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J. D. MOSLEY, T. C. CHENG AND M. A. DUNCAN, University of Georgia, Dept. of Chemistry, 1001 Cedar St, Athens, GA 30602.
The m/z=31 cation is produced by ionization and fragmentation of methanol, ethanol, dimethyl ether, etc. Two structures have been proposed, protonated formaldehyde (1CH2OH+) and the triplet methoxy cation (3CH3O+). The infrared spectrum of the mass 31 cation is obtained using infrared photodissociation spectroscopy with Ar tagging. The spectrum reveals the presence of two stable isomers, protonated formaldehyde (1CH2OH+) and the triplet methoxy cation (3CH3O+). The triplet methoxy cation has been studied extensively and is predicted to interconvert to protonated formaldehyde through an essentially barrierless process on a timescale much faster than our experiment (>100 µs). The presence of two structural isomers is verified by comparison of spectra from different precursors and spectra of different temperature ions from the same precursor.