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Electron-driven ionization of large methanol clusters in helium nanodroplets

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journal contribution
posted on 24.01.2014, 09:31 by Marcelo Goulart, Peter Bartl, Andreas Mauracher, Fabio Zappa, Andrew M. Ellis, Paul Scheier
The electron-driven ionization of helium droplets doped with pure methanol and ethanol clusters has been investigated for the first time using high resolution mass spectrometry. Large clusters are readily accessible by this route, with up to 100 alcohol molecules seen in the present study. The mass spectra for the doped helium droplets show many similarities with previous gas phase mass spectrometric studies of methanol and ethanol clusters. Thus the dominant ion products, at least for small clusters, are the protonated species H[superscript +](CH[subscript 3]OH)[subscript n] and H[superscript +](C[subscript 2]H[subscript 5]OH)[subscript n]. Likewise intra-cluster reaction is observed to produce H[superscript +](H[subscript 2]O)(CH[subscript 3]OH)[subscript n] and H[superscript +](H[subscript 2]O)(C[subscript 2]H[subscript 5]OH)[subscript n] ions. However, in helium droplets the observation of consecutive intra-cluster reactions is seen with product molecules containing up to five water molecules. The evidence points towards the proton locating on H[subscript 2]O to form H[subscript 3]O[superscript +], rather than the alcohol, despite the higher proton affinity of the latter. The behaviour of the H[superscript +](H[subscript 2]O)[subscript m](ROH)[subscript n] ion signals as a function of cluster size is consistent with the most stable cluster structures arising from a central H[subscript 3]O[superscript +] ion surrounded by two or more complete five-membered rings with the constituents held in place by hydrogen bonds.

History

Citation

Physical Chemistry Chemical Physics, 2013, 15 (10), pp. 3577-3582

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Chemistry

Version

VoR (Version of Record)

Published in

Physical Chemistry Chemical Physics

Publisher

Royal Society of Chemistry

issn

1463-9076

eissn

1463-9084

Copyright date

2013

Available date

24/01/2014

Publisher version

http://pubs.rsc.org/en/Content/ArticleLanding/2013/CP/c3cp43826k#!divAbstract

Language

en