annihilation

https://doi.org/10.1351/goldbook.A00366
  1. (in radiochemistry) An interaction between a particle and its @A00401@ in which they both disappear.
    Source:
    Orange Book, 2nd ed., p. 211 [Terms] [Book]
  2. (in photochemistry) Two atoms or molecular entities both in an excited @ET07026@ interact often (usually upon collision) to produce one atom or molecular entity in an excited @ET07026@ and another in its ground @ET07026@. This phenomenon (annihilation) is sometimes referred to as @E02111@.
    See:
    singlet-singlet annihilation
    ,
    spin conservation rule
    ,
    triplet-triplet annihilation
    Source:
    PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2228 [Terms] [Paper]