AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP29
Rebound Transitions in Surface Diffusion

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: G. Antczak, University of Illinois
Correspondent: Click to Email

We have examined in detail the mechanism of surface diffusion on an atomic scale for the W(211) plane. Types of movement as well as their kinetics have been identified. The investigations are based on the distribution of displacements of single atoms on planes around 15 spaces in diameter. The distribution for any one temperature consists of at least 1200 observations. Special attention was paid to transient temperature effects during cooling and warming of the sample. At a temperature 1/10 the melting point we identified, in addition to standard single jumps in the <111> direction, double jumps along <111> as well as rebound jumps which occur when an atom starts in the <111> direction but turns back and lands at the starting point. In the investigated temperature range we have not observed any triple jumps. The kinetics of all kinds of jumps were derived, and the correlation between different types of jumps was investigated. We found that double as well rebound jumps originate from single jumps. The increasing significance of non-nearest-neighbor transitions gradually diminishes the rate of single transitions, which almost reaches zero at 320 K. Rebound jumps start to be noticeable at 300K and seem to be quite frequent in diffusion over the W(211) plane. Surprisingly, their energy is lower then the activation energy for double transitions, 1.03 eV compared with 1.44 eV for double jumps. The reason for that is not completely clear, but possible factors involved will be presented. Research supported by the Department of Energy under Grant No. DEFG02-91ER45439 to the Materials Research Lab.