Chemically diverse environmental interfaces and their reactions with ozone studied by sum frequency generation

Stokes, Grace Y.; Buchbinder, Avram M.; Gibbs, Julianne M.; Scheidt, Karl A.; Geiger, Franz M.

doi:10.1016/j.vibspec.2008.08.003

Cited by 39 publications

(103 citation statements)

References 123 publications

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“…We have observed this effect previously in a terminal alkene bound covalently to a silica substrate through its other end. 81,83 The presence of these two features and no others is consistent with an orientation in which the long axis of the molecule lies parallel to the surface, much like the n-alkanes discussed above.…”

Section: Acyclic Olefinssupporting

confidence: 68%

“…More details regarding the fitting procedure can be found in the Supporting Information and in earlier work. 83,84,136 Absolute intensities are not directly comparable between SSP and SPS spectra in our setup because S-and P-polarized light of the same intensities will not reach the sample surface with the same efficiencies due to the use of a flat window in an internal reflection geometry. 145 SFG measurements were made at the (0001) surface of a single crystalline R-alumina window (ISP optics) in internal reflection geometry (Scheme 1).…”

Section: Sum Frequency Generationmentioning

confidence: 99%

“…83,122,136 The development of this technique 137-139 and the theoretical basis for SFG at interfaces [140][141][142][143][144][145] is detailed elsewhere. A brief description of our setup follows.…”

Section: Sum Frequency Generationmentioning

confidence: 99%

“…This spectrum should be compared to our previous work in which a strong signal was observed at 3035 cm -1 in the SSP polarized SFG spectrum for a cyclohexene moiety covalently linked to glass through a silane linkage, which we assigned to a C-H stretching mode of the olefin carbons. 81,83 The extremely low strength of this mode for physisorbed cyclohexene at the vapor/solid interface may indicate that the plane of the olefin substituents lies parallel to the interface.…”

Section: Cyclopentanementioning

confidence: 99%

“…Although much work has been carried out on understanding reactivity and kinetics on metal substrates relevant to catalysis, [43][44][45][46][47][48][49][50][51][52][53][54][55] vibrational studies focusing on the interaction of catalytically relevant oxides [56][57][58][59][60][61][62] with hydrocarbons are more sparse [63][64][65][66][67][68][69] and tend not to focus on determining the molecular orientations of the hydrocarbon species at the catalytically relevant surface unless they are computational. 70,71 Bridging this knowledge gap could improve many research fields, including catalyst performance and design, [72][73][74][75][76][77][78] chromatographic separations, 79,80 environmental chemistry, [81][82][83][84][85][86][87][88][89] and tribology. [90][91][92] B...…”

Section: Introductionmentioning

confidence: 99%

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Pentane, Hexane, Cyclopentane, Cyclohexane, 1-Hexene, 1-Pentene,cis-2-Pentene, Cyclohexene, and Cyclopentene at Vapor/α-Alumina and Liquid/α-Alumina Interfaces Studied by Broadband Sum Frequency Generation

2009

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The molecular orientation and structure of adsorbates at oxide interfaces is driven by surface-molecule and molecule-molecule interactions and is useful for predicting reactivity and product selectivity in heterogeneous chemical reactions, including those important in catalytic processes. Using broadband vibrational sum-frequency generation spectroscopy, we probed cyclic and acyclic alkanes and olefins at buried vapor/solid and liquid/ solid interfaces of the R-alumina (0001) surface under ambient conditions. The spectroscopic signatures of the adsorbates were measured and compared with bulk phase spectra and spectra of model surfaces containing hydrocarbons covalently linked to glass slides using silane chemistry. By utilizing appropriate polarization combinations, the orientations of hydrocarbons adsorbed from the vapor were evaluated and compared to the hydrocarbon orientations at the liquid/solid interface. The data support a proposed orientation for n-alkanes and cycloalkanes at the liquid/solid interface in which the hydrocarbons lie with the planes of their carbon backbones parallel to the surface, whereas at the vapor/solid interface, the adsorbates are oriented with their carbon backbones in an orientation neither parallel nor perpendicular to the surface. The surface vibrational spectra of olefins at both types of interfaces indicate that their orientations differ from saturated counterparts, and their unique spectral signatures allow differentiation of adsorbed olefins from alkanes.

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Section: Acyclic Olefinssupporting

confidence: 68%