Surface-scattering study of the interaction potential of He atoms with the step edges of the Cu(211) and Cu(511) vicinal surfaces

The diffraction intensities of He atoms scattered from vicinal Cu(211) and Cu(511) surfaces have been measured with a high angular resolution over a wide range of incident energies from 8 to 82 meV. Close-coupling scattering calculations with a corrugated Morse potential were performed to obtain the corrugation parameters for the first three complex Fourier coefficients. The energy-dependent corrugation profiles determined from the best fit indicate that the corrugation predicted by a simple hard-sphere model is considerably smeared out at the small electron densities far from the surface probed by the He atoms. A comparison with Eikonal calculations demonstrates that hard corrugated wall Eikonal models are not adequate for the structural analysis of stepped surfaces. copyright 1996 The American Physical Society