| 1. |
- Shah, Faiz Ullah, 1981-, et al.
(författare)
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Interfacial Behavior of Orthoborate Ionic Liquids at Inorganic Oxide Surfaces Probed by NMR, IR, and Raman Spectroscopy
- 2018
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:34, s. 19687-19698
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Tidskriftsartikel (refereegranskat)abstract
- Absorption modes and the reactivity of nonhalogenated ionic liquids (ILs) at inorganic oxide surfaces of γ-Al2O3, MgO, and SiO2 particles were characterized using multinuclear (11B, 31P, and 29Si) solid-state magic-angle-spinning NMR, FTIR, and Raman spectroscopy. ILs are composed of the trihexyl(tetradecyl)phosphonium cation, [P6,6,6,14]+, and bis(mandelato)borate, [BMB]-, or bis(salicylato)borate, [BScB]-, anions. Spectroscopic measurements were performed on room-temperature (298 K) samples and samples exposed to 15 h at 373 K. The single-pulse 11B NMR data of heated [P6,6,6,14][BMB] mixed with the inorganic oxides showed a significant change in the spectra of the anion for all three oxides. In contrast, no such spectral changes were detected for heated [P6,6,6,14][BScB] mixed with the inorganic oxides. 31P MAS NMR data for the IL/metal oxide systems revealed interactions between [P6,6,6,14]+ and the surfaces of oxides. A significant intensity of 31P CP-MAS NMR signals indicated a low mobility of cations in these systems. The existence of strongly adhered surface layers of ILs on SiO2 particles was also confirmed by 1H-29Si CP-MAS NMR spectroscopy. FTIR and Raman spectroscopic data revealed strong interactions between the anions and the inorganic surfaces, and there is a strong correlation with the data obtained from NMR spectroscopy. Although their chemical structures are rather similar, the [BScB]- anion is more stable than the [BMB]- anion at the inorganic oxide surfaces.
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| 3. |
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| 4. |
- Beattie, D.A., et al.
(författare)
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In situ total internal reflection Raman spectroscopy of surfactant adsorption at a mineral surface
- 2006
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Ingår i: Vibrational Spectroscopy. - : Elsevier BV. - 0924-2031 .- 1873-3697. ; 41:2, s. 198-204
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Tidskriftsartikel (refereegranskat)abstract
- We present the first attempt to characterise surfactant adsorption from solution onto a particle film using total internal reflection Raman spectroscopy. Three surfactant collectors of interest to the mineral processing industry were studied in their adsorption onto sphalerite: heptyl xanthate, 2-mercaptobenzothiazole (MBT), and O,O-dibutyldithiophosphate (DTP). All three surfactants adsorbed to the surface of the sphalerite. Adsorption of heptyl xanthate was monitored as a function of time and increasing concentration. The spectrum of heptyl xanthate indicated the presence of a small amount of dixanthogen on the surface of the sphalerite. MBT adsorption studies were complicated due to the fluorescence of the adsorbed layer. However, peaks due to the adsorbed MBT were observed on top of the fluorescent background, allowing the identification of the adsorbed species to be confirmed as the oxidised dimer species. Spectra obtained from MBT and DTP co-adsorption studies did not display the strong adsorbate layer fluorescence, indicating that the fluorescence spectrum of the adsorbed MBT is most likely affected by ring-ring interactions.
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| 5. |
- Billes, Ferenc, et al.
(författare)
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A combined DFT and vibrational spectroscopy study of the nickel and zinc O,O-diethyldithiophosphate complexes
- 2010
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Ingår i: Vibrational Spectroscopy. - : Elsevier BV. - 0924-2031 .- 1873-3697. ; 53:2, s. 296-306
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Tidskriftsartikel (refereegranskat)abstract
- Based on our earlier results on the theoretical and experimental study of potassium O,O-diethyldithiophosphate, the normal modes of nickel and zinc O,O-diethyldithiophoshate complexes were elucidated. Infrared and Raman spectra of these compounds were recorded. Quantum chemical calculations resulted in optimized structures, electric charge distributions, vibrational force constants, and fundamental frequencies. Normal coordinate analysis was applied to characterize the vibrational modes. Based on the results of these calculations vibrational spectra were simulated. The largest spectral differences between the two complexes appeared in vibrational modes encompassing the central part of the formula unit viz. PS2MS2P, where M is the metal atom. Namely, this central part of the Ni complex has D2h symmetry, while that of the Zn one has D2d symmetry.
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| 6. |
- Billes, Ferenc, et al.
