Collisionhyphen;Induced Dissociations in the Mass Spectrum of Methane

摘要

The mass spectrum of methane has been investigated in the pressure range 1times;10mdash;7to 5times;10mdash;5mm 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 fieldhyphen;free region of the mass spectrometer. The linear pressure dependence of their relative abundance points to singlehyphen;collision processes. No multiplehyphen;collision processes or truly unimolecular metastable transitions were observed. A parallel between electron impact and collisionhyphen;induced dissociation is pointed out.