Radiolysis - Radiolysis

In a broad sense, it is a general term for chemical changes that occur as a result of radiation acting on a substance, but it often refers to cases where radiation causes a decomposition reaction that produces decomposition products. However, it is also used to refer not only to decomposition reactions, but also to cases where polymers or isomers are produced as a result. The effects of radiation on substances are as follows:
(1) The process of radiation energy absorption by matter at the very beginning and the processes that follow immediately after it (physical steps),
(2) The subsequent, overlapping physicochemical steps of ionization, excitation, and interaction of atoms and molecules with surrounding atoms and molecules.
(3) After all of these intermediates have reached thermal equilibrium, subsequent chemical changes (chemical steps) such as radical reactions occur.
Radiation physics focuses on (1), while radiation chemistry focuses on (2) and studies the chemical effects of (1) and (3).

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

広義には，放射線が物質に作用した結果起こる化学変化を総称していうが，放射線の作用によって分解反応が起こり，分解生成物を生じる場合をさすことが多い．ただし，分解反応のみならず，結果として重合体あるいは異性体を与える場合にも用いられる．放射線の物質への作用は，
(1)ごく初期の物質による放射線エネルギー吸収過程とそれにただちに続いて起こる過程(物理的段階)と，
(2)これと一部分重複してこれに続く原子，分子のイオン化，励起，およびこれらと周囲の原子，分子との相互作用(物理化学的段階)，
(3)さらにこれらの中間体がすべて熱平衡化してしまったのちに，続いて起こるラジカル反応などの化学変化(化学的段階)，
とに分けられる．(1)を中心に研究を行うのが放射線物理学であり，(2)に中心をおいて(1)および(3)をも含めて化学的効果を研究するのが放射線化学である．

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