Kinetic energy release in metastable ions from β‐keto esters

The kinetic energy release, T, in metastable ion transitions accompanying the main fragmentation reaction by electron impact has been determined for methyl‐, ethyl‐ and propyl‐pivaloyl acetates. The measurements have been made using a MAT 311 mass spectrometer with inverse Nier–Johnson geometry, by high voltage and mass‐analysed ion kinetic energy methods. The peak width at 50% height has been used in the calculations. The T values and the shape of the metastable peaks are correlated to reaction types and to the alcohol radical.