The physics of electronic and atomic collisions

Almost as soon as quantum theory was developed to explain atomic structure, it was applied to problems of the scattering of electrons by atomic systems. Early efforts were devoted largely to determining whether or not the new picture of the atom was consistent with some of the results obtained in scattering experiments. For example, Faxen and Holtzmark developed their method of describing scattering in terms of phase shifts to explain the Ramsauer effect. The crudest approximations indicated that, in a general way, the wave‐mechanical picture was a satisfactory one for describing continuous, as well as discrete, spectral phenomena, and there the matter rested.