With 28 FiguresWhen a fast charged particle is incident on an atom or a molecule, generally one or more electrons are ejected in the collision. The production of electrons by ion impact is of principal interest in many branches of physics and related sciences. Thus, electron spectroscopy in ion-atom collisions has received a great deal of attention in the past. Atomic structures as well as dynamic excitation mechanisms have been studied by electron detection. These efforts have revealed important information about the electron production mechanisms in collisions between ions and atoms.The purpose of the present chapter is to review recent studies of inner-and outer-shell excitation in ion-atom collisions accompanied by electron emission. Emphasis is given to the excitation mechanisms rather than to the atomic structure aspects. Projectile energies in the keV range as well as in the MeV range will be treated. The amount of work done in this field is tremendous so that no attempt is made to give a complete summary here. For instance, the present chapter will be restricted to projectile energies higher than about 5 keV, and electron measurements using the beam-foil method are not included. Also, instrumental details will not be given; the discussion of the apparatus is left to the original references. In this chapter, specific topics are selected which are instructive for the understanding of electron excitation mechanisms in ion-atom collisions.For reasons of convenient representation, this chapter is structured to describe excitation of outer-shells and inner-shells separately. This choice is somewhat arbitrary, as the related excitation mechanisms are rather similar in the two cases. However, differences occur in the experimental methods for studying outer-and inner--shell excitation by electron spectroscopy. Generally, in the latter case, Auger electrons of well-defined energies are detected, whereas in the first case continuous electron spectra are measured.Following the background Section 5.1, a brief survey about electron production mechanisms is given in Section 5.2. Then, more detailed aspects of the field will be discussed. Section 5.3 is devoted to outer-shell ionization of the projectile and the target atom. In Section 5.4 the inner-shell excitation of the collision particles is treated. A few examples of Auger spectra will be given and, then, inner vacancy production mechanisms will be discussed within the framework of excitation models, such as direct excitation and electron promotion. Literature till spring 1976 is taken into consideration.
I. A. Sellin (ed.), Structure and Collisions of Ions and Atoms