OBSERVATION OF ANISOTROPIC PCI EFFECTS AT HIGH EXCESS ENERGIES

A coplanar electron coincidence spectrometer has been used to measure Auger lineshapes in coincidence with the scattered electron produced after electron impact ionization of the 2p shell in argon. The coincident lineshapes have been measured at an excess energy which is close to the nominal Auger energy. The L3-M23M23(1D2) lineshape was measured for two different emission angles, -95-degrees and 132-degrees, of the Auger electron. The angles chosen correspond to the recoil and binary regions, respectively, of the triple differential cross section for 2p ionization of argon. Additional structure was observed in the coincidence Auger lineshape at one angle (-95-degrees), consistent with an angular dependence of the post collision interaction.