SURFACE-STRUCTURE FROM ANGLE-RESOLVED SECONDARY-ION MASS-SPECTROMETRY - OXYGEN ON CU(001)

Measured angular distributions for O- and Cu+ ejected by 1500-eV Ar+-ion bombardment of chemisorbed oxygen on Cu(001) exhibit anisotropies which vary by greater than a factor of 2. Molecular-dynamics calculations of the ion-impact event agree well with experiment if the oxygen atom is placed in a fourfold coordination site 1.2-1.5 a above the Cu(001) plane. Angle-resolved secondary-ion mass spectrometry is proposed as a powerful new method for the determination of adsorbate positions. © 1979 The American Physical Society.