Regge poles and the Watson-Sommerfeld transformation in low-energy atomic collisions

Abstract

The usefulness of complex angular momentum techniques is examined in the context of low-energy atomic collisions. For elastic e-Ar collisions at energies between 50 eV and 200 eV the observed structure in the differential cross sections is reproduced by the contribution from three Regge poles. For a Lennard-Jones potential representing p-Ar collisions the contributions from many poles are significant and the interference between these contributions leads to serious numerical difficulties in the application of the Watson-Sommerfeld transformation. The Remler model is shown to give a reliable phenomenological procedure for fitting measured differential cross sections for ion-atom collisions, even though the physical basis of the model is questionable.