ON THE DISSOCIATION PATHWAYS OF NITROBENZENE

The fragmentation of nitrobenzene has been studied in the wavelength r ange 225-275 nm using a single dye laser, frequency doubled, in conjun ction with a time-of-flight (TOF) mass spectrometer. The parent (C6H5N O2+), nitrosobenzene (C6H5NO+), phenoxy (C6H5O+) and phenyl (C6H5+) io ns were all observed in addition to many other lighter daughter fragme nts. The formation of the nitrosobenzene, phenoxy and phenyl ions are all explained invoking pathways where dissociation of the parent molec ule from an excited state takes place first, followed by ionization af ter the absorption of further photons (DI) by the fragmented neutrals. Ionization of the parent molecule to states which are dissociative (I D) can explain the increase in the production of phenyl ions at wavele ngths shorter than 230 nm.