A NEW METHOD FOR MEASUREMENT OF POSTCOLLISION INTERACTION EFFECTS IN ION ATOM COLLISIONS

We present a new experimental method for determination of the post-collision interaction (PCI) distortions of the lineshape of Auger electrons excited in ion-atom collisions. The method is based on the assumption that the excitation of Auger electrons from a target atom by electron capture on impact of singly charged ions is not influenced by PCI in regard to the the absence of charged outgoing particles. Consequently, by detection of Auger electrons following capture a reference line can be obtained which is free of PCI distortions. As a demonstration of the method we have studied the shape of the L3 -M2,32 (1S0) Auger line of argon excited by 0.7 MeV protons detecting the electrons in coincidence with the neutralized H0 atoms and without it. Further non-coincidence measurements determining the asymmetry of the L2,3-M(2,3)2 Auger lines as a function of the proton energy and observation angle have also been made. The results are in a qualitative agreement with the semi-classical theory of van der Straten and Morgenstern.