COLL 353 |
| Jeff Turner1, Ashis Mukhopadhyay2, Sung Chul Bae2, Sangmin Jeon2, and Steve Granick3. (1) Department of Chemistry, University of Illinois, 104 S Goodwin, Urbana, IL 61801, (2) Department of Materials Science and Engineering, University of Illinois, 104 S Goodwin, Urbana, IL 61801, (3) 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 |
| When a fluid is confined to a film only a few molecules thick, its structure and properties deviate significantly from the bulk. Over the past few decades, force measurements on these systems were the primary experiments probing these deviations. Recently, our laboratory has developed experimental platforms by which we combine optical (time-resolved fluorescence) measurements with classical force measurements. By exciting dye molecules in a series of polar and nonpolar liquids with two polarized photons and monitoring the polarization of the emission as a function of time (8 ps resolution, 12 ns window), we measure the dye’s rotational diffusion coefficient, (Tau)rot. As the system is confined, viscosity increases resulting in slower rotation of the probe. Multiple rotational diffusion coefficients appear upon confinement, suggesting heterogeneity in the sample. These rotational diffusion measurements are compared to previous measurements of translational diffusion performed in our laboratory. |
|
Friction, Lubrication, and Adhesion in Micro- and Nano-Scale Devices
2:00 PM-5:10 PM, Tuesday, March 30, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |