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- Klug, Otto, et al.
(författare)
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A novel method for investigation of dibasic aromatic acids on oxidized aluminium surfaces by NIR-FT-SERS
- 1997
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Ingår i: Progress in Fourier Transform Spectroscopy. - Vienna : Springer Vienna. ; , s. 649-651
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Konferensbidrag (refereegranskat)abstract
- A new technique is presented for detecting dibasic aromatic acids on an SERS-inactive oxidized aluminium foil by utilizing near-infrared Fourier-transform surface-enhanced Raman spectroscopy (NIR-FT-SERS). Identification of adsorbed ortho-, meta- and para-phthalic acids on a typical anodic foil of electrolytic capacitors From electrolytes containing 1 ppm substrate was successfully accomplished.
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| 2. |
- Klug, Otto, et al.
(författare)
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A Spectroscopic Study of Phthalate Adsorption on γ-Aluminum Oxide
- 1999
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 15:20, s. 6961-6968
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Tidskriftsartikel (refereegranskat)abstract
- Surface complexation of phthalic acid/phthalate has been investigated on synthetically produced, nonaged γ-aluminum oxide by infrared and Raman spectroscopy. Effects of time, pH, and ionic strength have been studied both on the total adsorbed amount of phthalate and on the surface complexes. The spectroscopic results indicated the formation of two different types of complexes: outer sphere and inner sphere. The relative concentrations of these complexes were shown to vary considerably with pH but very little with increasing ionic strength, which equally reduced the amount of both types of complexes. Considering the electrostatic interaction between the surface and adsorbate, a complexation model was proposed that is in accordance with the spectroscopic results. Adsorption on the synthetic γ-alumina was compared to the adsorption on γ-aluminum oxide films produced by anodic oxidation, where the adsorbed amount was greatly reduced; however, both inner- and outer-sphere types of complexation have been observed.
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| 3. |
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| 4. |
- Klug, Ottó
(författare)
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Phthalate adsorption on gamma-alumina: a spectroscopic study
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adsorption of phthalic acid/phthalate has been investigated on anodically oxidized aluminium foils - used in wet electrolytic capacitors -, by different spectroscopic methods like UV, infrared, Raman and surface- enhanced Raman spectroscopy. In addition to the capacitor foils the adsorption was studied utilizing a high surface area, synthetic Y-aluminium oxide powder as a model material. The capacitor foils were first characterized comprising BET, SIMS, XRF and electron microscopic (SEM) measurements in order to determine the composition and structure of the oxide surface. Adsorption on the two different substrates has been compared and concluded to lead to the same type of surface complexes approving the applicability of the model material for further adsorption studies. In the adsorption experiments, the influence of time, pH and ionic media on the adsorbed amount, as well as on the structure of the surface complex has been studied. Based on the analyses of the different spectra the following conclusions can be drawn: The adsorption is a fast process driven by electrostatic forces. Complexation of the aromatic compound starts with either inner- or outer sphere co-ordination of the hydrogen phthalate ion. The ratio of the two types of complexes shows pH dependence which can be correlated to the different type of surface sites preferred at different pHs. Surface-enhanced Raman spectroscopy (SERS) was applied directly on the capacitor foils for detecting the adsorbed species. Besides of the analytical aspects of the method, a detailed investigation has been performed to explore of the mechanism of the SER effect in this particular experimental approach. It was concluded that SER spectra originate from a silver-phthalate complex rather than from the phthalate adsorbed on the oxide. The structure and orientation of the final SER species is discussed. Although the aluminium oxide surface of the capacitor foil is not involved in the SER complex, the roughness of the surface, and other properties of the substrate can have positive contribution to the enhancement.
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| 5. |
- Klug, Otto, et al.
(författare)
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Raman spectroscopy of aromatic acids adsorbed on oxidised aluminium foil
- 1997
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Ingår i: Journal of Molecular Structure. - 0022-2860 .- 1872-8014. ; 410, s. 183-188
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of ortho- and para-phthalic acids on oxidised aluminium foil was investigated by Raman and surface-enhanced Raman spectroscopy (SERS). Without any treatment of the foil only a modified method of SERS provided spectroscopic evidence of the adsorption. However, by dissolving the metal aluminium from the Al2O3-Al-Al2O3 structure of the foil, the adsorption could be investigated by Raman spectroscopy without surface-enhanced conditions. The vibrational bands of the adsorbed species, obtained by both types of Raman spectroscopy, are compared to the solid-state spectra of the pure acids and their dipotassium salts. The band shifts suggest that the adsorbed species are essentially in the carboxylate form; however, the Raman and the SER spectra of the same species are not identical indicating a separate chemical reaction occurring at the surface upon depositing the sol. (C) 1997 Elsevier Science B.V.
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