ABSTRACT
In order to determine the chemical state, i.e., the oxidation state and bond properties, of an element in entities constituting radioactive or nonradioactive matter, it is necessary to use a probe that is sensitive to the organization of the atomic electrons. Such a probe is offered by the radiations emitted in situ, provided their properties depend on the electronic environment. Alternatively, a positron emitter can be introduced into the system and the properties of the annihilation radiation can be investigated. In a sense, the positron can be considered as a "radioactive" tracer of the electron.
