Theory

1.1 Quantum Reflection - semiclassical approach - sam's code(brief explanation about two competing theoretical model)

 Quantum reflection is a quantum mechanical phenomenon in which a particle is reflected by the attractive part of the van der Waals potential as depicted in Fig. 1(a). Unlike classical reflection, a particle does not need to collide with the surface because quantum reflection typically occurs tens of nanometers away from the surface. In order to investigate quantum reflection experimentally, the particle’s kinetic energy perpendicular to the surface must be sufficiently small. One way to achieve this prerequisite is using a grazing incidence condition. Fig. 1(b) shows a sketch of the grazing incidence condition. In typical experimental conditions, a grazing incidence angle qin of a few mrads provides a sufficiently small z-component kinetic energy Ez. perpendicular to the surface
--- least squares analysis (logarithmic)

1.2 Matter-wave diffraction from a periodic array of half planes  - original/ Attenuation

- the possibility to observe the diffraction of N2 of He3 - theoretical curve with the square-wave grating