RESUMEN
The reactions of resonant electron capture by the molecules of benzene nitroderivatives has been studied in the gas phase. Some fragment negative ions were found to be unstable with respect to electron autodetachment. This circumstance has been used for the determination of their structure. In particular, it has been established that the low measured appearance energy of neutral component of [M-H](-) ion beam is a result of isomerization of nitrobenzenes' molecular ion, leading to the 2-nitrosophenol structure with the subsequent formation of the phenoxide anion in the autodetaching state. The effective yield curves of some types of fragment ions demonstrate fine vibrational structures, testifying the predissociation mechanism of ion formation. For all detected ions, the absolute cross sections of formation have been measured.
RESUMEN
This paper reports a study of resonant dissociative electron attachment (DEA) to the phenol, chlorobenzene, p-, m-, and o-chlorophenol molecules. On the basis of spectroscopic and thermochemical approaches the resonant states of the molecular negative ions (NIs) and the structures of some dissociative decay products are assigned. In the electron energy range up to 3 eV, DEA processes are determined by the two 2[pi*]-shape resonances resulting mainly in formation of [M-H]- and/or Cl- ions. At higher electron energies the energy correlation between peaks in the negative ion effective yield curves and bands of UV spectra allowed identification of the core-excited resonances. The peculiarities of Cl- ion formation and the vibrational fine structure on the effective yield curves of the [M-H]- ions are discussed. The mass spectrometric procedures for measurement of relative cross sections for NI formation are described.