| Autor: |
Zappey, Herman W., Drewello, Thomas, Ingemann, Steen, Nibbering, Nico M.M. |
| Zdroj: |
International Journal of Mass Spectrometry and Ion Processes; June 1992, Vol. 115 Issue: 2-3 p193-204, 12p |
| Abstrakt: |
The collision-induced dissociation (CID) and neutralization-reionization (NR) mass spectra of dimethylhalonium ions ((CH3)2X+, X = F, Cl, Br and I) with 8 keV translational energy have been recorded. The (CH3)2F+ion decomposes following collision with O2predominantly by loss of methane. The loss of a methyl radical competes with methane elimination in the reactions of the (CH3)2Cl+and (CH3)2Br+ions, whereas the (CH3)2I+ion fragments mainly by elimination of a methyl radical. Formation of an X+ion either by a reductive elimination forming ethane as the neutral product and/or by the consecutive loss of two methyl radicals occurs to some extent for the (CH3)2Br+and (CH3)2I+ions. Neutralization of the dimethylhalonium ions by collision with Xe does not result in dimethylhalogen radicals which persist on the microsecond time scale of the experiment and/or survive reionization by collision with O2. The NR process for the dimethylfluoronium ions results mainly in the formation of CH2F+ions and to a lesser extent of CH3F.+ions, whereas the CH2X+ions are less abundant than the CH3X.+radical cations in the NR experiments with the other halonium ions. The formation of relatively more abundant CH3X.+ions than of CH2X+ions in the NR experiments as compared with the CID experiments suggests that the predominant reaction accompanying neutralization of the halonium ions with Xe is a simple cleavage to form a methyl radical and a CH3X molecule. The NR process yields in all instances X+ions, whose relative abundance increases on going from (CH3)2F+to (CH3)2I+. |
| Databáze: |
Supplemental Index |
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