Test of the interatomic potential in the eV-region by glancing-angle scattering of He-atoms from Fe(001)

We report on experimental observation of multimodal angular distributions o f 15 keV He-0-atoms scattered under glancing angles from an Fe(0 0 1) surfa ce along a [0 0 0] surface direction. Based on classical molecular dynamics computer simulations of atom trajectories we deduce the He-Fe interaction potential in the eV-energy range. Our experiments visualize the transition from axial to planar surface channeling. For our dynamical row-model to des cribe the experimental data well, we construct a mixed potential from two w ell-known potentials in the literature, the "universal" potential for large distances and the "individual" potential for close particle separation. In addition, the shift of the experimental angle spectra with respect to the calculated shows elastic horizontal bend of the real atomistic rows due to the scattering and about 10 times smaller vertical displacement. (C) 2001 E lsevier Science B.V. All rights reserved.