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  • 1990-1994  (8)
  • 1985-1989  (4)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 3353-3362 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Clean polyimide films spin-coated onto gold substrate have been fully characterized by high resolution electron energy loss spectroscopy (HREELS): 19 electron-induced vibrational bands could be resolved and assigned by comparison with IR spectroscopy. The attribution of these peaks constitutes a firm and necessary basis for the detailed study of the incipient interface formation with aluminum at room temperature. The metal being evaporated at a low rate from a Knudsen effusion cell, its equivalent coverage on the polymer could be monitored very efficiently and allowed a clear distinction between three reaction steps: (i) at an Al coverage below 4×1014 Al atom/cm2, the aluminum atoms interact only with the C–O carbonyl in the polymer to form a C–O–metal complex; (ii) between 4 and 10×1014 atom/cm2, no further Al "reaction'' occurs, but the appearance of new CH and OH stretching bands is attributed to bond breaking in the polymer and diffusion of the residues towards the surface; (iii) after further metal evaporation, all the peaks reduce in intensity and the observation of a ν(Al–O) [or ν(Al–C) band] testifies the formation of an aluminum oxide (or carbide) at the surface. Although no dedicated theory can be invoked up to now for the interpretation of HREELS data collected with different electron impact energies and under different scattering geometries, the spectra measured from polyimide before and after aluminum condensation are consistent with a modification of the geometry of the polymer monomeric unit after bonding with the metallic atoms. The metallized polymer surface appears with an equal statistical spatial distribution of all the chemical groups.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ablation of poly(ethylene terephthalate) (PET) by Ar-F laser radiation has been studied at different fluences for amorphous and semicrystalline samples by scanning electron microscopy (SEM) and by etch-depth measurements. The surface structure created on PET has been interpreted as resulting mainly from a difference in the etch rate—and not the ablation threshold—between amorphous and semicrystalline PET. SEM pictures clearly show the melting of the PET surface at high fluence (≥80 to 100 mJ/cm2) and not below that value. UV laser etching is proposed as a quick and easy method for observing the crystalline subsurface structure of aromatic semicrystalline polymers, as long as low fluence and a low pulse repetition rate are used.
    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 101 (1994), S. 781-787 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron-induced vibrational spectra of four poly(amino acid)s—poly-alanine, poly-leucine, poly-methionine, and poly(benzyl-aspartate)—have been recorded. After discussing the surface sensitivity of the technique and the excitation mechanisms of the molecular vibrations, it is concluded that high resolution electron energy loss spectroscopy (HREELS) spectra are dominated by vibrational bands fingerprinting the polymer sidechains. From these observations, suggestions are made on the molecular conformation at the surface of these poly(amino acid)s films.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 6452-6457 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Surfaces of polyethylene and n-hexatriacontane were for the first time studied by high resolution electron energy loss spectroscopy (HREELS). The vibrational band energies and intensities were recorded and compared to transmission infrared data. The attribution of most of the bands to methyl, methylene, and C–C vibrations is straightforward; but some of the bands remain unassigned. The intensities of the methyl associated electron energy losses are greatly enhanced. This confirms the extreme surface sensitivity of the spectroscopy and is consistent with a C–C skeleton preferentially oriented perpendicular to the surface. Measured cross section data vs electron impact energy (E0) show that while a dipolar-type interaction mechanism is dominating some regions of the cross-section curve, other resonance scattering may contribute significantly for low and high E0. This cross-section curve shows also that the polymer surfaces are to be considered as a "condensed gas,'' with weak intermolecular interaction, instead of a real solid state material with collective (phonon) vibrational excitations. No evidence of radiation damage could be found in the vibrational spectra.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0630
    Keywords: 68.55.−a ; 73.60.−n ; 79.20.Kz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract C60 films have been grown in ultra high vacuum on various crystalline substrates and the structure of the films has been investigated by low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS). The C60 films form randomly oriented nanocrystals on Si(100), mesoscopic polycrystals on GaSe(0001) and microscopic single crystals on GeS(001). The vibrational structure of the C60/substrate interfaces is analyzed in detail by HREELS carried out in the dipole and impact scattering regimes. It is shown that the epitaxy of C60 on GeS(001) is induced by the weak van der Waals bonding and the peculiar corrugation of the substrate surface.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 329 (1987), S. 370-373 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interface formation between Sb(111) single crystals and evaporated indium has been studied with various spectroscopic techniques. It is shown from an Auger intensity analysis that a layer-growth of InSb is obtained at 550 K. LEED is used to determine the overlayer atomic geometry. The InSb layer is ordered and a lattice parameter close to the value for InSb(111) is obtained. The InSb formation is confirmed by the chemical shift of the Sb 4d and In 4d core lines with XPS.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 446-451 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We have studied the formation of the Cu/MgO interface with Auger electron spectroscopy and high-resolution electron energy-loss spectroscopy (HREELS). Copper overlayers ranging in thickness from 1 to 20 Å were formed on an MgO single- crystal substrate by evaporation from a Knudsen effusion cell. Direct Auger spectra for the O KLL, Cu LMM and Mg KLL lines were collected. The evolution of the Auger peak intensities shows that the copper initially forms a complete monolayer, followed by island formation (i.e. Stransky-Krastanov growth). Low energy electron diffraction patterns recorded after Cu deposition confirmed the ordering of the first monolayer.A significant decrease in energy of the surface MgO phonon peak was observed by HREELS following deposition of 20 Å of copper. Simultaneously with this shift of the phonon energy, we observed a decrease of the intensity ratio of the phonon-loss and elastic peaks. These results have been interpreted using the dielectric theory. Theoretical spectra of MgO covered by a layer of Cu2O obtained by using dielectric constants taken from the literature were able to reproduce qualitatively the decreases in energy and intensity of the phonon-loss peak with increasing copper thickness.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 609-613 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two cases of water interaction with virgin PET and with metallized (Al) PET were studied using thermal desorption spectroscopy (TDS) and dynamic secondary ion mass spectrometry (SIMS), respectively. On the one hand, the TDS approach tends to show that the water is weakly bound to the polyester (∼ 10 kcal mol-1); on the other hand, the SIMS study performed on metallized PET shows an enhancement of the water concentration around the interface. These results are discussed in order to elucidate the presence of such moisture and its influence on the metal/polymer adhesion and corrosion.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 193-196 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We have studied by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) the room temperature growth of aluminium nitride (AlN) at the surface of clean and oxidized polycrystalline iron. The films were deposited by reactive rf-sputtering in an N2-Ar atmosphere. Very low coverages were possible thanks to a precise partial pressure controller based on electron impact emission spectroscopy (EIES).The AlN/Fe interface study has revealed the formation of an iron nitride at the surface of the substrate and of a compound close to AlN as a first monolayer. AlN clusters grow directly on this nitride layer and we did not detect the formation of any alloy between iron and aluminium. A modelization of the AES signal intensities suggests a Stranski-Krastanov growth mode.For the oxidized iron, Auger lines showed an Fe2O3 surface layer on an Fe3O4 film oxide. The former oxide was reduced to Fe3O4 by the incoming aluminium which forms a two-phase film made of Al2O3 and AlN resulting in an (AlN)x(Al2O3)1-x stoichiometry. The concentration of this oxide phase decreases after the diffusion of the oxygen stops. Pure AlN begins to grow on this two-phase film.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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