IR-visible sum-frequency generation(SFG) spectroscopy has been used in a total internal reflection geometry to study the molecular structure of polystyrene (PS) at PS/sapphire and PS/air interfaces, simultaneously. The symmetric vibrational modes of the phenyl rings dominate the SFG spectra at the PS/air interface as compared to the antisymmetric vibrational modes at the PS/sapphire interface. This indicates approximately parallel orientation of the phenyl rings at the PS/air interface while nearly perpendicular orientation at the PS/sapphire interface, with respect to the surface normal.
Physical Review Letters
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Copyright 2000 American Physical Society. The original published version of this article may be found at http://dx.doi.org/10.1103/PhysRevLett.85.3854.
Gautam, K. S.; Schwab, Alexander D.; Dhinojwala, Ali; Zhang, D.; Dougal, S. M.; and Yeganeh, M. S., "Molecular Structure of Polystyrene at Air/Polymer and Solid/Polymer Interfaces" (2000). College of Polymer Science and Polymer Engineering. 24.