Helium scattering from metal surfaces: potential determination and crystallography

We describe a method for determining the interaction potential between a helium atom and a metal surface from diffraction data. Results are presented for He/Ni(110) and He/Cu(110). For He/Cu(110) the potential 3s in good agreement with a first principles calculation but this is not true for He/Ni(110). We also show that a surface relaxation of 10% produces measurable changes in intensities.