Chemically resolved STM on a PtRh(100) surface

P. T. Wouda*, B. E. Nieuwenhuys*, M. Schmid, and P. Varga

*Department of Heterogeneous Catalysis and Surface Science, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands

Institut für Allgemeine Physik, Technische Universität Wien, A-1040 Wien, Austria

Surf. Sci. 359 (1996) 17-22

Scanning Tunneling Microscopy on PtRh(100) (molar bulk composition 1:1) has revealed the possibility of direct determination of the surface structure of this system. During measurements at low tunneling resistance (<500 K Ohm), the Pt and Rh atoms appear with a clearly observable height difference of more than 20 pm. No long range ordering has been found. Variation of the sample preparation method and comparison of STM and Auger Electron Spectroscopy measurements led to the conclusions that there is a preferential surface segregation of platinum, that rhodium atoms are the ones with the highest apparent height, and that there is a limited tendency of clustering on the surface. Furthermore, it was found that platinum atoms preferentially populate the step edges on this crystal surface.

Corresponding author: M. Schmid (schmid< encoded email address >).

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Part of this work is on display in the IAP/TU Wien STM Gallery (see the chemical resolution page).