DIRECT DETERMINATION OF ATOMIC POSITIONS ON THE CU(110)-(1X2)-H SURFACE

Results of a low-energy ipn scattering study of the H-induced 1 x 2 re construction of the Cu(110) surface are presented. The surface was bom barded with 6-keV Ar+ ions under a grazing angle of 5 degrees, 6 degre es, or 8 degrees; azimuthal scans of the yields of the scattered Ar an d recoiled Cu and H atoms emitted at a scattering angle of 45 degrees were measured. The scans were compared with the results of computer si mulations. We confirm that the surface is of the 1x2 ''missing-row'' t ype. Nine possible positions of H atoms at the Cu(110)-(1x2) surface f or different coverages were analyzed. The H atoms were found to be sit uated in one of the two possible trigonal hollow sites on the missing- row reconstructed surface. To obtain good fits to the experimental dat a, large thermal vibration amplitudes of the H atoms had to be assumed . These large amplitudes can be due to a nonharmonic potential. [S0163 -1829(98)05315-6].