Adsorption, Desorption, and Clustering H20 on Pt (111)
The adsorption, desorption, and clustering behavior of H20 on Pt(111) has been investigated by specular He scattering. The data show that water adsorbed on a clean Pt(111) surface undergoes a transition from a random to a clustered structure near 60 K. The initial helium scattering cross sections as a function of temperature are found to be insensitive to H20 flux over a range of 0.005 ML/s to 0.55 ML/s indicating the clustering process is more complex than simple surface diffusion. The coarsening process of an initially random distribution of water deposited at 25 K is found to occur over a broad temperature range, 60 K< T <140 K, during thermal annealing. The desorption kinetics for submonolayer water are determined to be zero-order for surface coverages greater than 0.05 ML and temperatures between 150 K and 174 K. The zero-order desorption kinetics are consistent with a two-dimensional two-phase coexistence between H2O condensed phase and a 2-gas phase on the Pt surface
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 15007026
- Report Number(s):
- PNNL-SA-39389; JCPSA6; 6500; KC0301020; TRN: US200414%%167
- Journal Information:
- Journal of Chemical Physics, 120(3):1516-1523, Vol. 120, Issue 3; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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