When scanning tunneling microscopy gets the wrong adsorption site: H on Rh(100).
At low tunneling resistance, scanning tunneling microscopy (STM) images of a Rh(100) surface with adsorbed hydrogen reproducibly show protrusions in all bridge sites of the surface, leading to a naive interpretation of all bridge sites being occupied with H atoms. Using quantitative low-energy electron diffraction and temperature programmed desorption we find a much lower H coverage, with most H atoms in fourfold hollow sites. Density functional theory calculations show that the STM result is due to the influence of the tip, attracting the mobile H atoms into bridge sites. This demonstrates that STM images of highly mobile adsorbates can be strongly misleading and underlines the importance of additional analysis techniques.
Klein
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Institut für Allgemeine Physik, Vienna University of Technology, A-1040 Vienna, Austria.
Eichler
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A
Hebenstreit
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EL
Pauer
G
G
Koller
R
R
Winkler
A
A
Schmid
M
M
Varga
P
P