Rotational excitation of tetrahedral and octahedral molecules caused by electron and positron impact - Momentum transfer, integral and differential cross sections

The study of rotational transitions in octahedral molecules induced by positrons has a major role in the development of positron traps, since the SF₆ has been pointed out as the most efficient buffer gas. Rotational excitation cross sections of tetrahedral and octahedral molecules caused by low energy positron/electron impact are the subject of this work. We developed a scattering model considering the Born approximation and the asymptotic multipole potential. These assumptions permitted us to achieve analytical expressions for rotational integral, momentum transfer and differential cross sections. We have applied this model to CH₄ and SF₆ molecules. We have found good agreement for positron and marginal agreement for electron interactions. The model can be improved with the inclusion of exchange effects and the distortion of the scattering wave function