(10x2) strained reconstruction induced by oxygen adsorption on the Rh(110) surface

Oxygen adsorption on the (1x2) missing row reconstructed Rh(110) surface has been studied by means of low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), and scanning tunneling microscopy (STM). Starting from the already known (2x2)p2mg oxygen overlayer in which the substrate is (1x2) reconstructed, further oxygen has been dosed at room and lower temperatures. Upon heating, additional substrate reconstruction takes place and the surface forms a new structure with (10x2) periodicity and high local oxygen coverage. Oxygen 1s XPS measurements show a binding energy shift from 530.25 eV in the (2x2)p2mg to 529.75 eV in the (10x2) layer. Analysis of STM images reveals that in the (10x2) layer, the rhodium close-packed rows are strained and segmented in the [1 (1) over bar0] direction. On the basis of the experimental results, models for the (10x2) structure and its formation process are proposed and compared with "pseudo-oxide" structures.