(submitted to J. Chem. Phys.)
G. A. Kimmel(1), B. D. Kay(1), and M. Persson(2)
(1)Pacific Northwest National Laboratory, Environmental Molecular Sciences Laboratory,
902 Battelle Blvd. P.O. Box 999, MSN K8-88, Richland, WA 993552
(2)Department of Applied Physics, Chalmers/Göteborg
University, S-412 96 Göteborg, Sweden
The influence of adlayer compression on the physisorptio of Ar on Pt(111) is investigated using temperature programmed desorption and modulated beams. We find that the difference in coverage between the compressed and uncompressed first layer is ~10-15 %. For coverages near oe monolayer, this compression causes nearly temperature independent desorption kinetics over a wide temperature range (32K - 41K). We present a theroy taht includes the effect of the compression on the desorption kinetics and explains the observed kinetics in terms of a competition between adsorbate-substrate and adsorbate-adsorbate interactions resulting in a continuous increass in the chemical potential near the completion of each succesive layer.