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P. Kostelnik, T. Sikola, P. Varga, M. Schmid:
"A LEED study of NO superstructures on the Pd(111) surface";
Journal of Physics: Condensed Matter, 21 (2009), 1340051 - 1340057.

We have examined two adsorption structures of NO on the Pd(111) surface and the
transformation between them. Low-energy electron diffraction (LEED) I (V ) curves of the
Pd(111)-p(2 °- 2)-NO and Pd(111)-c(4 °- 2)-NO surface structures were acquired and analyzed
using tensor LEED. Our structural models confirm a previous study by scanning tunneling
microscopy and DFT (Hansen et al 2002 Surf. Sci. 496 1). In the c(4 °- 2)-NO structure, which
forms at an NO coverage of 0.5 monolayers (ML), the NO molecules occupy fcc and hcp
hollow sites and are almost upright with only slight tilting, possibly related to NO-NO
repulsion. In the p(2 °- 2)-NO structure (0.75 ML), with two NO molecules in hollow sites and
one in an on-top site, we find strong tilting of the on-top molecule. Upon heating, thermal
desorption of NO leads to a transition from the p(2 °- 2) to the c(4 °- 2) structure, which leads to
splitting of the diffraction spots and/or streaky spots. The transition is discussed in terms of
domain walls.