Collision-Induced Dissociations in the Mass Spectrum of Methane

Abstract

The mass spectrum of methane has been investigated in the pressure range 1×10—7 to 5×10—5 mm of Hg. A number of diffuse peaks were observed at nonintegral masses. These arise from dissociation of various ionized methane fragments on collision with residaul methane gas in the field-free region of the mass spectrometer. The linear pressure dependence of their relative abundance points to single-collision processes. No multiple-collision processes or truly unimolecular metastable transitions were observed. A parallel between electron impact and collision-induced dissociation is pointed out.