COLLISION-INDUCED DISSOCIATION DYNAMICS OF THE ACETONE CATION - INTRACONVERSION OF TRANSLATIONAL AND ELECTRONIC-ENERGY

Collisional activation and dissociation of low-energy acetone ions have been studied using a crossed-beam tandem mass spectrometer. A small but significant fraction of acetone ions from 70 eV electron ionization are formed in long-lived excited A state. Ground state acetone ions are also collisionally excited to the A state via conversion of translational into internal energy. Two populations of collisionally excited ions are formed, one which is stable on the time scale of our experiments and one which dissociates into an acetyl ion and a methyl radical. These microscopically related reaction pathways demonstrate the unexpectedly facile interconversion of translational and electronic energy in low-energy collisions. © 1990.