1997 Volume 18 Issue 7 Pages 441-446
Adsorption of ethylene on bare and ethylidyne-covered Pt(111) surfaces in the presence of gaseous ethylene was investigated using infrared reflection absorption spectroscopy (IRAS). An IRAS peak at 954 cm-1 from ethylene was reversibly adsorbed on the bare Pt(111) at 10 Ton and 150∼180 K which was assigned to the C-H out-of-plane bending mode of n bonded ethylene. The heat of adsorption of π-bonded ethylene on Pt(111) was estimated to be 35±10 kJ/mol from the analysis of the adsorption isobar. On the ethylidyne-covered Pt(111), reversibly adsorbed π-bonded ethylene was also observed under the same condition where an IRAS peak at 954 cm-1 appeared. The adsorption of π-bonded ethylene on ethylidyne-covered Pt(111) was weaker than that on the bare Pt(111).