Plan-view imaging of oxygen-induced reconstruction on Ag(110) surface. I. The possibility of imaging surface oxygen

Surface reconstruction on Ag(110) induced by oxygen adsorption was studied by the plan-view imaging technique of high-resolution electron microscopy (HREM). Systematic multislice simulations were carried out to find the optimal experimental conditions for imaging the surface oxygen. It was found theoretically that there exist a series of characteristic values of objective lens defoci and sample thicknesses under which the surface and the bulk can be imaged clearly and simultaneously. These optimal imaging conditions were used to interpret the experimental micrographs. While the basic features of the surface reconstruction of O/Ag(110) in the HREM images are consistent with those revealed by scanning tunnelling microscopy (STM), there are some new features that have not been reported with STM. These phenomena give some evidence to the existence of subsurface oxygen.