Microscopic theory of the imaginary part of the nucleus-nucleus potential

A model to microscopically construct the absorptive part of the optical potential between heavy ions is reviewed. The main contribution to this potential comes from the single nucleon transfer channels and from the nuclear excitation of surface modes. The first mechanism gives rise to a long range component with diffusivity a ≅ 0.6 fm. whilst the second gives rise to a short range component with a ≅ 0.3 fm. The application of this model to the study of the elastic scattering angular distribution of the 16O + 28Si will be discussed and it will also be shown how this model can account for the evolution of the backward rise in the elastic angular distributions of the different Si isotopes. The origin of the imaginary coupling potential for inelastic scattering will also be outlined. (Auth.)