The electron impact-induced fragmentation of 2,2-dimethyland 2-ethyI-l,findandione, 1 and 2, and their isomers, 3-isopropylideneand 3-propylidenephthalide, 3 and 4, respectively, was studied in detail by mass-analysed ion kinetic energy (MIKE) and collision-induced dissociation (CID-MIKE) spectrometry, including 'H and I3Clabelled analogues of 1 and 2. In all regimes of internal energy, the mol...
