The first hundred years of radiation studies have greatly clarified th
e chemical processes that are induced by radiation. While the fundamen
tal ionization processes are similar in all systems, properties of the
medium such as phase, polarity and composition can greatly affect the
chemistry. In all systems, one needs to understand what chemical spec
ies are formed, what the internal energies are, how they are dispersed
spatially, and what reactions can occur. In this review, the progress
that has been made in understanding the chemistry that occurs after a
radiolysis event for liquid water is outlined as an example of how pr
ogress has been made in radiation chemistry. (C) 1995 by Radiation Res
earch Society