Overview of Ionization Mechanisms

Abstract

To introduce the basic feature of the ionization mechanisms, in Fig. 2.1 we show a relatively simple electron spectrum indicating various characteristic phenomena. The data refer to electron emission cross sections calculated for the collision system 25-MeV/u Mo⁴⁰⁺ + He at an observation angle of 5° with respect to the incident beam direction [Stolterfoht et al. (1987)]. The theoretical method used in the calculations and the spectral structures of the results will be discussed in detail in the next sections, therefore, only a short description will be given here. The low-energy region is attributed to electrons produced in soft collisions (SC). At the high-energy end of the spectrum the pronounced peak is due to binary-encounter (BE) collisions. The structure labeled ECC is associated with the process of electron capture to the continuum. The region between the ECC peak and the SC shoulder is attributed to two-center electron emission (TCEE). This region is rather extensive, particularly for high-energy projectiles.