Rainbow structure and g–u-interference effects in the elastic scattering of low energy protons on deuterium and hydrogen atoms

Abstract

Elastic differential cross sections for the scattering of low energy protons (E_c.m.=11–142 eV) on H and D atoms have been obtained. The curves exhibit clearly rainbow structure, g–u oscillations and a type of rapid interference, if coherent scattering of both σ_g and σ_u potential curves is taken into account. For comparison, partial wave calculations have been performed using WKB phases and a two‐state (1sσ_g, 2pσ_u) approximation. The agreement with both experimental results and three‐state (1sσ_g, 2pσ_u, 2pπ_u) calculations of Knudson et al. is excellent, which implies that rotational coupling between the 2pσ_u and 2pπ_u potential curves can be neglected. It is shown that the reduced phases a=√E/2μN can be described as a single function of the reduced angle τ=Eϑ for all energies and both isotopes. This function agrees with both two‐state calculations of the authors and three‐state calculations of Knudson et al.