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|Title:||Electron impact ionization of water-doped superfluid helium nanodroplets: observation of He (H2O)+n clusters|
Brereton, Scott M.
Ellis, Andrew M.
|Publisher:||American Institute of Physics (AIP)|
|Citation:||Journal of Chemical Physics, 2007, 127(13), 4303.|
|Abstract:||Electron impact mass spectra have been recorded for helium nanodroplets containing water clusters. In addition to identification of both H+(H2O)n and (H2O)n+ ions in the gas phase, additional peaks are observed which are assigned to He(H2O)n+ clusters for up to n = 27. No clusters are detected with more than one helium atom attached. The interpretation of these findings is that quenching of (H2O)n+ by the surrounding helium can cool the cluster to the point where not only is fragmentation to H+(H2O)m (where m ⩽ n−1) avoided, but also, in some cases, a helium atom can remain attached to the cluster ion as it escapes into the gas phase. Ab initio calculations suggest that the first step after ionization is the rapid formation of distinct H3O+ and OH units within the (H2O)n+ cluster. To explain the formation and survival of He(H2O)n+ clusters through to detection, the H3O+ is assumed to be located at the surface of the cluster with a dangling O–H bond to which a single helium atom can attach via a charge-induced dipole interaction. This study suggests that, like H+(H2O)n ions, the preferential location for the positive charge in large (H2O)n+ clusters is on the surface rather than as a solvated ion in the interior of the cluster.|
|Rights:||Copyright 2007 American Institute of Physics. Deposited with reference to the publisher's archiving policy available on the SHERPA/RoMEO website. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Chemical Physics, 2007, 127(13), 4303 and may be found at http://jcp.aip.org/resource/1/jcpsa6/v127/i13/p134303_s1.|
|Appears in Collections:||Published Articles, Dept. of Chemistry|
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