Dresden 2006 – scientific programme

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O: Oberflächenphysik

O 36: Structure and dynamics

O 36.1: Talk

Thursday, March 30, 2006, 11:15–11:30, WIL C207

Living on the Edge: Life and Death of Vacancies in Cu(100) — •Koen Schoots, Thomas H. Beuman, Marcel J. Rost, and Joost W.M. Frenken — Leiden Institute of Physics, Universiteit Leiden, Leiden, The Netherlands

We have used STM to investigate where surface vacancies originate and annihilate on Cu(100).

Because of the extremely high mobility of the surface vacancies, we have been forced to use tracer particles to follow the vacancy motion, in the form of In atoms, incorporated in the top layer. The No-dqslide-puzzleNo-dq- diffusion of the vacancies makes the In atoms move through the surface, as has been reported in [1,2].

In the present study, we have employed tailor-made geometries, in which the In atoms were surrounded exclusively by upward or by downward steps. Our STM movies show a striking difference between these two cases, with differences in jump frequencies and average jump lenghts of more than one order of magnitude. These results show that vacancies are primarily created at the upper side of a step and can be formulated in analogy with the energetics of ad-atoms, in terms of an Ehrlich-Schwoebel barrier [3] for surface vacancies.

[1] R. van Gastel et al., Nature 408 (2000) 665, Phys. Rev. Lett. 86 (2001) 1562, Surf. Sci 521 (2002) 10, Surf. Sci. 521 (2002) 26.

[2] M.L. Grant et al., Phys. Rev. Lett. 86 (2001) 4588.

[3] G. Ehrlich et al., J. Chem. Phys. 44 (1966) 1039.