Vibrational sum frequency spectroscopy of surfactants and phospholipid monolayers at liquid-liquid interfaces

Beth L. Smiley; R. A. Walker; D. E. Gragson; T. E. Hannon; Geraldine L. Richmond

doi:10.1117/12.306122

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24 April 1998 Vibrational sum frequency spectroscopy of surfactants and phospholipid monolayers at liquid-liquid interfaces

Beth L. Smiley, R. A. Walker, D. E. Gragson, T. E. Hannon, Geraldine L. Richmond

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Proceedings Volume 3273, Laser Techniques for Condensed-Phase and Biological Systems; (1998) https://doi.org/10.1117/12.306122
Event: Optoelectronics and High-Power Lasers and Applications, 1998, San Jose, CA, United States

Abstract

Work from our laboratory on vibrational sum frequency spectroscopic investigations of molecular ordering at the carbon tetrachloride-water interface is reviewed. Simple charged surfactants adsorbed at the liquid-liquid interface are seen to induce alignment of interfacial water molecules to a degree which is dependent on the induced surface potential. Saturation of water molecule alignment occurs at a surfactant surface concentration corresponding to a calculated surface potential of approximately 160 mV. In complementary studies, the relative degree of hydrocarbon chain ordering within monolayers of symmetric phosphatidylcholines of different chain lengths is inferred by the relative signal contributions of the methyl and methylene symmetric stretch modes. The degree of hydrocarbon chain disorder observed depends strongly on the method of monolayer preparation. By one method, a decrease in hydrocarbon chain order is seen with increasing chain length. Another method of monolayer formation yielded very well ordered hydrocarbon chains for the longest chain phosphatidylcholine studied, and showed much greater disorder in shorter chain species which was comparable to the other preparation method. These studies are a foundation for further work with this technique geared towards understanding molecular-level structural features in membrane-like assemblies and surface biochemical interactions of relevance to biomedical research.

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Beth L. Smiley, R. A. Walker, D. E. Gragson, T. E. Hannon, and Geraldine L. Richmond "Vibrational sum frequency spectroscopy of surfactants and phospholipid monolayers at liquid-liquid interfaces", Proc. SPIE 3273, Laser Techniques for Condensed-Phase and Biological Systems, (24 April 1998); https://doi.org/10.1117/12.306122

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