Fragmentation and mass spectra of Ketone

• The mass spectrum of a ketone generally has an intense molecular ion peak.
• Ketones fragment homolytically at the C-C bond adjacent to the C=O bond, which results in the formation of a cation with a positive charge shared by two atoms. The alkyl group leading to the more stable radical is the one that is more easily cleaved.

• If one of the alkyl groups attached to the carbonyl carbon has γ hydrogen, a cleavage known as a McLafferty rearrangement may occur.
  

lets interpret this spectrum