Collision-induced decompositions of aromatic molecular ions

Abstract

The collision-induced decompositions of the molecular ions of a number of aromatic compounds have been studied in a double-focusing mass spectrometer. After the ions had been accelerated through a potential difference of 8 kV, they collided with neutral species in the analyzer tube at a pressure of 7 × 10 −6 torr. A collision-induced metastable mass spectrum was produced which was found to be qualitatively similar to the electron-impact mass spectrum obtained using 50–70 V electrons. The observations support the view that collision-induced metastable transitions proceeds by transfer of energy to the electrons of the ion followed by subsequent unimolecular fragmentation of the excited ion.