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Abstract. The fcc(ll0) surfaces are well known for their strong tendency to missing-row (MR) type reconstructions either in the clean state (Au, Pt) or driven by adsorbates (Ni, Cu, Pd, Ag). The present knowledge on the different reconstruction behaviour of flat (110) surfaces is reviewed. The survey focuses on recent scanning tunneling microscopy (STM) studies, which for the first time also elucidate the dynamics of the reconstruction process for the various systems. An overview of our recent STM and low energy electron diffraction studies on vicinal Au(ll0) and Ni(110) surfaces is given, aiming for a deeper understanding of the influence of steps on reconstruction behaviour of fcc(110) surfaces on the one hand, and on the stability of reconstructing vicinal surfaces on the other. Finally, we report on the reconstruction behaviour of Ir(110), which stabilizes in the clean state by formation of mesoscopic (331) facets and dereconstructs to the (1 x 1) phase upon oxygen adsorption at 700-900 K.

Scanning tunneling microscopy and LEED reveal that on regularly stepped Ni(771) the oxygen-driven missing-row reconstruction of the (110) terraces proceeds in a very transparent manner: Substrate atoms can move to adjacent terraces without crossing steps, where they line up with remaining atom rows to form linear O-Ni chains. On the resulting double-width terraces perfect missing-row structures all over the surface are formed in contrast to flat Ni(l 10); to surmount the double-step barrier, elevated temperatures (> 250°C) a**e required.

A novel design of a scanning tunneling microscope (STM) for surface science studies is described. The STM is fully compatible with ultrahigh vacuum (UHV) and offers the possibility of performing individual STM scans over a large region of the sample surface (≂10 mm2). The sample coarse approach is realized by a fine pitch screw, which shifts two wedges against each other. In order to incorporate the STM in an UHV system for the standard preparation and analyzing techniques of surface science, a special sample holder and sample transfer system has been developed. For defined heating of the sample, disconnectable electrical wiring for both a resistively heated oven and a thermocouple has been integrated within the sample holder.

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