Multiple-scattering analysis of the structure of ethylene adsorbed on the Cu(100) surface

Abstract
The carbon K-shell near-edge x-ray-absorption fine-structure (NEXAFS) spectra of gas-phase ethylene molecules and ethylene adsorbed on the Cu(100) surface have been calculated by the multiple-scattering cluster method. The calculated result shows the existence of the C-H scattering resonance in carbon K-shell NEXAFS spectra of the adsorbed ethylene molecules. By a comparison between the theoretical results and the experimental spectra, we have found that the C-C bond midpoint occupies a fourfold hollow site 1.3 Å above the Cu surface with the C-C axis being parallel to the [001] or [010] direction. The bond lengths of C-C and Cu-C are equal to 1.46±0.04 and 1.90±0.03 Å, respectively, and the H-C-H bond angle equals 130±5°. These results are in agreement with those of Fourier-transform analysis of the surface extended x-ray-absorption fine structure.