Sum Frequency Generation Studies of Surfaces of High-Surface-Area Powdered Materials

We report the first observation of sum frequency generation (SFG) photons on high-surface-area powders, critically important materials in heterogeneous catalysis. We utilize SFG in total internal reflection (TIR) geometry and show that the TIR−SFG approach markedly reduces the destructive interferen...

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Bibliographic Details
Published in:Langmuir 2006-01, Vol.22 (2), p.637-641
Main Authors: Yeganeh, Mohsen S, Dougal, Shawn M, Silbernagel, Bernard G
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
General and physical chemistry
Surface physical chemistry
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Summary:We report the first observation of sum frequency generation (SFG) photons on high-surface-area powders, critically important materials in heterogeneous catalysis. We utilize SFG in total internal reflection (TIR) geometry and show that the TIR−SFG approach markedly reduces the destructive interference associated with nonlinear optical spectroscopy of small particle surfaces, making SFG studies of high-surface-area powders possible. The index of refraction of materials and their distance from the TIR−SFG prism are key parameters in generating and detecting the sum frequency signal. We find that TIR−SFG is highly sensitive to capillary condensation. To demonstrate the capability of the TIR−SFG technique, we measure the thermodynamics of methanol adsorption and desorption on high-surface-area SiO2.
ISSN:0743-7463
1520-5827
DOI:10.1021/la0518905