images can be recorded for buried magnetic layers which makes this new technique especially valuable for technological applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356822
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  • 10
    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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