| AVS 55th International Symposium & Exhibition | |
| Surface Science | Friday Sessions |
| Session SS+AS+NC-FrM |
| Session: | Environmental Surfaces and Water Interaction with Oxide Surfaces |
| Presenter: | J. Matthiesen, Pacific Northwest National Laboratory |
| Authors: | J. Matthiesen, Pacific Northwest National Laboratory R.S. Smith, Pacific Northwest National Laboratory B.D. Kay, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
Molecular beams, temperature programmed desorption, and infrared spectroscopy were used to study the diffusive intermixing of amorphous water and methanol nanoscale films. Composite films with initially separated layers were created by sequential dosing at 25 K in UHV. The films were then heated and the extent of intermixing was determined by the onset of desorption of the underlayer species and changes in the infrared spectra. Both linear ramp and isothermal experiments were conducted. In a series of experiments the layer thickness, film composition, and heating rate were varied to extract quantitative temperature dependent diffusivities. Isotopically labeled methanol was used to mimic tracer-type experiments. These results compare favorably to the results obtained from separated layer experiments. Numerical simulations of the diffusive intermixing were used to quantitatively model the experimental results. 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.