Ionization by Nuclear Transitions

Abstract

Ionization and excitation in an atom induced by nuclear processes [1,2] within that atom exemplify the so-called single step and two-step mechanisms. The former is characterized as a sudden shaking transition of the composite nucleus-atom system, analogous to shaking in photoemission. In the latter process the charged particles emitted in a nuclear decay transfer energy by a relatively slow “direct collision” final state interaction with atomic electrons. These are not truly distinct mechanisms; rather they are labels for the extremes of the time spans involved in different types of nuclear decays. In some theories they are even coherent interactions. For either the shaking or direct collision processes, we can give a phenomenological description of an ionization event that will apply to both types.