Ionization and dissociation of diphenyl and condensed-ring aromatics by electron impact. III. Azobenzene

Abstract Mass spectra of azobenzene including metastable peaks at several electron energies have been obtained using a Consolidated Electrodynamics Corp. Type 21-110B double-focussing mass spectrometer. Appearance energies of several ions of interest have been measured using a Consolidated Electrodynamics Corp. Type 21–701 coincident-field mass spectrometer. An intense C 6 H 5 N 2 + ion was observed having an appearance energy of 9.75 eV. From the metastable peak at 60.6 mass units it was calculated that ∼1.4 kcal mol −1 was released in translation and that as much as 14 kcal mol −1 excess energy was involved at onset. At 11.9 eV the C 6 H 5 + ion is formed by successive loss of C 6 H 5 and N 2 from the parent ion. Very little excess energy is involved. The ions C 12 H 10 + , C 12 H 9 + and C 12 H 8 + are formed with very small intensity by successive loss of N 2 and two hydrogen atoms. The C 12 H 10 + ion is formed with large release of energy in translation. The C 12 H 9 + and C 12 H 8 + ions are formed with considerably less excess energy. The appearance and excess energies suggest that these ions may have the biphenyl—biphenylene structure.