(författare)
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Molecular geometry and vibrational spectroscopy of potassium O,O-diethyldithiophosphate
- 2006
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Ingår i: Vibrational Spectroscopy. - : Elsevier BV. - 0924-2031 .- 1873-3697. ; 40:1, s. 89-97
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to build a good theoretical and experimental basis for the further study of changes in structure and spectra of the O,O-diethyldithiophosphate anion upon its adsorption on the surfaces of transition metal sulfides.Infrared and Raman spectra of potassium O,O-diethyldithiophosphate were recorded. High level quantum chemical calculations were carried out to optimize the molecular geometry of both the potassium salt and its anion. Vibrational force constants were calculated from the second derivative of the molecular energy function with respect to the Cartesian coordinates of the atoms. With the aid of the optimized geometry and the calculated vibrational force constants a normal coordinate analysis was carried out to characterize the molecular vibrational modes and to assign the vibrational frequencies.
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| 7. |
- Billes, Ferenc, et al.
(författare)
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Vibrational spectroscopic and conformational analysis of pinosylvin
- 2002
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 106:26, s. 6232-6241
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Tidskriftsartikel (refereegranskat)abstract
- Infrared and Raman spectra of pinosylvin were recorded and the vibrational frequencies with the corresponding infrared intensities were compared with the results of ab initio calculations utilizing the DFT method with the Becke3P86 functional and the 6-31G(d) basis set. Normal coordinate analysis was carried out. The effect of the conformation of the OH groups on the distribution of net charges, molecular energy and vibrational fundamentals were analyzed. One of the OH-cis-OH-trans conformers has the lowest energy. The conformation has a strong effect on the aforementioned properties, e.g., the cis-to-trans transition generates electron repulsion toward the vinylidene group between the two benzene rings. The changes in the different properties are in good accordance with each other. For comparison, the vibrational spectra were also recorded and calculated for the parent compound, trans-stilbene.
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| 8. |
- Bo, Qi-Bing, et al.
(författare)
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Simple directed material design through in situ substitution of proton with Cu+ ions
- 2009
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Ingår i: Journal of Inorganic and Organometallic Polymers and Materials. - : Springer Science and Business Media LLC. - 1574-1443 .- 1574-1451. ; 19:4, s. 485-493
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Tidskriftsartikel (refereegranskat)abstract
- A new inorganic-organic hybrid material (C10H8N2H)2(Mo8O26) · 2NH4 (1) was prepared under solvothermal conditions (H2O/ethanol), which was then used as a starting material in the synthesis of another material, (C10H8N2Cu)2(Mo8O26) · 2NH4 (2). Each compound has been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis, thermogravimetric analysis, fluorescence, FT-IR, and bond valence sum calculations. The comparative study focuses on the transformation and structural change between 1 and 2, which arises from the simple substitution of the proton in 1 with the Cu+ ions. The other surprising feature is that Cu+ ions can not only directly be used to substitute the proton of 1 but also ameliorate its photoluminescence property. It means that 1 appears to have recognizable functional protons in the solid-state structure and, hence, can very well be considered as an ideal precursor agent to design the functional materials with special architectures and photoactive properties.
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| 10. |
- Carabante, Ivan, et al.
(författare)
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Adsorption of As (V) on iron oxide nanoparticle films studied by in situ ATR-FTIR spectroscopy
- 2009
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Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 346:1-3, s. 106-113
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Tidskriftsartikel (refereegranskat)abstract
- Stabilization of arsenic contaminated soils by iron oxides has been proposed as a remediation technique to prevent leaching of arsenate into the environment. Fundamental studies are needed to establish under which conditions the complexes formed are stable. In the present work, a powerful technique, viz. ATR-FTIR spectroscopy, is adapted to studies of adsorption of arsenate species on iron oxides. This technique facilitates acquisition of both quantitative and qualitative in situ adsorption data.In the present work, about 800 nm thick films of 6-lineferrihydrite were deposited on ZnSe ATR crystals. Arsenate adsorption on the ferrihydrite film was studied at pD values ranging from 4 to 12 and at an arsenate concentration of 0.03 mM in D2O solution. The amount of adsorbed arsenate decreased with increasing pD as a result of the more negatively charged iron oxide surface at higher pD values. The adsorption and desorption kinetics were also studied. Arsenate showed a higher adsorption rate within the first 70 minutes and a much lower adsorption rate from 70 up to 300 minutes. The low adsorption rate at longer reaction times was partly due to a low desorption rate of already adsorbed carbonate species adsorbed at the surface. The desorption of carbonate species was evidenced by the appearance of negative absorption bands. The desorption of adsorbed arsenate complexes was examined by flushing with D2O at pD 4 and 8.5 and it was found that the complexes were very stable at pD 4 suggesting formation of mostly inner-sphere complexes whereas a fraction of the complexes at pD 8.5 were less stable than at pD 4, possibly due to the formation of outer-sphere complexes.In summary, the ATR technique was shown to provide in situ information about the adsorption rate, desorption rate and the speciation of the complexes formed within a single experiment, which is very difficult to obtain using other techniques.
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