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rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
2010-4-8
pubmed:abstractText
The reactivity of photolytically generated, gas-phase, ground-state atomic oxygen, O((3)P), with the surfaces of a series of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([NTf(2)]) ionic liquids has been investigated. The liquids differ only in the length of the linear C(n)H(2n+1) alkyl side chain on the cation, with n = 2, 4, 5, 8, and 12. Laser-induced fluorescence was used to detect gas-phase OH v' = 0 radicals formed at the gas-liquid interface. The reactivity of the ionic liquids increases nonlinearly with n, in a way that cannot simply be explained by stoichiometry. We infer that the alkyl chains must be preferentially exposed at the interface to a degree that is dependent on chain length. A relatively sharp onset of surface segregation is apparent in the region of n = 4. The surface specificity of the method is confirmed through the nonthermal characteristics of both the translational and rotational distributions of the OH v' = 0. These reveal that the dynamics are dominated by a direct, impulsive scattering mechanism at the outer layers of the liquid. The OH v' = 0 yield is effectively independent of the bulk temperature of the longest-chain ionic liquid in the range 298-343 K, also consistent with a predominantly direct mechanism. These product attributes are broadly similar to those of the benchmark pure hydrocarbon liquid, squalane, but a more detailed analysis suggests that the interface may be microscopically smoother for the ionic liquids.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Apr
pubmed:issn
1520-5215
pubmed:author
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
114
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4896-904
pubmed:year
2010
pubmed:articleTitle
O(3P) atoms as a chemical probe of surface ordering in ionic liquids.
pubmed:affiliation
School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
pubmed:publicationType
Journal Article