Medium energy ion scattering studies of clean and CO covered Ni(110)

The technique of medium energy ion scattering, using channeling and blocking, has been used to study the geometric structure of clean and adsorbate covered Ni(110). The experimental setup includes a specially constructed 180 keV ion accelerator and a UHV scattering chamber, equipped with a three axis goniometer and a solid state detector for energy analysis of the scattered beam. The results for clean Ni(110) show that the spacing between the two outermost layers is contracted by 4±1%, in excellent agreement with earlier high resolution studies. When CO is adsorbed in a configuration [a (2×1)p1g1 LEED pattern] with one CO atom for each Ni surface atom, the surface returns to the normal bulk configuration.