GEOC 84 |
| Adelé Poynor, Departments of Physics, University of Illinois, 104 S Goodwin, Urbana, IL 61801, Ashis Mukhophadyay, Departments of Materials Science and Engineering, University of Illinois, 104 S Goodwin, Urbana, IL 61801, and Steve Granick, Departments of Materials Science and Engineering, of Chemistry, of Physics, and of Chemical and Biomolecular Engineering, University of Illinois, 104 S Goodwin, Urbana, IL 61801. |
| Although understanding hydrophobic interfaces is important for a wide variety of fields (from protein folding to designing stain resistant clothing), the details are still disputed. We have made in-situ measurements of octadecyltriethoxysiloxane and octadecanethiol surfaces submerged in water with an ultra-sensitive time-resolved phase-modulated ellipsometer. We have observed evidence for a low refractive index layer at the interface. This “vapor” layer has surprisingly large fluctuations even with the spatial (over a beam size of 1mm) and temporal (with a time constant of 30 ms) averaging inherent in the measurement. The power spectrum shows intriguing power law dependence. Studies on the temperature dependence indicate that the vapor layer becomes thicker as the temperature increases. |
|
Interfacial Phenomena: Linking Atomistic and Macroscopic Properties
1:00 PM-5:50 PM, Tuesday, March 30, 2004 Marriott -- Marquis NW, Oral
Division of Geochemistry |