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. Closecoupling 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. @S0163-1829~96!00831-4#