Intramolecular and multiple scattering in SEXAFS of an adsorbed small molecule

Abstract

Using a multiple scattering ‘curved wave’ computational scheme we show that published O K-edge EXAFS spectra of gas phase CO2 and CO can be simulated and used to optimise O and C scattering phase shifts. With these parameters fixed we show that published O K-edge SEXAFS from adsorbed formate (HCOO) on Cu(110) can be reconciled with the adsorbate-substrate registry determined for this system by photoelectron diffraction, and in particular that the normal incidence spectrum is totally dominated by intramolecular scattering, with the largest contribution arising from C backscattering, but with backscattering and multiple scattering also playing a role. The calculations indicate some sensitivity, over the 140 eV data range available, to the internal conformation of the molecule.