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Experimental investigation of the molecular ions of the xylenes
Author(s) -
Curtis J. M.,
Boyd R. K.,
Shushan B.,
Morgan T. G.,
Bey J. H.
Publication year - 1984
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210190502
Subject(s) - ion , kinetic energy , chemistry , fragmentation (computing) , mass spectrometry , quadrupole mass analyzer , isomerization , polyatomic ion , ionization , reaction mechanism , range (aeronautics) , atomic physics , collision induced dissociation , quadrupole , photochemistry , analytical chemistry (journal) , tandem mass spectrometry , physics , materials science , organic chemistry , computer science , chromatography , quantum mechanics , composite material , catalysis , operating system
A mass spectrometric method of distinguishing between molecular ions of the three isomeric xylenes (dimethylbenzenes) was sought, in light of recent findigs that photoexcited ions could be distinguished via measurements of kinetic energy release accompanying expulsion of a methyl radical. Provided the molecular ions are formed with low internal energies, reproducible differences were found between relative intensities of collision induced reactions of higher critical energies, than for methyl expulsion. These differences exist both for collision energies in the kilovolt range (double focusing mass spectrometers) and in the range of a few tens of volts (triple quadrupole instrument). Though statistically significant, these differences were small. The mechanism of isomerization and fragmentation was investigated via isotopic labelling studies and measurements of kinetic energy release. Most of the present findings can be rationalized in terms of the most recent version of established mechanisms for reactions of ionized methylbenzenes.