Effect of surface structure on catalytic reactions: A sum frequency generation surface vibrational spectroscopy study

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In the results discussed above, it is clear that Sum Frequency Generation (SFG) is a unique tool that allows the detection of vibrational spectra of adsorbed molecules present on single crystal surfaces under catalytic reaction conditions. Not only is it possible to detect active surface intermediates, it is also possible to detect spectator species which are not responsible for the measured turnover rates. By correlating high-pressure SFG spectra under reaction conditions and gas chromatography (GC) kinetic data, it is possible to determine which species are important under reaction intermediates. Because of the flexibility of this technique for studying surface intermediates, ... continued below

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180 pages

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McCrea, Keith R. September 7, 2001.

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In the results discussed above, it is clear that Sum Frequency Generation (SFG) is a unique tool that allows the detection of vibrational spectra of adsorbed molecules present on single crystal surfaces under catalytic reaction conditions. Not only is it possible to detect active surface intermediates, it is also possible to detect spectator species which are not responsible for the measured turnover rates. By correlating high-pressure SFG spectra under reaction conditions and gas chromatography (GC) kinetic data, it is possible to determine which species are important under reaction intermediates. Because of the flexibility of this technique for studying surface intermediates, it is possible to determine how the structures of single crystal surfaces affect the observed rates of catalytic reactions. As an example of a structure insensitive reaction, ethylene hydrogenation was explored on both Pt(111) and Pt(100). The rates were determined to be essentially the same. It was observed that both ethylidyne and di-{sigma} bonded ethylene were present on the surface under reaction conditions on both crystals, although in different concentrations. This result shows that these two species are not responsible for the measured turnover rate, as it would be expected that one of the two crystals would be more active than the other, since the concentration of the surface intermediate would be different on the two crystals. The most likely active intermediates are weakly adsorbed molecules such as {pi}-bonded ethylene and ethyl. These species are not easily detected because their concentration lies at the detection limit of SFG. The SFG spectra and GC data essentially show that ethylene hydrogenation is structure insensitive for Pt(111) and Pt(100). SFG has proven to be a unique and excellent technique for studying adsorbed species on single crystal surfaces under high-pressure catalytic reactions. Coupled with kinetic data obtained from gas chromatography measurements, it can give much insight into how the structure of a single crystal surface affects the chemistry of a catalytic reaction by detecting surface species under reaction conditions.

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180 pages

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OSTI as DE00789179

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  • Other Information: TH: Thesis (Ph.D.); Submitted to University of California, Berkeley, CA (US)

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  • Report No.: LBNL--48961
  • Grant Number: AC03-76SF00098
  • Office of Scientific & Technical Information Report Number: 789179
  • Archival Resource Key: ark:/67531/metadc722760

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • September 7, 2001

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  • Sept. 29, 2015, 5:31 a.m.

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  • April 4, 2016, 4:06 p.m.

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McCrea, Keith R. Effect of surface structure on catalytic reactions: A sum frequency generation surface vibrational spectroscopy study, thesis or dissertation, September 7, 2001; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc722760/: accessed October 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.