| 1. |
- Baia, L., et al.
(författare)
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TiO2/WO3/Au nanoarchitectures' photocatalytic activity "from degradation intermediates to catalysts' structural peculiarities" Part II: Aerogel based composites - fine details by spectroscopic means
- 2014
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373. ; 148, s. 589-600
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Tidskriftsartikel (refereegranskat)abstract
- The "build-up" methodology of a composite photocatalyst is a critical issue regarding the showed photocatalytic performance, including the formation of intermediates. To investigate this issue TiO2/WO3/Au aerogel composites were obtained by sal-gel method and subsequent photoreduction (Au) with UV or visible light. The obtained composites' photocatalytic activity and intermediate formation profiles were evaluated using phenol as a model pollutant. XPS/UPS, XAFS and DRS were used to uncover local coordination, surface chemistry (of the different types of atoms (Ti, W, O and Au) and the band-structure (band-gap, possible electron transitions) of the obtained nanomaterials. The intermediates' evolution profile and structural peculiarities were successfully correlated and it was shown that each minor structural (bulk or surface) change has a significant impact on the photocatalytic activity and intermediate formation dynamics. (c) 2013 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Csendes, Z., et al.
(författare)
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Superoxide dismutase inspired Fe(III)-amino acid complexes covalently grafted onto chloropropylated silica gel - Syntheses, structural characterisation and catalytic activity
- 2013
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860. ; 1044, s. 39-45
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Tidskriftsartikel (refereegranskat)abstract
- In this work the syntheses, structure and SOD activity of covalently grafted Fe(III)-complexes formed with various N- or C-protected amino acid ligands (L-histidine and L-tyrosine) inspired by the active site of the Fe SOD enzyme are presented. Chloropropylated silica gel was used as support to mimic the proteomic skeleton of the enzyme. Anchored complexes having uniform amino acids as well as their two-component mixtures have been prepared. The products were characterised by mid and far IR and Raman spectroscopies. SOD activities of the substances were determined via the Beauchamp-Fridovich test reaction. It was found that the preparation of covalently anchored Fe(III)-amino acid complexes was successful in many cases. The structures of the anchored complexes and the coordinating groups varied upon changing the conditions of the syntheses. All the covalently immobilised complexes displayed (in some instances appreciable) SOD activity. (C) 2012 Elsevier B.V. All rights reserved.
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| 4. |
- Haldrup, K., et al.
(författare)
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Guest-Host Interactions Investigated by Time-Resolved X-ray Spectroscopies and Scattering at MHz Rates: Solvation Dynamics and Photoinduced Spin Transition in Aqueous Fe(bipy)(3)(2+)
- 2012
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Ingår i: The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory. - : American Chemical Society (ACS). - 1520-5215. ; 116:40, s. 9878-9887
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the photoinduced low spin (LS) to high spin (HS) conversion of [Fe(bipy)(3)](2+) in aqueous solution. In a laser pump/X-ray probe synchrotron setup permitting simultaneous, time-resolved X-ray diffuse scattering (XDS) and X-ray spectroscopic measurements at a 3.26 MHz repetition rate, we observed the interplay between intramolecular dynamics and the intermolecular caging solvent response with better than 100 ps time resolution. On this time scale, the initial ultrafast spin transition and the associated intramolecular geometric structure changes are long completed, as is the solvent heating due to the initial energy dissipation from the excited HS molecule. Combining information from X-ray emission spectroscopy and scattering, the excitation fraction as well as the temperature and density changes of the solvent can be closely followed on the subnanosecond time scale of the HS lifetime, allowing the detection of an ultrafast change in bulk solvent density. An analysis approach directly utilizing the spectroscopic data in the XDS analysis effectively reduces the number of free parameters, and both combined permit extraction of information about the ultrafast structural dynamics of the caging solvent, in particular, a decrease in the number of water molecules in the first solvation shell is inferred, as predicted by recent theoretical work.
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| 5. |
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| 6. |
- Sranko, D., et al.
(författare)
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A SEM, EDX and XAS characterization of Ba(II)Fe(III) layered double hydroxides
- 2011
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860. ; 993:1-3, s. 62-66
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Konferensbidrag (refereegranskat)abstract
- The structural characteristics of Ba-Fe double hydroxides were studied by various methods, such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX) fluorescence and X-ray absorption spectroscopies (XAS). It was verified that under hyperalkaline conditions (using 10 M or 20 M NaOH solution for precipitating the substances) layered double hydroxides could be prepared and the structure collapsed on heat treatment at 523 K. Important structural parameters could also be obtained through the quantitative analysis of the XAS spectrum of Ba3Fe-LDH made using 20 M NaOH for precipitating the material. (C) 2010 Elsevier B.V. All rights reserved.
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