Photoelectron diffraction study of O, N and C adsorption structures on Ni(100) and Cu(110)

Scanned energy mode adsorbate 1s photoelectron diffraction measurements have been taken from half-monolayer structures of O on Ni(100) and on Cu(110), and from C and N on Ni(100). The sensitivity of these data to the various structural parameters of these surface phases is investigated. In particular, the fact that 180° scattering contributions typically dominate the spectra in this form of the photoelectron diffraction experiment leads to a strong sensitivity to adsorbate–second layer substrate spacings. Even in the case in which the adsorbate and top substrate layers are nearly coplanar, however, some sensitivity to top layer geometry is retained, except in the case of the Cu(110) surface for which the lower rotational symmetry, combined with the plane polarisation of the incident radiation, leads to insensitivity to certain sites.