OXYGEN-INDUCED SURFACE (2X2)P4G RECONSTRUCTION OF RH(001)

The room-temperature oxygen-induced (2 x 2)p4g clock reconstruction of Rh(001) has been investigated by low-energy alkali ion scattering, re coiling spectrometry, low-energy electron diffraction (LEED), and thre e-dimensional classical scattering simulations. The oxygen atoms are c onfirmed to be in the fourfold hollow sites to produce the glide plane symmetry of the substrate observed in the LEED pattern. Quantitative values for the geometrical parameters were obtained by using a reliabi lity R-factor analysis to compare the experimental and simulated azimu thal scans. The lateral clockwise-counterclockwise displacement of the surface rhodium atoms is Delta x = 0.2 +/- 0.1 Angstrom and the oxyge n height above the substrate is Delta h = 0.6 +/- 0.1 Angstrom. The dr iving force for this clock reconstruction is discussed and compared wi th previous results on the Ni(001)-(2 x 2)p4g-C surface. [SO163-1829(9 8)07139-2].