Electron-ion spectroscopy: a probe of molecular dynamics

Coincidence techniques are briefly reviewed in this paper. Using illustrative examples, we show that fragmentation dynamics are revealed through coincidence measurements where the internal energy of the ion is selected by electron energy analysis. A new coincidence set-up is described using a double toroidal electron analyzer facing a short time of flight mass spectrometer. New measurements on (NNO)-N-14-N-15 molecule after N(c)ls (central) or N(t)ls (terminal) core ionization, clearly show a specific dissociation channel. On larger molecules, the origin of selective fragmentation is pointed out by direct comparison of the mass spectra obtained in coincidence either with C12p Auger electrons or Br3d Auger electrons. (C) 1998 Elsevier Science B.V. All rights reserved.