Orientation of ethylene and propylene on Ag(110) from near edge x-ray adsorption fine structure

The π bond orientation of ethylene and propylene on the clean and atomic oxygen covered Ag(110) surfaces has been determined with near-edge x-ray absorption fine-structure (NEXAFS) measurements. The π system of ethylene is tilted 20±5° and 18±5° from the surface normal for ethylene on the clean and atomic oxygen covered surfaces, respectively. The tilt angle of the π system is 20±5° on the clean surface and 31±5° on the atomic oxygen covered surface. On both the clean and atomic oxygen covered surface, the carbon–carbon double bond in ethylene and propylene appears to form a π-donor type bond with the Ag(110) surface.