| AVS 56th International Symposium & Exhibition | |
| Surface Science | Thursday Sessions |
| Session SS-ThP |
| Session: | Surface Science Poster Session |
| Presenter: | J. Matthiesen, Pacific Northwest National Laboratory |
| Authors: | J. Matthiesen, Pacific Northwest National Laboratory R.S. Smith, Pacific Northwest National Laboratory B. Kay, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
Molecular beams, temperature programmed desorption, and infrared spectroscopy were used to study the diffusivity in nanoscale supercooled liquid films of alkanes and alcohols. Amorphous films were grown on top of a layer of rare-gas atoms on a Pt(111) substrate at 25 K in UHV. As the films are heated they transform from amorphous to supercooled liquid films around the glass transition temperature. The rare-gas atoms were found to diffuse through the films in the supercooled liquid state. In a series of experiments, the layer thickness and heating rate were varied to extract diffusivities over a range of different temperatures. Numerical simulations of the rare-gas atoms diffusing through the supercooled films were used to quantitatively model the experimental results. Mixing of initially layered isotopically labeled alcohol and alkane films were also performed. The extracted diffusivities for the rare-gas atoms were in good agreement with the self-diffusion coefficients extracted from the experiments with isotopically labeled species. The details of the experiment and the interpretation of the results will be discussed in detail.
The research described here was performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.