Evanescent wave diffraction of multi-level atoms

Diffraction of multi-level atoms by an evanescent wave reflective diffraction grating is modeled by numerically solving the time-dependent Schr\"{o}dinger equation. We are able to explain the diffraction observed in experiments with metastable Neon. This is not possible using a two-level atom model. The multi-level model predicts sensitive dependence of diffraction on the laser polarization and on the intensity ratio of incoming and reflected laser beams.