Soft potential and van der Waals effects in He-KCl(001) grazing-incidence fast atom diffraction.

G.A. BOCÁN; H. BREISS; S. SZILASI; A. MOMENI; E.M. STAICU CASAGRANDE; E.A. SANCHEZ; M.S. GRAVIELLE; H. KHEMLICHE

Helsinki

Conferencia; ICACS 29 -SHIM 11; 2022

ICACS

In our poster we address, both experimentally and theoretically, the very grazing scattering of He atoms off KCl(001), for incidence along the h100i channel. Our theoretical model combines a semiquantum description of the scattering dynamics and a high-precision interaction potential. By means of a thorough analysis of the quantum phase for in-plane scattering and rainbow trajectories, we are able to connect the presence of a physisorption well with the significant enhancements of the corrugation and rainbow angle, relative to the hard corrugated wall predictions. We trace this connection to soft potential effects on the incident and scattered beams due to their traversing of the physisorption well. Finally, we show that the inclusion of vdW interactions in the potential improves the theoretical accord with experiments for both the corrugation and the rainbow angle [1]. [1] G.A. Bocan, H. Breiss, S. Szilasi, A. Momeni, E.M. Staicu Casagrande, E.A. Sánchez, M.S. Gravielle, and H. Khemliche, Phys. Rev. B 104 (2021) 235401