Probing di-nitrobenzene by low energy electrons: Identification of isomers via resonances in dissociative electron attachment

Free electron attachment to the three isomers of di-nitrobenzene (DNB) by means of a crossed electron molecular beam experiment with mass spectrometric detection of the anions is studied. In all three isomers, we detect long lived (metastable) non-dissociated parent anions which are formed at energies near 0 eV. In addition, all three compounds exhibit rich fragmentation patterns due to dissociative electron attachment (DEA). The resonance profiles of particular fragment anions in the energy range 0–10 eV differ substantially between the different isomers which can be used for an unambiguous identification of the individual isomer. Many of the DEA products observed at low energy arise from surprisingly complex reactions associated with multiple bond cleavages and structural and electronic rearrangement.