Surface crystallography from low-energy ion backscattering angular distributions

A new method for obtaining the arrangement of atoms at an ordered surface and for determining surface relaxations (to within 2% of interplanar spacings) by use of low-energy ions is presented. The method is illustrated with a computer simulation to generate the backscattered intensity distribution for 3-keV He+ ions normally incident on a Cu(001) surface. When displayed on a position-sensitive detector, the total backscattered yield would reveal blocking-cone features that are real-space images of surface atoms