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Vibrational Sum Frequency and Infrared Reflection/Absorption Spectroscopy Studies of the Air/Liquid and Liquid/Metal Interfaces
KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
2005 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH , 2005. , s. vi, 57
Nyckelord [en]
Corrosion science, laser spectroscopy, nonlinear optics
Nationell ämneskategori
Materialteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-455ISBN: 91-7178-156-0 (tryckt)OAI: oai:DiVA.org:kth-455DiVA, id: diva2:12811
Disputation
2005-10-28, M3, Brinellvägen 64, KTH, 10:00
Opponent
Handledare
Anmärkning
QC 20101029Tillgänglig från: 2005-10-20 Skapad: 2005-10-20 Senast uppdaterad: 2011-03-18Bibliografiskt granskad
Delarbeten
1. A vibrational sum frequency spectroscopy study of the liquid-gas interface of acetic acid-water mixtures: 1: surface speciation
Öppna denna publikation i ny flik eller fönster >>A vibrational sum frequency spectroscopy study of the liquid-gas interface of acetic acid-water mixtures: 1: surface speciation
Visa övriga...
2005 (Engelska)Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, nr 1, s. 321-328Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Aqueous acetic acid solutions have been studied by vibrational sum frequency spectroscopy (VSFS) in order to acquire molecular information about the liquid-gas interface. The concentration range 0-100% acetic acid has been studied in the CH/OH and the C-O/C=O regions, and in order to clarify peak assignments, experiments with deuterated acetic acid and water have also been performed. Throughout the whole concentration range, the acetic acid is proven to be protonated. It is explicitly shown that the structure of a water surface becomes disrupted even at small additions of acetic acid. Furthermore, the spectral evolution upon increasing the concentration of acetic acid is explained in terms of the different complexes of acetic acid molecules, such as the hydrated monomer, linear dimer, and cyclic dimer. In the C=O region, the hydrated monomer is concluded to give rise to the sum frequency (SF) signal, and in the CH region, the cyclic dimer contributes to the signal as well. The combination of results from the CH/OH and the C-O/C=O regions allows a thorough characterization of the behavior of the acetic acid molecules at the interface to be obtained.

Nyckelord
CH3COOH CH3COOD CD3COOH; AQUEOUS-SOLUTIONS; RAMAN-SPECTRA; AIR/WATER INTERFACE; CARBOXYLIC-ACIDS; IR-SPECTRA; AB-INITIO; GENERATION; MOLECULES; CORROSION
Nationell ämneskategori
Kemi
Identifikatorer
urn:nbn:se:kth:diva-7699 (URN)10.1021/jp047338q (DOI)000226213200048 ()2-s2.0-12344332758 (Scopus ID)
Anmärkning
QC 20100825Tillgänglig från: 2005-10-20 Skapad: 2005-10-20 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
2. A vibrational sum frequency spectroscopy study of the liquid-gas interface of acetic acid-water mixtures: 2: orientation analysis
Öppna denna publikation i ny flik eller fönster >>A vibrational sum frequency spectroscopy study of the liquid-gas interface of acetic acid-water mixtures: 2: orientation analysis
Visa övriga...
2005 (Engelska)Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, nr 1, s. 329-341Artikel i tidskrift (Refereegranskat) 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.

