Remember that ions contain charges, those charges could be positive or negative. So, the process of becoming atoms and molecules a charged would be ionizing radiation, because the concept of ionizing radiation is radiation with enough energy to remove tightly bound electrons from the orbit of an atom, causing that atom to become charged or ionized.
We have another type of radiation that can cause this too and it is particulate radiation because particulate radiation consists of ionizing radiation which contains alpha, beta, neutrons, and positrons particles and those particles have charges.