| Abstract
| - A combination of the “pickup” technique and a double focusing,high-resolution mass spectrometer havebeen used to generate and study the chemistry of cluster ions of theform Mg+(CH3OH)nand [Mg(CH3OH)n]2+, for n in therange 1−20. The singly charged ions exhibit a switch inintensity between Mg+(CH3OH)n andMg+OCH3(CH3OH)n-1at n = 3, which is attributed to an increase in stabilityof the polarized ion[Mg2+−OCH3-] as moremethanol molecules are added to the complex. No doubly chargedions are observedfor n =1, and the mass spectrum is dominated by parentions rather than fragments when n ≥ 2. Foreachof the two types of ion, the principal unimolecular (metastable) decaychannel is the loss of methanol. Withthe introduction of a collision gas, a very wide range of reactionproducts is observed for the smaller singlycharged ions, with the main fragments beingMg+OCH3, Mg+OH, andMg+H, which are formed, in somecases, in the presence of additional methanol molecules.Collisional fragmentation of the doubly chargedions is most often accompanied by Coulomb explosion in which chargeseparation follows the breaking ofcovalent bonds. However, in some instances the measured kineticenergy releases for the latter process arevery much lower than expected, and it is suggested that excess energyis being carried away by very lightfragments, e.g., H and H2. Some of the reactionsobserved for[Mg(CH3OH)n]2+ions can be accounted forby assuming a range of anion transfer processes.
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