Change search
ReferencesLink to record
Permanent link

Direct link
A vibrational sum frequency spectroscopy study of the liquid-gas interface of acetic acid-water mixtures: 2: orientation analysis
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.ORCID iD: 0000-0002-9453-1333
Show others and affiliations
2005 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 1, 329-341 p.Article in journal (Refereed) Published
Abstract [en]

Vibrational sum frequency spectroscopy has been used to investigate the surface of aqueous acetic acid solutions. By studying the methyl and carbonyl vibrations with different polarization combinations, an orientation analysis of the acetic acid molecules has been performed in the concentration range 0-100%. The surface tension of acetic acid solutions was also measured in order to obtain the surface concentration. The orientation of the interfacial acetic acid molecules was found to remain essentially constant in an upright position with the methyl group directed toward the gas phase in the whole concentration range. The tilt angle (theta(CH3)) of the symmetry axis of the methyl group with respect to the surface normal was found to be lower than 15degrees when considering a delta distribution of angles or as narrow as 0 +/- 11degrees when assuming a Gaussian distribution. Further investigations showed that the C=O bond tilt (theta(C=O)) of the acetic acid hydrated monomer was constant and close to 55degrees in the concentration range where it was detected. Finally, the orientation information is discussed in terms of different species of acetic acid, where the formation of a surface layer of acetic acid cyclic dimers is proposed at high acid concentrations.

Place, publisher, year, edition, pages
2005. Vol. 109, no 1, 329-341 p.
Keyword [en]
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-7700DOI: 10.1021/jp047337yISI: 000226213200049ScopusID: 2-s2.0-12344308339OAI: diva2:12804
QC 20100825Available from: 2005-10-20 Created: 2005-10-20 Last updated: 2010-10-29Bibliographically approved
In thesis
1. Vibrational Sum Frequency and Infrared Reflection/Absorption Spectroscopy Studies of the Air/Liquid and Liquid/Metal Interfaces
Open this publication in new window or tab >>Vibrational Sum Frequency and Infrared Reflection/Absorption Spectroscopy Studies of the Air/Liquid and Liquid/Metal Interfaces
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Atmospheric corrosion, the most common form of metal corrosion, occurs within the interfacial region between a solid, and the surrounding atmosphere. In fact three phases and two interfaces are involved: the gas, a thin liquid layer, a solid, the gas/liquid and the liquid/solid interfaces. In this thesis, the vapor/liquid and liquid/metal interfaces have been studied by the in-situ techniques vibrational sum frequency spectroscopy (VSFS), and infrared reflection/absorption spectroscopy (IRAS). The main focus has been on characterization of the corrosive organic molecules formic acid, acetic acid, and acetaldehyde, at the two interfaces. Additionally, the headgroup of sodium dodecyl sulfate (SDS) has been examined at the air/water interface.

VSFS is an inherently surface sensitive laser spectroscopy technique, which provides vibrational spectra solely of the molecules residing at the surface of for example a liquid, despite the vast excess of the same molecules in the bulk. To obtain a comprehensive molecular picture of the organic compounds at the air/liquid interface, studies have been undertaken in several spectral regions, targeting the CH, C=O, C-O, OH, and SO3 stretching vibrations. Furthermore, the surrounding water molecules have been investigated in order to study hydration phenomena. Acetaldehyde has been determined to partly form a gem-diol (CH3CH(OH)2) at the air/water interface, whereas acetic acid forms various hydrogen-bonded species, with hydrated monomers at low concentrations and centrosymmetric cyclic dimers at high concentrations. Formic acid was found to form a different complex at very high concentrations, in addition to the species observed at low concentrations. Performing experiments with different polarizations of the laser beams has enabled the determination of the orientation of the interfacial molecules. The methyl group of acetic acid was concluded to be oriented close to the surface normal throughout the concentration range, whereas the tilt angle of the CH group of formic acid was determined to be ~35°. The SDS studies revealed that the headgroup orientation is constant in a wide range of concentrations, and also in the presence of sodium chloride.

IRAS has provided information regarding the composition and kinetics of the corrosion products formed upon exposure of a zinc oxide surface to the organic compounds. The importance of the water adlayer on metal surfaces has been confirmed by the faster kinetics observed at higher relative humidities. Exposure to formic acid resulted in the formation of zinc formate, whereas both acetic acid and acetaldehyde formed zinc acetate upon reaction with the zinc oxide surface. However, the kinetics were faster for acetic acid than acetaldehyde, which was explained in terms of an acetate-induced zinc dissolution process and a more complicated reaction path involved in the acetaldehyde case to form the zinc acetate surface species. Scanning electron microscopy indicated the formation of radially growing reaction products for acetic acid and filiform corrosion for acetaldehyde.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. vi, 57 p.
Corrosion science, laser spectroscopy, nonlinear optics
National Category
Materials Engineering
urn:nbn:se:kth:diva-455 (URN)91-7178-156-0 (ISBN)
Public defence
2005-10-28, M3, Brinellvägen 64, KTH, 10:00
QC 20101029Available from: 2005-10-20 Created: 2005-10-20 Last updated: 2011-03-18Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Tyrode, EricJohnson, MagnusLeygraf, ChristoferRutland, Mark
By organisation
Surface ChemistryCorrosion Science
In the same journal
Journal of Physical Chemistry B
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 84 hits
ReferencesLink to record
Permanent link

Direct link