Optical Potential for Li-HBr Collisions at Low Energies

A molecular optical potential has been used to reproduce the quenching of glory undulations in the total cross section of Li and HBr colliding at relative velocities ${10}^5 \mathrm{cm}/sec<~v<~{3.10}^5 \mathrm{cm}/sec$. The experimental results over the whole velocity range are well fitted by a ${\mathcal{r}}^{-12\mathrm{}}$ law for the imaginary part of the potential. Complex phase shifts, opacity function, and elastic angular distribution have been calculated with this potential. Comparison with calculations using a real potential shows rainbow and supernumerary rainbow maxima and an increase of intensities at large angles in both cases. The main effect of inelastic transitions is to decrease the scattering intensity at large center of mass angles.