AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS3-ThA

Paper SS3-ThA2
CO Diffusion on Cu(111): Effects of CO-CO Interactions

Thursday, November 18, 2004, 2:20 pm, Room 213B

Session: Surface Diffusion and Transport
Presenter: B.V. Rao, University of California, Riverside
Authors: B.V. Rao, University of California, Riverside
R. Perry, University of California, Riverside
A. Liu, University of California, Riverside
L. Bartels, University of California, Riverside
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Diffusion is the surfaces process that occurs most frequently and, thus, may arguably be regarded the most important one. With the advent of low-temperature scanning tunneling microscopy one is able to image and track the motion of individual atoms and molecules on surfaces for long periods of time@footnote 1@. We probed the diffusion of CO molecules on Cu(111) at temperatures between 17 and 50 K. At 17K, molecular hops are infrequent and occur on the time-scale of hours, whereas at 50K the hopping frequency has reached >1 Hz. Measurements at various temperatures indicate that the diffusion of isolated CO molecules follows an Arrhenius behavior. Our investigation puts special attention on the effect of neighboring CO molecules on the hopping direction and frequency. Preliminary results suggest, that the CO-CO interaction enhances or decreases CO diffusion depending on the separation of the molecules. The distance dependence resembles the oscillation patter of the Cu(111) surface state, similar to Cu adatom interactions previously reported by Repp et al.@footnote 2@. @FootnoteText@ @footnote 1@Briner, B.G., Doering, M., Rust, H.-P., Bradshaw, A. M., Science 278 (1997) 257.@footnote 2@Repp J., Moresco F., Meyer G., Rieder K.H., Hyldgaard P., Persson M., Phys. Rev. Lett., 85 (2000) 2981 .