Chemical Analysis of PtxNi1-x alloy single crystal surfaces by scanning tunneling microscopy

A. Biedermann, M. Schmid, and P. Varga

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

Fresenius J. Anal. Chem. 349 (1994) 201-203

Two STM investigations are presented, in which irregular tip conditions enable direct access to chemical and structural information of the surface on an atomic scale, otherwise invisible for the STM. They allow a study of surface ordering of a Pt25Ni75(111) crystal by a chemical contrast between the alloy components, and a study of carbon superstructures on a Pt10Ni90(100) surface by simultaneous imaging of substrate lattice and carbon atoms. All these images were obtained at very low tunneling resistances and thus at small tip-sample distances. A chemical interaction between the probably adsorbate covered tip and the sample is proposed to explain these images.

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

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