Gas–surface scattering cross section by the complex coordinate method

The elastic scattering cross section of atomic beams from periodically rough solid surfaces is computed by means of a quantum-mechanical approach, based on the complex coordinate method. The effect of a threshold singularity in the specular scattering of helium beam from Cu(110) is found to yield a step structure in the scattering pattern, which should be observable experimentally. The calculated specular scattering pattern obtained, using a corrugated Morse potential with a simple one-dimensional corrugation function, is in a remarkable agreement with the experimental resonance line shapes of He beams from Cu(115) over the entire range of incident angles.