Local bonding geometry of O(2×1) on Ni(110): A surface extended x-ray-absorption fine-structure study

Abstract

Oxygen K-edge surface extended x-ray-absorption fine-structure spectra measured with significantly improved signal-to-noise ratio reveal novel features of the intriguing (2\times\else\texttimes\fi{}1) oxygen-induced reconstruction of Ni(110). The spectrum obtained for E parallel to [001] unambiguously indicates that each oxygen sits in a long-bridge position 0.56 A\r{} away from the nearest topmost Ni row. The relatively short Ni-O distance inferred from data obtained with E parallel to [1\bar\else\textasciimacron\fi{}10] can only be explained if each oxygen is tilted towards (100) facets of the reconstructed substrate. The amplitude ratio ${A}^{1\bar\else\textasciimacron\fi{}10}$/${A}^{001}$ favors the sawtooth model over the missing-row model.