LEED STRUCTURE DETERMINATION OF 2 ORDERED SURFACE ALLOYS - CU(100)-C(2X2)MN AND NI(100)-C(2X2)MN

The structure of the Cu(100)-c(2 x 2)Mn and Ni(100)-c(2 x 2)Mn phase w as determined by a quantitative low-energy electron diffraction (LEED) intensity analysis. These structures are ordered surface alloys which form after deposition of 0.5 ML Mn on the clean Cu(100) and Ni(100) s urface above 270 K. The alloy layer shows a pronounced corrugation in which Mn atoms in the first layer are displaced outwards by 0.30 +/- 0 .02 angstrom on Cu(100) and 0.25 +/- 0.02 angstrom on Ni(100). The int erlayer distance from the Cu (Ni) atoms to second layer Cu (Ni) atoms is close to the Cu(100)-[Ni(100)] bulk interlayer spacing of 1.807 ang strom (1.76 angstrom). Deeper interlayer distances are also very simil ar to the respective bulk value.