Differential electron emission from multi-electronic targets under highly charged bare ion impact

S. BISWAS; D. MISRA; J. M. MONTI; C. A. TACHINO; R. D. RIVAROLA; L. C. TRIBEDI

Toledo

Conferencia; XXIX International Conference on Photonic, Electronic and Atomic Collisions; 2015

Study of doubly differential electron emission, in case of highly charged ion collision with atoms, can provide the microscopic details of the underlying electron dynamics. In this report, we provide a systematic study of the absolute double differentialcross sections (DDCS) of electron emission in ionization of He, Ne and Xe atoms under the impact of 5-MeV/u and 6-MeV/u C$^{6+}$ ions. An electrostatic hemispherical analyzer was used for detection of low energy (1-600eV) electrons over a wide range of angles (20º -150º ). The experimental data have been compared rigorously with the post and the prior forms of the CDW-EIS model. In general, the better agreement of the prior form compared to the post form indicates the role of the target passive electron dynamic screening effect for multi-electronic targets [1]. In case of the Xe target, several different features have been noticed. The energy distribution spectrum is dominated by different Auger transition lines right from the low energy region. Unlike He and Ne targets, the binary encounter peak in the angular distribution is almost absent. Besides, thenature of forward-backward angular asymmetry is also completely different from that of the He or Ne targets. As we approach the larger targets, the inner shell processes come into picture. This has been clearly seen from the estimates of sub-shell contributions to the total DDCS. In case of Ne, the electron emission spectrum is mostly dominated bywhereas for Xe, particularly in the higher energy region of the spectrum at extreme forward and backward angles, the inner shell ionizationdominates over the outer shell contribution. This explains some of the observed differences to some extent. It is also realized that the inclusion of different characteristic excitation processes like Auger process, or some collective excitation processes is necessary to completethe theoretical description of the electron dynamics in case of the larger multi-electron targets [2].[1] Biswas et al 2014 Phys. Rev. A 90 052714[2] Biswas et al 2015 (J. Phys. B; accepted)