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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 8725-8731 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: X-ray absorption measurements at the Ru L3 edge have been used to study the adsorption of Ru3(CO)12 on Cu(100) surfaces at submonolayer and monolayer coverages and the subsequent formation of Ru–Cu bimetallic aggregates at these surfaces. The analysis of the Ru L3 edge x-ray absorption near edge structure (XANES) reveals (a) the surface Ru–Cu bimetallic aggregates are three dimensional clusters of which the Ru atoms are in the "bulk'' and the surface of the cluster is covered with Cu atoms, and (b) relative to pure Ru metal, Ru in the bimetallic aggregates gains d character. The chemical properties of these bimetallic surfaces and the effect of the cluster size on their electronic properties revealed by XANES as well as LEED and Auger are also reported. These results are compared with previous results of Ru3(CO)12/Cu(111). The implications of these observations are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 95 (1991), S. 7636-7641 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 803-807 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The chemical structure and property of fluorine-containing species on the hydrofluoric acid (HF) etched Si surface was examined by use of x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The fluorine content on the surface was found to increase with increase of HF concentration. A silicon surface etched by 50% HF has fluorine of 2.6×1014 atoms/cm2 as Si–F. Most of the Si–F bondings are rapidly hydrolyzed to Si–OH by rinsing the wafer in water. Thus prepared Si–OH groups are found to be useful as active sites for chemical modification of the bare silicon single-crystal surface. The Si–F was observed not to influence the oxidation rate of HF etched silicon surface.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 237-240 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Vacuum evaporation of a merocyanine dye, 3-ethyl-5 [2-(3-ethyl-2-benzothiazolidene) ethyldene]-2-thioxo-4-thiazolidione, onto different substrates such as bare and surface-oxidized silicon wafers and a quartz glass substrate is done. There is a difference in color between a film deposited on the bare silicon substrate and one on either a quartz glass plate or a silicon wafer with a thick (96.5-nm) oxide layer. The dye film on quartz has an absorption maximum at 560 nm, whereas that on bare silicon has one at 582 nm. The bare crystalline silicon surface may give dye molecules more opportunity to aggregate than amorphous silicon dioxide or quartz surfaces. The dye molecules are preferentially oriented along the [100] direction of the substrate crystal, with the carbonyl group parallel to and the conjugated aromatic plane perpendicular to the substrate surface, although there is no detectable difference of orientation between the films deposited on these different substrates.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2890-2893 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamondlike carbon films were prepared by electron cyclotron resonance chemical vapor deposition. Structures of the carbon films were characterized by Raman spectroscopy and Fourier-transform infrared spectroscopy. The relationship between the properties of films and growth conditions has been examined. High-energy ion species extracted from a discharge of methane in the electron cyclotron resonance cavity, which is positively-biased electrically against the earthed substrate, have an important role in the growth behavior of hard diamondlike carbon films.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2187-2191 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A technique is developed to control the chemical reactivity of a silicon single-crystal surface through chemical modification with atomic hydrogen. The reactivity of the reconstructed single-crystal surface prepared by high-temperature treatment in an ultrahigh vacuum is significantly decreased by capping the dangling bonds of top-layer silicon atoms with hydrogen atoms. The Si—H bonds on the hydrogenated surface are found to be much more stable against oxidation than the Si—Si back bonds. The hydrogen-passivated silicon surface is reactivated by electron beam irradiation. An ultrathin oxide layer pattern can be prepared using preferential oxidation of the area reactivated by a focused electron beam.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 1 (1994), S. 91-94 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The use of surface XAFS for exploring new aspects of the structural study of the adsorption of atoms and molecules on solid surfaces is discussed. Three examples are considered: the chemisorption at step sites, the dynamical properties of the bonding between ad-atoms and substrates, and the adsorption of organic molecules on metal surfaces.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 87 (1992), S. 559-569 
    ISSN: 1435-1803
    Keywords: Cardioplegicsolution ; cardiacarrest ; ischemicinjury ; magnesium ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cardioprotective effects of magnesium and calcium in hyperkalemic cardioplegic solutions were investigated in isolated rat hearts. Isolated rat hearts were arrested for 30 min at 37°C in cardioplegic solutions containing magnesium and calcium in varying concentrations. In St. Thomas' Hospital cardioplegic solution, the magnesium and calcium concentrations were varied as follows: Mg 0; Ca 0.1, 0.3, 0.6, 1.2 mmol/l (mM)./ Mg 4; Ca 0.1, 0.3, 0.6, 1.2 mM./ Mg 8; Ca 0.1, 0.3, 0.6, 0.9, 1.2 mM./ Mg 12; Ca 0.1, 0.6, 0.9, 1.2 mM./ Mg 16; Ca 0.1, 0.6, 1.2, 1.5 mM. For each magnesium concentration, the percentage recovery of aortic flow generated dose-response curves depending on calcium concentration. The maximum percentage recovery of aortic flow was 76.0%±2.7% (mean ±SEM) in the Mg0−Ca0.1 mM group, 77.1%±2.0% in the Mg4−Ca0.3 mM group, 78.5%±2.3% in the Mg8−Ca0.6 mM group, 79.8%±2.4% in the Mg12−Ca0.9 mM group and 80.0%±3.4% in the Mg16−Ca1.2 mM (ST solution) group. Significant difference in the recovery of aortic flow has not been observed among these groups, and furthermore, significant differences in the recovery of other parameters of cardiac function and Ck leakage have not been observed among these groups. These results suggest that the cardioprotective effects depend on the relative combination of magnesium and calcium concentrations, and that it is important to maintain an appropriate balance of magnesium and calcium in hyperkalemic cardioplegic solutions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-879X
    Keywords: PtRh bimetallic catalysts ; EXAFS ; CO-O2 reaction ; CO-NO reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract PtRh bimetallic particles, evidenced by EXAFS at Pt L3-edge and Rh K-edge, were prepared in the supercages of NaY zeolites. Bimetallic catalysts, PtRh/NaY, were more reactive in CO-O2 and CO-NO reactions than their corresponding monometallic catalysts, Pt/NaY and Rh/NaY.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Counter-current extraction ; Chiral resolution ; Ofloxacin enantiomers ; Aqueous two-phase system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The partial resolution of some drug enantiomers by counter-current extraction in an aqueous two-phase system using bovine serum albumin (BSA) or ovomucoid (OVM) as chiral discriminator is described. The phase system was prepared with dextran 40, polyethylene glycol and a protein. Ofloxacin (OFLX) enantiomer was well recognized by the BSA system, whereas the enantiomers of carvedilol (β-blocker) and DG-5128 (a new oral hypoglycaemic drug) were hardly recognized by the OVM system. The distribution coefficients of (S)-, (R)- and rac-OFLX varied with pH. Good enantioselectivity for OFLX was obtained at relatively high pH (≥ pH 9). The crude optically enriched OFLX enantiomers were extracted from the aqueous fractions and finally purified by thin-layer chromatography.
    Type of Medium: Electronic Resource
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