Determination of Adsorbate Geometries from Intramolecular Scattering in Deep-Core-Level X-Ray Photoemission: CO on Ni(001)

Abstract
In angle-resolved x-ray photoemission from the C 1s level of CO adsorbed on Ni(001), a peak in intensity with magnitude ImaxIback1.5 and full width at half maximum ≈ 25° is found to point along the surface normal. Single-scattering calculations for both a single CO molecule and a finite cluster verify that this peak is due to intramolecular scattering by O. The average orientation of CO is thus determined to be within 12° of normal, with an undetermined rms vibrational notion of ≲ 35°.