Theory of electron degradation and yields of initial molecular species produced by ionizing radiation

Ionizing radiations generate in matter a large number of energetic electrons, which in turn collide with molecules in matter, produce ions and excited states, and thereby degrade in energy. The description of the consequences of many collision processes to the electrons and to matter is the goal of the electron degradation theory. We summarize the current understanding of this topic, which is important as a basis of radiation chemistry and biology. In addition, we present an initial report of our new work, namely, a generalization of the Spencer–Fano theory to time-dependent cases.