Nyckelord
MOLECULAR MECHANICS METHOD; CH3COOH CH3COOD CD3COOH; CH STRETCHING MODES; SPECTRES INFRAROUGES; GENERATION SPECTRUM; INTERNAL-ROTATION; CARBOXYLIC-ACIDS; BINARY-MIXTURES; RAMAN-SPECTRUM; SFG SPECTRUM
Nationell ämneskategori
Kemi
Identifikatorer
urn:nbn:se:kth:diva-7700 (URN)10.1021/jp047337y (DOI)000226213200049 ()2-s2.0-12344308339 (Scopus ID)
Anmärkning
QC 20100825Tillgänglig från: 2005-10-20 Skapad: 2005-10-20 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
3. Study of the adsorption of sodium dodecyl sulfate (SDS) at the air/water interface: targeting the sulfate headgroup using vibrational sum frequency spectroscopy
Öppna denna publikation i ny flik eller fönster >>Study of the adsorption of sodium dodecyl sulfate (SDS) at the air/water interface: targeting the sulfate headgroup using vibrational sum frequency spectroscopy
2005 (Engelska)Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 7, nr 13, s. 2635-2640Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The surface sensitive technique vibrational sum frequency spectroscopy (VSFS), has been used to study the adsorption behaviour of SDS to the liquid/vapour interface of aqueous solutions, specifically targeting the sulfate headgroup stretches. In the spectral region extending from 980 to 1850 cm(-1), only the vibrations due to the SO3 group were detectable. The fitted amplitudes for the symmetric SO3 stretch observed at 1070 cm(-1) for the polarization combinations ssp and ppp, were seen to follow the adsorption isotherm calculated from surface tension measurements. The orientation of the sulfate headgroup in the concentration range spanning from 1.0 mM to above the critical micellar concentration ( c. m. c.) was observed to remain constant within experimental error, with the pseudo-C-3 axis close to the surface normal. Furthermore, the effect of increasing amounts of sodium chloride at SDS concentrations above c. m. c. was also studied, showing an increase of approximately 12% in the fitted amplitude for the symmetric SO3 stretch when increasing the ionic strength from 0 to 300 mM NaCl. Interestingly, the orientation of the SDS headgroup was also observed to remain constant within this concentration range and identical to the case without NaCl.

Nyckelord
Adsorption, Air, Sodium Chloride, Sodium Dodecyl Sulfate, Spectrophotometry, Infrared, Surface Properties, Water
Nationell ämneskategori
Kemi
Identifikatorer
urn:nbn:se:kth:diva-24909 (URN)10.1039/b505219j (DOI)000229978300014 ()2-s2.0-22244490701 (Scopus ID)
Anmärkning
QC 20100930Tillgänglig från: 2010-09-30 Skapad: 2010-09-30 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
4. Infrared spectroscopy
Öppna denna publikation i ny flik eller fönster >>Infrared spectroscopy
2006 (Engelska)Ingår i: Analytical Methods In Corrosion Science and Engineering, Boca Raton: CRC Press , 2006Kapitel i bok, del av antologi (Övrigt vetenskapligt)
Ort, förlag, år, upplaga, sidor
Boca Raton: CRC Press, 2006
Nationell ämneskategori
Materialteknik
Identifikatorer
urn:nbn:se:kth:diva-7702 (URN)
Anmärkning
QC 20101029Tillgänglig från: 2005-10-20 Skapad: 2005-10-20 Senast uppdaterad: 2010-10-29Bibliografiskt granskad
5. Atmospheric corrosion of zinc by organic constituents I. The role of the zinc/water and water/air interfaces studied by infrared reflection/absorption spectroscopy and vibrational sum frequency spectroscopy
Öppna denna publikation i ny flik eller fönster >>Atmospheric corrosion of zinc by organic constituents I. The role of the zinc/water and water/air interfaces studied by infrared reflection/absorption spectroscopy and vibrational sum frequency spectroscopy
2006 (Engelska)Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 3, s. B113-B120Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The zinc oxide/water and water/air interfaces have been investigated in order to elucidate the role of these two interfaces in an atmospheric corrosion process. Vibrational sum frequency spectroscopy (VSFS) has been used to study the water/air interface of aqueous acetic acid and acetaldehyde solutions. The VSFS studies revealed that the interfacial region of the acetic acid solutions is dominated by various species formed by hydrogen bonding, whereas acetaldehyde underwent a hydration process to form a gem-diol. In both cases, even small additions resulted in a breakdown of the surface structure found in pure water. Infrared reflection/absorption spectroscopy (IRAS) has been utilized to examine the zinc oxide/ water interface upon exposure of gaseous acetic acid and acetaldehyde at various relative humidities. The in situ IRAS investigations indicated a formation of zinc acetate both when the zinc oxide surface was exposed to acetic acid and acetaldehyde. Thus, despite being different in nature, these compounds resulted in the same end product in the corrosion process studied.

Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:kth:diva-24287 (URN)10.1149/1.2164788 (DOI)000235136600037 ()2-s2.0-32044475342 (Scopus ID)
Anmärkning
QC 20100831. Tidigare titel: Atmospheric corrosion of zinc by organic constituents: 1. The role of the zinc/water and water/air interfaces studied by IRAS and VSFSTillgänglig från: 2010-08-31 Skapad: 2010-08-31 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
6. Atmospheric corrosion of zinc by organic constituents II. Reaction routes for zinc-acetate formation
Öppna denna publikation i ny flik eller fönster >>Atmospheric corrosion of zinc by organic constituents II. Reaction routes for zinc-acetate formation
2006 (Engelska)Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 12, s. B542-B546Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The acetic acid and acetaldehyde-induced atmospheric corrosion of a zinc surface was investigated by in situ infrared reflection-absorption spectroscopy. Independent of the relative humidity, both corrosive gases yielded zinc oxide and zinc acetate as reaction products. However, faster kinetics for the acetate formation was observed for acetic acid, which was attributed to an acetate-induced zinc dissolution mechanism as the rate determining step, and a more complicated reaction path for acetaldehyde to form the zinc-acetate surface species. Additionally, the rate varied significantly with the relative humidity, and an enhanced corrosion rate was observed under more humid conditions, when the water adlayer that always covers a metal surface is thicker. Scanning electron microscopy revealed the formation of radial growth of corrosion products in the case of acetic acid and filiform corrosion for acetaldehyde. By X-ray diffraction of the powderlike corrosion products, solely zinc oxide was detected. This implies a minute production of zinc acetate in comparison to zinc oxide, or a noncrystalline phase of the acetate. Reaction paths for acetic acid and acetaldehyde were proposed.

Nyckelord
Acetic acid, Atmospheric humidity, Dissolution, Reaction kinetics, Surface reactions, Zinc
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:kth:diva-24288 (URN)10.1149/1.2360740 (DOI)000241757400032 ()2-s2.0-33750810816 (Scopus ID)
Anmärkning
QC 20100831Tillgänglig från: 2010-08-31 Skapad: 2010-08-31 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
7. A vibrational sum frequency spectroscopy study of the liquid/vapor interface of formic acid/water solutions
Öppna denna publikation i ny flik eller fönster >>A vibrational sum frequency spectroscopy study of the liquid/vapor interface of formic acid/water solutions
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Nationell ämneskategori
Materialteknik
Identifikatorer
urn:nbn:se:kth:diva-25768 (URN)
Anmärkning
QC 20101029Tillgänglig från: 2010-10-29 Skapad: 2010-10-29 Senast uppdaterad: 2010-10-29Bibliografiskt granskad
8. Atmospheric corrosion of zinc by organic constituents - III. An infrared reflection-absorption spectroscopy study of the influence of formic acid
Öppna denna publikation i ny flik eller fönster >>Atmospheric corrosion of zinc by organic constituents - III. An infrared reflection-absorption spectroscopy study of the influence of formic acid
2006 (Engelska)Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 12, s. B547-B550Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The initial corrosion of a zinc surface exposed to formic acid at various relative humidities has been investigated by in situ infrared reflection-absorption spectroscopy. The major corrosion product observed was zinc formate, as evidenced in particular by the two strong carboxylate stretching vibrations. The importance of the thickness of the water adlayer always covering a metal surface was confirmed by the more rapid corrosion process monitored at higher relative humidities. Nonetheless, significant corrosion rates were observed even at low (25%) relative humidities. The corrosion rate at a given humidity was observed to initially be very fast, followed by slower kinetics at longer exposure times. This indicates a protective ability of the corrosion products formed compared to the initially more reactive fresh zinc surface.

Nyckelord
Atmospheric humidity, Corrosion protection, Molecular vibrations, Organic acids, Reaction kinetics, Surface reactions, Zinc
Nationell ämneskategori
Teknik och teknologier
Identifikatorer
urn:nbn:se:kth:diva-24286 (URN)10.1149/1.2360741 (DOI)000241757400033 ()2-s2.0-33750820117 (Scopus ID)
Anmärkning
QC 20100831. Tidigare titel: Atmospheric corrosion of zinc by organic constituents: 3. An IRAS study of the influence of formic acidTillgänglig från: 2010-08-31 Skapad: 2010-08-31 Senast uppdaterad: 2017-12-12Bibliografiskt granskad

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