The surface composition, structure, and oxygen-induced reconstruction
of Cu3Pt(110) have been investigated by low-energy ion scattering, rec
oiling spectrometry, and low-energy electron diffraction. The surface
composition of the top two layers was determined from Li+ single-scatt
ering intensities using selective scattering geometries with calibrati
on measurements on reference standards. Under thermal equilibrium cond
itions, the measurements consistently showed a surface composition of
82% Cu-18% Pt in the first layer, while the second layer was composed
almost entirely of Cu. From computer simulations and analysis of the s
hadowing critical edges, the first interlayer spacing was found to be
contracted by about 6+/-2%. whereas the surface Pt atoms were buckled
outward by 0.1+/-0.06 Angstrom. Adsorption of oxygen on the clean Cu3P
t(110) surface at room temperature followed by subsequent annealing le
ads to a (2 x 1) reconstruction. By Li+ ion scattering and negative O-
recoil measurements the oxygen-induced structure was determined to be
a missing-row type reconstruction which involves loss of Pt from the
first layer in a thermally activated place exchange with Cu atoms. The
first interlayer spacing was expanded by 23+/-10% relative to the ide
al spacing, while the O atoms were located 0.1+/-0.1 Angstrom below th
e first Cu layer. The structural features found are discussed and comp
ared with previous results on the Cu(110)-(2 x 1)-O and Cu3Au(110)-(2
x 1)-O surfaces. (C) 1998 Elsevier Science B.V. All rights reserved.