Two-centre interference effects on the Thomas two-step scattering mechanisms

The charge transfer process in the collision of fast protons with hydrogen molecules is theoretically investigated using the second-order Born approximation with correct boundary conditions. In addition to two first-order terms, the present calculations include the three second-order terms which correspond to the Thomas two-step scattering mechanisms. The interference effects, due to the scattering of the particles from two atomic centres, on the electron capture differential cross sections vary significantly with the orientation of the molecule and with the impact energy. After the averaging over all molecular orientations the interference patterns disappear but the Thomas peak becomes more pronounced. These patterns are also apparent in the differential cross sections as a function of the angle between the molecular axis and the incident beam direction. The integrated cross sections are calculated and the results are compared with available experimental data.