What does the term "excitation" mean in the context of radiation?

The term "excitation" in the context of radiation pertains to the process where an electron within an atom absorbs energy and transitions to a higher energy state without being ejected from the atom. This means that while the electron has gained energy, it has not lost its bond to the nucleus, which distinguishes it from ionization, where an electron is completely removed from the atom. When radiation interacts with matter, this energy transfer can occur, resulting in the electron temporarily occupying a higher energy level.

Understanding excitation is critical in radiation safety and understanding how radiation interacts with biological tissues, as it can lead to various effects, including chemical changes within the cell that may or may not result in damage. Recognizing that excitation does not involve the complete destruction of atoms or ionization helps clarify the different interactions that radiation can have with matter.