AVS 50th International Symposium
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA8
Electron-stimulated Reactions in Thin Amorphous Solid Water Films on Pt(111).

Monday, November 3, 2003, 4:20 pm, Room 326

Session: Stimulated Processes at Surfaces
Presenter: G.A. Kimmel, Pacific Northwest National Laboratory
Authors: G.A. Kimmel, Pacific Northwest National Laboratory
N.G. Petrik, Pacific Northwest National Laboratory
Correspondent: Click to Email
The electron-stimulated production of D@sub 2@ from amorphous solid D@sub 2@O deposited on Pt(111) is investigated as a function of film thickness. The D@sub 2@ yield has two components with distinct reaction kinetics. Using isotopically layered films of H@sub 2@O and D@sub 2@O demonstrates that the D@sub 2@ is produced in reactions that occur at both the Pt/amorphous solid water (ASW) interface and the ASW/vacuum interface, but not in the bulk. The energy for the reactions, however, is absorbed in the bulk of the films and electronic excitations migrate to the interfaces where they drive the reactions. At the Pt(111) surface, the electronic excitations cause dissociation of water molecules at the interface, leading to the build-up of adsorbed hydrogen atoms. A model based on the diffusion of electronic excitations to either interface accounts for the principle experimental observations.