STM Morphology and Crystallography

The 0-induced reconstruction, in both the O-Rh(llO) and O-Pd(llO) surfaces, is usually assumed as the MR type. One out of a certain number of the Rh(Pd) rows is removed from the surface. Common to other oxygen-metal systems, the first-layer spacing expands and the second contracts. 

It is surprising that, as the oxygen coverage increases, the number of missing rows reduces from every other (1/2) to every nth (1/n) and, finally, to zero. It remains a puzzle how the adsorbates can turn the atomic vacancies into real atoms that are then buckled up. 

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