LARGE-ANGLE ELASTIC-SCATTERING OF ELECTRONS FROM AR+

Absolute angular differential cross sections have been experimentally determined for large angle scattering of a free electron by a positive ion for the first time. Data are presented for elastic scattering ove r the range 120 degrees-170 degrees from Ar+ at 3.3 eV. Interference e ffects are observed due to the competing short-range and Coulomb inter actions. The importance of interference and correlation effects is dem onstrated, and the consequent sensitivity of such measurements as a te st of theoretical approximations is discussed.