Encyclopedia of Analytical Chemistry

Meyers, Robert A.

doi:10.1002/9780470027318

Cited by 330 publications

(26 citation statements)

References 5 publications

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“…However, these bands are obscured by relatively strong negative δHOH at 1638 cm -1 which are very similar to those obtained by other workers [13], [14]. The bands at 1045 cm -1 have previously been assigned in the literature to rocking CH3 vibrations [15], [16] whereas the bands at 925-975 and 900 cm -1 can be assigned, respectively to C-C and OH bending [11], [17], [12].…”

Section: Atr-ftir Studysupporting

confidence: 87%

Pathways of the photocatalytic reaction of acetate in H2O and D2O: A combined EPR and ATR-FTIR study

Belhadj

Melchers

Robertson

et al. 2016

Journal of Catalysis

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The adsorption and photocatalytic degradation of acetate on TiO2 surfaces was investigated in H2O and D2O by ATR-FTIR and EPR Spectroscopy respectively. These studies were carried out in the dark and under UV(A) illumination to gain additional insights into the adsorption behaviour with the identification of paramagnetic species formed during the oxidation of acetate. Isotopic exchange during the adsorption of D2O on TiO2 surface led to different interactions between the adsorbate and OD groups. At different pH levels, several surface complexes of acetate can be formed such as monodentate, or bidentates. Under UV(A) irradiation of TiO2 aqueous suspensions, the formation of hydroxyl and methoxy radicals evidenced as the corresponding spin-adducts, were found to dominate in alkaline and acidic suspensions respectively. Two possible pathways for the oxidation of acetate have been suggested at different pH levels in solution in terms of the source of the spin adduct formed.These proposed pathways were found to be in good agreement with ATR-FTIR and EPR results.

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Section: Atr-ftir Studysupporting

confidence: 87%

Pathways of the photocatalytic reaction of acetate in H2O and D2O: A combined EPR and ATR-FTIR study

Belhadj

Melchers

Robertson

et al. 2016

Journal of Catalysis

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“…135 Inverse photoemission spectrometry (STM-LE) derives advantage from the inverse photo effect by detecting the light emission caused by tunneling electrons. 15,87,116,123 STM-LE is comparable to cathodoluminescence imaging in SEM. The quantum yield is much lower, about 10 4 photons per tunneling electron, and most of the tunneling electrons only heat the sample.…”

Section: Microwaves and Lightmentioning

confidence: 62%

“…50 In SNOM, nonradiative electromagnetic near-field interaction serves for imaging. 116,117 These interactions have a decay length shorter than the wavelength. Therefore, the diffraction limit of optical microscopy (see Equation 8, section 2.6) does not hold.…”

Section: Microwaves and Lightmentioning

confidence: 99%

“…Any inhomogeneity in a radiation field becomes a source of radiation, an antenna, whose dielectric and magnetic near-field properties can be characterized with the help of its far field. 116 The antenna can be used as a transmitter and receiver or only as a receiver. Investigations can be conducted in transmission or in reflection.…”

Section: Microwaves and Lightmentioning

confidence: 99%

“…Another way of producing a small aperture is a metallic coating with a tiny hole on a glass fiber or a glass slide. 116,117,121 In contrast to AFM, SNOM is not sensitive to electrical charges. 131 As in all near-field interactions, the optical near-field signals are strongly dependent on the distance.…”

Section: Microwaves and Lightmentioning

confidence: 99%

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Microscopy of Coatings

Rädlein¹

2000

Encyclopedia of Analytical Chemistry

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Fundamental research on films and the development and optimization of coatings are not possible without high‐resolution imaging. This article describes the advantages and disadvantages of the newly introduced scanning probe microscopy (SPM) in comparison with well‐established microscopy techniques with light and particles [e.g. scanning electron microscopy (SEM) and transmission electron microscopy (TEM)], which are limited by the diffraction limit, i.e. 200 nm for conventional light microscopy and 4 nm for SEM. This limit does not hold for SPM, which uses near‐field interactions for imaging. Thus, even simple atoms or molecules can be resolved on well‐ordered structures by scanning tunneling microscopy (STM) or atomic force microscopy (AFM). Both possess an extremely good height sensitivity of 0.02 nm. 1 In the constant‐height operation mode, AFM can detect vertical forces as low as 10 −15 –10 −4 N. Atomic resolution is not always possible or not always necessary for many practical applications; a lateral resolution of a few nanometers is sufficient. Besides the capability of achieving this value with ease, simple sample preparation, versatile environmental conditions and observation of reactions in situ are advantages of STM and AFM. Especially AFM has proved to be a useful technique for investigating coatings, because it is independent of conductivity and provides topographic data together with information on structure, local variations of mechanical properties and surface alterations in different media. However, some artifacts and restrictions have to be considered which can differ considerably from customary electron micrographs with comparable resolutions, such as onset overswing and tip convolution. Microscopy helps in solving coating problems according to substrate quality, nucleation, wettability, thickness, roughness, microstructure, crystal phases (texture, orientation), lateral and vertical homogeneity, density, porosity, interfaces, adhesion, hardness, stress, scratch and abrasion resistance, tribology, wear and corrosion. Practical examples of microscopy results on these questions are presented together with suitable preparation methods and interpretation of artifacts.

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Effects of thermal stressing on saturated vegetable oils and isolated triacylglycerols - product analysis by MALDI-TOF mass spectrometry, NMR and IR spectroscopy

Schiller

Süß

Petković

et al. 2002

Eur. J. Lipid Sci. Technol.

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It is well‐known that triacylglycerols in vegetable oils undergo slow oxidative modifications upon storage particularly at elevated temperatures. This has been shown primarily for oils with unsaturated fatty acid residues that are most sensitive towards oxidation. Saturated oils, however, were by far less investigated. In the present study saturated oils (coconut oil) as well as isolated triacylglycerols were exposed to defined thermal stressing and the resulting products were investigated in dependence on temperature and the heating period. Matrix‐assisted laser desorption and ionization spectrometry, 13C and 31P nuclear magnetic resonance spectroscopy and infrared spectroscopy were used for the characterization of the native as well as the thermally stressed oil samples. These methods were used since they provide both, fast and reliable information on oil composition and can be performed faster than other more established methods. We found that the degradation mechanism of saturated fatty acids is completely different from unsaturated fatty acids. Whereas unsaturated oils are primarily depleted under the cleavage of the double bonds, saturated oils undergo a conversion of one methylene group into a carbonyl group. This was independently demonstrated by all applied methods for the triacylglycerols as well as for the free fatty acids derived after saponification.

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Encyclopedia of Analytical Chemistry

Cited by 330 publications

References 5 publications

Pathways of the photocatalytic reaction of acetate in H2O and D2O: A combined EPR and ATR-FTIR study

Pathways of the photocatalytic reaction of acetate in H2O and D2O: A combined EPR and ATR-FTIR study

Microscopy of Coatings

Effects of thermal stressing on saturated vegetable oils and isolated triacylglycerols - product analysis by MALDI-TOF mass spectrometry, NMR and IR spectroscopy

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