NEUTRALIZATION AS A PROBE FOR IONIC STRUCTURES AND THE DISSOCIATIVE DYNAMICS OF ELECTRONICALLY EXCITED-STATES - THE NITROMETHANE CASE

The isomers nitromethane, aci-nitromethane, and methyl nitrite have been studied by neutralizing their radical cations in charge-transfer collisions with cesium and sodium atoms. Neutral molecules are formed in excited states with well-defined and substantial electronic excitation energies. Rapid dissociation occurs without relaxation to the electronic ground state. Neutral fragment mass spectra and fragment kinetic energy release distributions are recorded by using translational spectroscopy. Structures revealing simple cleavage reactions dominate the spectra. The power of this technique to distinguish between ionic isomeric structures is shown and the decay dynamics of the electronically excited neutral polyatomic molecules is discussed.