IRAS study of π-bonded ethylene on a Pt(111) surface in the presence of gaseous ethylene and hydrogen

Adsorption of ethylene on Pt(111) in the presence of gaseous ethylene up to 1300 Pa was investigated using infrared reflection absorption spectroscopy (IRAS). Ethylene was reversibly adsorbed on bare Pt(111) at 1300 Pa and 150–180 K giving an IRAS peak at 954 cm−1 which was assigned to the out-of-plane bending mode of CH of the π-bonded ethylene. Adsorption of ethylene on Pt(111) covered by ethylidyne was next examined. It was found that ethylene was adsorbed on ethylidyne-covered Pt(111) in the presence of gaseous ethylene at 1300 Pa and 150 K but the adsorption was weaker than that on bare Pt(111). Adsorption of ethylene on bare Pt(111) from the mixture of ethylene and hydrogen (View the MathML source, v/v) was also investigated. In the presence of hydrogen gas, the adsorption of the π-bonded ethylene was also slightly inhibited.