The formation of ethylidyne on the Rh(100) single crystal surface by the coadsorption of ethylene and carbon monoxide

Abstract

We report high-resolution electron energy loss (HREEL) spectra which we believe demonstrate that ethylidyne species (CCH 3) can be formed on a Rh(100) surface. While we cannot determine the surface binding site, this is the first time ethylidyne has been identified on a surface which lacks three-fold hollow sites. The monolayers were formed by preadsorbing a partial monolayer of carbon monoxide (θ CO = 0.5) followed by room temperature adsorption of ethylene to generate the ethylidyne species. Adsorption of ethylene alone produces a mixture of hydrocarbon fragments which includes ethylidyne, but whose HREEL spectrum is complex and difficult to assign. These ethylidyne species are thermally stable up to 350 K. Based on the HREEL spectra, the ethylidyne stands approximately upright on the surface with its carbon-carbon bond along the surface normal.