Surface atomic structure of the (√3x√3)R30°-Sb reconstructions of Ag(111) and Cu(111)

We present an X-ray diffraction structure analysis of the (root 3 x root 3)R30 degrees reconstructions of Ag(lll)-Sb and Cu(lll)-Sb surfaces, We find these structures to be very similar. Contrary to previous reports, we find that all top layer atoms reside at stacking fault positions. Each (root 3x root 3)R30 degrees surface unit cell contains one substitutional Sb atom. We determined the out-of-plane relaxations of the top layer atoms and the in-plane distortions in the second layer. For coverages below 1/3 monolayer, the Sb atoms are embedded randomly at fee positions in the top surface layer. (C) 1998 Elsevier Science B.V. All rights reserved.