Collisionally-induced decompositions

Abstract

In the CH 4-CI mass spectra of aromatic hydrocarbons, fragment ions are observed which are attributed to collisionally-induced decompositions of (M + H) + ions. These decompositions occur in the region of intermediate pressure just outside the source of the mass spectrometer. Both rearrangement decompositions and simple fragmentations are observed. A simple instrumental modification to study these decompositions is described. The extent of collisionally-induced decomposition is proportional to the voltage applied to these ions in the region just outside the source. These processes can provide structural information for low-energy CI reagent gases and indicate the presence of certain functional groups in the molecules. The decomposition processes appear to be most easily interpretable in terms of decomposition of compounds in which the substituent is protonated.