Electron capture-induced decomposition (ECID): A new method to study electron-capture collisions

Abstract

A new method for the study of electron-capture collisions of doubly charged polyatomic ions is discussed. In the collision, not only electron transfer, but also excitation may take place. If so, the singly charged product ion will fragment and this fragmentation will be characteristic of both its structure and its internal energy. The principle of the experiment is to select a doubly charged ion beam, collide it on a neutral gas and look at the fragmentation following electron capture. The process, in analogy with collision-induced decomposition, may be called electron capture-induced decomposition (ECID). The difficulty with the experiment is that there are various interference reactions, which are discussed in detail. From the ECID process, a wide range of information on the collision complex, threshold energetics, the electronic states of the reactants, total and differential cross-sections, the internal energy distribution in the product ions and, above all, on the energy transfer in the collision can be learned. In connection with this, a new method to determine internal energy distribution is also discussed.