(1XN) RECONSTRUCTION OF THE RH(110) SURFACE WITH N = 2, 3, 4, 5

The formation and reduction with hydrogen of ordered oxygen layers on Rh (110) has been studied by means of LEED, Auger spectroscopy and thermal desorption. We show that it is possible to prepare clean, (1 x n) reconstructed Rh (110) surfaces by suitable thermal and chemical treatment. Adsorption of oxygen on a Rh(110) surface followed by heating to 700 K results in (2 x 3), (2 x 2)p2mg or c (2 x 2n) structures (n = 3, 4 and 5), depending on oxygen coverage. Reduction by hydrogen at 370 K results, respectively, in (1 x 3 ), (1 x 2) and (1 x n) structures which are oxygen- and hydrogen-free as judged by AES and TDS. The (1 x n) structures are metastable and revert to (1 x 1) at temperatures above 480 K. These results offer the possibility of studying a clean Rh (110) surface both in its unreconstructed state and in a variety of reconstructed phases.