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When scanning tunneling microscopy gets the wrong adsorption site: H on Rh(100).

Research paper by C C Klein, A A Eichler, E L D EL Hebenstreit, G G Pauer, R R Koller, A A Winkler, M M Schmid, P P Varga

Indexed on: 06 Jun '03Published on: 06 Jun '03Published in: Physical review letters



Abstract

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.