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Alcohols at the aqueous surface: chain length and isomer effects

Walz, Marie-Madeleine and Werner, Josephina and Ekholm, Victor and Prisle, Nønne and Öhrwall, Gunnar and Björneholm, Olle (2016). Alcohols at the aqueous surface: chain length and isomer effects. Physical Chemistry Chemical Physics. 18:9, 6648-6656
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Official URL: http://dx.doi.org10.1039/C5CP06463E

Abstract

Surface-active organic molecules at the liquid-vapor interface are of great importance in atmospheric science. Therefore, we studied the surface behavior of alcohol isomers with different chain lengths (C4-C6) in aqueous solution with surface-and chemically sensitive X-ray photoelectron spectroscopy (XPS), which reveals information about the surface structure on a molecular level. Gibbs free energies of adsorption and surface concentrations are determined from the XPS results using a standard Langmuir adsorption isotherm model. The free energies of adsorption, ranging from around -15 to -19 kJ mol(-1) (C4-C6), scale linearly with the number of carbon atoms within the alcohols with Delta G(Ads) per-CH2-approximate to -2 kJ mol(-1.) While for the linear alcohols, surface concentrations lie around 2.4 x 10(14) molecules per cm(2) at the bulk concentrations where monolayers are formed, the studied branched alcohols show lower surface concentrations of around 1.6 x 10(14) molecules per cm(2), both of which are in line with the molecular structure and their orientation at the interface. Interestingly, we find that there is a maximum in the surface enrichment factor for linear alcohols at low concentrations, which is not observed for the shorter branched alcohols. This is interpreted in terms of a cooperative effect, which we suggest to be the result of more effective van der Waals interactions between the linear alcohol alkyl chains at the aqueous surface, making it energetically even more favorable to reside at the liquid-vapor interface.

Authors/Creators:Walz, Marie-Madeleine and Werner, Josephina and Ekholm, Victor and Prisle, Nønne and Öhrwall, Gunnar and Björneholm, Olle
Title:Alcohols at the aqueous surface: chain length and isomer effects
Series/Journal:Physical Chemistry Chemical Physics (1463-9084)
Year of publishing :2016
Volume:18
Number:9
Page range:6648-6656
Number of Pages:9
Publisher:Royal Society of Chemistry
ISSN:1463-9084
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Accepted version
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X50 Chemistry
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 103 Physical Sciences > Atom and Molecular Physics and Optics
(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Organic Chemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Physical Chemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Inorganic Chemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Meteorology and Atmospheric Sciences
Agrovoc terms:alcohols, surfactants, atmospheric chemistry
Keywords:alcohols, surfactants, atmospheric chemistry
URN:NBN:urn:nbn:se:slu:epsilon-e-3727
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3727
Additional ID:
Type of IDID
Web of Science (WoS)000371139400030
DOIUNSPECIFIED
ID Code:13544
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Chemistry and Biotechnology (140101-161231)
Deposited By: SLUpub Connector
Deposited On:10 Oct 2016 08:01
Metadata Last Modified:12 Feb 2017 00:15

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