Adsorption of chlorine on Ru(0001)—A combined density functional theory and quantitative low energy electron diffraction study

Abstract

Chlorine adsorption on Ru(0001) surface has been studied by a combined density functional theory (DFT) and quantitative low energy electron diffraction (LEED) approach. The (√3×√3)R30°-Cl phase with ΘCl=1/3ML and chlorine sitting in fcc sites has been identified by DFT calculations as the most stable chlorine adsorbate structure on Ru(0001) with an adsorption energy of −220kJ/mol. The atomic geometry of (√3×√3)R30°-Cl was determined by quantitative LEED. The achieved agreement between experimental and simulated LEED data is quantified by a Pendry factor of rP=0.19 for a fcc adsorption site with a Cl-Ru bond length of 2.52Å. At chlorine coverages beyond 1/3ML LEED reveals diffuse diffraction rings, indicating a continuous compression of the hexagonal Cl overlayer with a preferred average Cl–Cl distance of 4.7Å in the (√3×√3)R30°-Cl, ΘCl=1/3 ML phase towards 3.9Å at saturation coverage of 0.48ML.