PHYS 326 |
| With single molecule spectroscopy we probe the dynamics of local environments in glasses, which is characterized by a spatially heterogeneous rate of rearrangement within a local environment, the relaxation rate, and the rate of exchange between environments, the lifetimes of these heterogeneities. With different probe molecules in polyvinyl acetate, we determine both rates close to the glass transition temperature using correlation analysis. The temperature dependence of the relaxation times agrees well with dielectric experiments from the literature, the absolute time scales from our single molecule experiments are slower by a constant factor that depends on the size of the probe molecule: from 80-fold for Rhodamine B to about 5-fold for the smaller iodine. The ratio of observed single molecule reorientation times to heterogeneity lifetimes is close to one for both probe molecules at all investigated temperatures. |
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PHYS Poster Session - Optical Probes of Dynamics in Complex Environments
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Division of Physical Chemistry |