Real-space observation of the 2×1 structure of chemisorbed oxygen on Ni(110) by scanning tunneling microscopy

We present the first real-space observation of well defined single adsorbates: Oxygen atoms forming the 2×1 structure on Ni(110). The sawtooth model is consistent with all experimental results. The structure consists of domains, separated in the [11»0] direction by uncovered Ni ribbons 1 surface unit cells wide. Such domain walls appear responsible for the =0.35 coverage of the saturated chemisorption structure. © 1984 The American Physical Society.