Temporary negative-ion states in pyridine and diazine molecules

Results of electron scattering experiments using a transmission spectrometer are reported for the N-heterocyclic molecules: pyridine, pyridazine, pyrimidine and pyrazine. A number of resonant states are observed in the energy range 0.05 eV to 10 eV. Substituting an N atom for a CH radical in the benzeene ring is shown to remove the degeneracy of the two lowest empty π-orbitals. The derivative technique is applied to the 127° momentum analyser but none of the vibrational structure observed in an experiment using a trochoidal monochromator is detected. Reasonable agreement is reached for values of the first electron affinity.