A Surface Core Level Shift Study of Hydrogen-Induced Ordered Structures on Rh(110)

The interaction of hydrogen with Rh(110) was studied by means of high-resolution core level photoelectron spectroscopy, in combination with temperature-programmed desorption spectroscopy, low energy electron diffraction, and scanning tunneling microscopy measurements. By exploiting the H-induced Rh3d 5/2 surface core level shift sensitivity to the local coordination environment, we propose here new structural models for the intermediate coverage 0.67 and 1.0 ML overlayers, while we confirm the previous results for the low coverage structures at 0.33 and 0.5 ML, and for the saturation phase at 2.0 ML. Surface core level shift values are interpreted on the basis of our previous data about the hydrogen adsorption on the (100) and (111) rhodium surfaces. The proposed structural models are supported by scanning tunneling images of the surface and provide a comprehensive description of all the available experimental data.