NEXAFS studies of complex alcohols and carboxylic acids on the Si(111)(7×7) surface

Outka, Duane A.; Stöhr, J.; Madix, R. J.; Rotermund, Harm Hinrich; Hermsmeier, B.; Solomon, J. L.

doi:10.1016/s0039-6028(87)80613-1

Cited by 122 publications

(82 citation statements)

References 29 publications

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“…R 3 was assigned to a C-O r* resonance, in agreement with assignments published by Outka et al [35] and Ishii and Hitchcock [36] for methanol multilayers. Lindner et al found a significant dependence of the R 3 intensity on the light incidence angle which led them to the conclusion that the C-O molecular axis is oriented parallel to the surface normal in the investigated case.…”

Section: Electron Spectroscopy Datasupporting

confidence: 87%

Methanol Adsorption on V2O3(0001)

et al. 2011

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Well ordered V 2 O 3 (0001) layers may be grown on Au (111) surfaces. These films are terminated by a layer of vanadyl groups which may be removed by irradiation with electrons, leading to a surface terminated by vanadium atoms. We present a study of methanol adsorption on vanadyl terminated and vanadium terminated surfaces as well as on weakly reduced surfaces with a limited density of vanadyl oxygen vacancies produced by electron irradiation. Different experimental methods and density functional theory are employed. For vanadyl terminated V 2 O 3 (0001) only molecular methanol adsorption was found to occur whereas methanol reacts to form formaldehyde, methane, and water on vanadium terminated and on weakly reduced V 2 O 3 (0001). In both cases a methoxy intermediate was detected on the surface. For weakly reduced surfaces it could be shown that the density of methoxy groups formed after methanol adsorption at low temperature is twice as high as the density of electron induced vanadyl oxygen vacancies on the surface which we attribute to the formation of additional vacancies via the reaction of hydroxy groups to form water which desorbs below room temperature. Density functional theory confirms this picture and identifies a methanol mediated hydrogen transfer path as being responsible for the formation of surface hydroxy groups and water. At higher temperature the methoxy groups react to form methane, formaldehyde, and some more water. The methane formation reaction consumes hydrogen atoms split off from methoxy groups in the course of the formaldehyde production process as well as hydrogen atoms still being on the surface after being produced at low temperature in the course of the methanol ? methoxy ? H reaction.

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Section: Electron Spectroscopy Datasupporting

confidence: 87%

Methanol Adsorption on V2O3(0001)

et al. 2011

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“…To aid in the comparison of the edge positions, the spectra have been normalized so that the C jump is similar between 295 eV and 300 eV. The spectrum at 100 K is consistent with spectra reported for gas phase CH 3 OH [23] and also methanol condensed on Si(1 1 1) [24]. The edge structure between 288 eV and 290 eV is related to the 3s/3p/3d Rydberg transitions.…”

Section: Adsorption and Reaction On Ceo 2 (1 1 1)mentioning

confidence: 59%

Adsorption and reaction of methanol on thin-film cerium oxide

2006

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“…Figure 7A and B show step corrected C K-edge NEXAFS spectra recorded at 123 K for 0.3 ML allyl alcohol before and after co-adsorption of hydrogen, for grazing and near normal photon incidence angles. The resonance at 282.9 eV may be assigned to the C=C bond of allyl alcohol 15,20 and evaluation of tilt angles as before 21 leads to the optimal fits shown in Figure 7C. It is apparent that in the absence of H(a) the C=C bond is quite strongly tilted with respect to the surface (~30°) consistent with bonding to the surface via the alcohol function, in agreement with the TPD data of Solomon et al 22 In marked contrast with this, the presence of H(a) markedly decreases the tilt angle to ~3°, bringing the C=C bond nearly parallel to the surface.…”

Section: Secondary Chemistry: Further Hydrogenation Of Allyl Alcohol mentioning

confidence: 99%

Chemoselective Catalytic Hydrogenation of Acrolein on Ag(111): Effect of Molecular Orientation on Reaction Selectivity

et al. 2009

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The adsorption and hydrogenation of acrolein on the Ag(111) surface has been investigated by high resolution synchrotron XPS, NEXAFS, and temperature programmed reaction. The molecule adsorbs intact at all coverages and its adsorption geometry is critically important in determining chemoselectivity toward the formation of allyl alcohol, the desired but thermodynamically disfavored product. In the absence of hydrogen adatoms (H(a)), acrolein lies almost parallel to the metal surface; high coverages force the CdC bond to tilt markedly, likely rendering it less vulnerable toward reaction with hydrogen adatoms. Reaction with coadsorbed H(a) yields allyl alcohol, propionaldehyde, and propanol, consistent with the behavior of practical dispersed Ag catalysts operated at atmospheric pressure: formation of all three hydrogenation products is surface reaction rate limited. Overall chemoselectivity is strongly influenced by secondary reactions of allyl alcohol. At low H(a) coverages, the CdC bond in the newly formed allyl alcohol molecule is strongly tilted with respect to the surface, rendering it immune to attack by H(a) and leading to desorption of the unsaturated alcohol. In contrast with this, at high H(a) coverages, the CdC bond in allyl alcohol lies almost parallel to the surface, undergoes hydrogenation by H(a), and the saturated alcohol (propanol) desorbs.

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NEXAFS studies of complex alcohols and carboxylic acids on the Si(111)(7×7) surface

Cited by 122 publications

References 29 publications

Methanol Adsorption on V2O3(0001)

Methanol Adsorption on V2O3(0001)

Adsorption and reaction of methanol on thin-film cerium oxide

Chemoselective Catalytic Hydrogenation of Acrolein on Ag(111): Effect of Molecular Orientation on Reaction Selectivity

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