A coupled electron and ion spectrometer for investigating molecular ion fragmentation

Abstract

A cylindrical mirror analyzer (CMA) has been designed for analyzing the energy of the electrons emitted during the ionization process in a crossed electron beam and target gas jet geometry. The CMA is axially coupled to a single field Wiley–McLaren ion time-of-flight spectrometer for studying dissociation dynamics of molecular ions with a check on the participating electronic states. Coincidence detection of energy-selected Auger electrons and the fragmented molecular ions is performed in the experimental setup to obtain detailed information on dissociation dynamics for different electronic states of a di-cation. Electron beams of energy 0.1–5 keV can be used as projectiles for this study. The contribution to the Auger peak from electrons due to direct ionization limits the selectivity of the electronic state. Even with the limitations, the apparatus has a potential for state-selective studies. The details of the setup have been described here along with some selected examples of state selectivity with Ar and CO2 targets.