Selective adsorption resonances at rainbow conditions in the scattering of atoms by stepped surfaces: application to the He/Cu(117) system

For stepped surfaces, dynamics is not parity reversal invariant with respect to the step configuration and the way the atomic beam approaches the surface, downstairs or upstairs scattering, should dramatically change rainbow patterns. We show that only one close-coupling calculation provides us information of the two possible scatterings at once. Furthermore, it is possible to find some incident conditions where surface rainbow is displayed for both configurations. At the same time, if resonances are analysed at rainbow conditions, we could enhance resonant features in the diffraction channel displaying rainbow. An application to the study of diffraction of ⁴He atoms by the Cu(117) surface is presented.