McLafferty rearrangement

in mass spectrometry
https://doi.org/10.1351/goldbook.M03772
β-Cleavage with concomitant specific transfer of a γ-hydrogen atom in a six-membered @T06468@ in mono-unsaturated systems, irrespective of whether the @R05194@ is formulated by a radical or an ionic mechanism, and irrespective of the position of the charge.
Source:
Orange Book, 2nd ed., p. 207 [Terms]