Browsing by Author "Massardier, Jean"

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    Electron paramagnetic resonance study of hydrogen atoms trapped in γ-irradiated Y type zeolites exchanged with different cations
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Abou-Kais, Antoine; Vedrine, Jacques C.; Massardier, Jean; Dalmai-Imelik, Gisele
    H atoms trapped after the γ-irradiation at 77 K of Y type zeolites exchanged with different cations have been studied using e.p.r. spectroscopy. The H atom yield is dependent on the acidic structural OH group content and it is postulated that the mechanism of formation and trapping of H atoms follows the following equilibrium: [graphic omitted] The H atom yield is related to the acidity and mobility of the hydrogen of the hydrogen of the hydroxyl groups and to the trapping strength. The trapping strength of H atoms, characterized by the values of both the hyperfine coupling constant with respect to the free H atom, and the activation energy of recombination, is strongly dependent on the nature of the exchanged cation, and follows the sequence K > Na [double greater-than, compressed] Ca > La.
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    Evolution of Adsorbed Species During C2H2 Adsorption on Ni(l 11) in Relation to their Vibrational Spectra
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (07), 1978) Bertolini, Jean-Claude; Massardier, Jean; Dalmai-Imelik, Gisèle
    Acetylene adsorption at room temperature on Ni (111) has been studied by low energy electron diffraction (l.e.e.d.), thermal desorption, work function changes and high resolution electron energy loss spectroscopy (h.r.e.l.s.). The existence of two adsorbed states has been demonstrated depending upon exposure. At low exposure, C2H2 is associatively adsorbed but a large rehybridization occurs, characterized by a carbon–carbon bond order close to 1.15. According to its hybridization state C2H2 should be adsorbed on a triangular site through two σ bonds and one π bond with nickel atoms. With increasing exposure, large modifications occur. In addition to self-hydrogenated species, benzene should be formed as shown by comparison of the vibrational spectra of adsorbed C2H2 and adsorbed C6H6. This conclusion is in agreement with the benzene formation as detected after contact between C2H2 and Ni/SiO2 catalysts with (111) exposed faces.