Adsorbate-induced reconstruction of Rh(110)1×2-H

Abstract

The Rh(110)1×2-H superstructure is investigated by means of a low-energy electron diffraction intensity analysis. Additional to the usual reliability-factor (r-factor) comparison of experimental and calculated intensities, the ratio between average intensity levels of fractional- and integer-order spot intensities is used as a guide to determine the correct structure. A weak adsorbate-induced reconstruction is necessary to produce both the experimentally observed intensity levels and a satisfying theory-experiment fit (Pendry r factor, R=0.44). The detected shift-buckling model results by hydrogen adsorption at every second [110] rhodium row. The latter is pulled out vertically of the surface and laterally displaced by 0.04 Å for both directions. Hydrogen atoms are positioned in nearly threefold-coordinated sites with a Rh-H bond length of 1.87±0.1 Å. .AE