fragmentation

1. The heterolytic cleavage of a molecule according to the general reaction:
   
   where a-b is an electrofuge and X is a nucleofuge (which may emerge from the reaction in combined form), and the middle group affords the unsaturated fragment c=d. For example,
   
2. The breakdown of a radical into a diamagnetic molecule or ion and a smaller radical, e.g.
   
   
3. The breakdown of a radical ion in a mass spectrometer or in solution, forming an ion of lower molar mass and a radical, e.g.