Molecularly adsorbed CO on Pd(110) was found to cause substantial reconstruction of the surface at coverages ranging from 0.3 to 0.75. Within this range, the adsorbate-covered reconstructed surface exhibited a 4 x 2 low-energy electron diffraction pattern. However, the exact nature of the reconstruction was unclear. Low-energy electron diffraction analysis of the CO/Pd(110)-type 4 x 2 structure was carried out in order to establish the type of reconstruction which was induced at the metal surface. This showed that the low-energy electron diffraction profiles of integral order, and some half-order beams of the CO/Pd(110)-type 4 x 2 pattern, closely resembled the profiles which were predicted for a Pd(110)-type 1 x 2 missing-row structure. There was also a marked resemblance to experimental low-energy electron diffraction profiles for the Cs/Pd(110)-type 1 x 2 structure, which had been shown to exhibit the missing-row structure. On the basis of this evidence it was concluded that the CO/Pd(110)-type 4 x 2 low-energy electron diffraction pattern arose from a missing-row reconstruction of the Pd(110)-type surface. This gave rise to a strong underlying 1 x 2 pattern, plus a poorly ordered CO overlayer which produced weak diffuse fourth-order spots in the low-energy electron diffraction pattern.

P.Hu, L.Morales de la Garza, R.Raval, D.A.King: Surface Science, 1991, 249[1-3], 1-7