| 1. |
- Edwards, Marten O. M., et al.
(författare)
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Increased photoelectron transmission in High-pressure photoelectron spectrometers using "swift acceleration"
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 785, s. 191-196
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Tidskriftsartikel (refereegranskat)abstract
- A new operation mode of a HPXPS (high-pressure X-ray photoelectron spectroscopy) analyzer is evaluated on a HPXPS system fitted with an Al K alpha X-ray source. A variety of metal foil samples (gold, silver and copper) were measured in different sample gas environments (N-2 and H2O), and a front aperture diameter of 0.8 mm. The new design concept is based upon "swiftly" accelerating the photoelectrons to kinetic energies of several keV after they pass the analyzer front aperture. Compared to the standard mode, in which the front section between the two first apertures is field-free, this gives a wider angular collection and a lower tendency for electron losses in collisions with gas molecules within the analyzer. With the swift-acceleration mode we attain, depending on the experimental conditions, up to about 3 times higher peak intensities in vacuum and about 10 to 20 times higher peak intensities in the 6-9 mbar regime, depending on kinetic energy. These experimental findings agree well with simulated transmission functions for the analyzer. The new mode of operation enables faster data acquisition than the standard mode of operation, particularly valuable in a home laboratory environment. Further demonstrations of performance are highlighted by measurements of the valence band structure in dye sensitized solar cell photoelectrodes under a 2 mbar H2O atmosphere, a molecularly modified surface of interest in photoelectrochemical devices.
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| 2. |
- Ellström, M, et al.
(författare)
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Evaluation of tissue trauma after laparoscopic and abdominal hysterectomy: measurements of neutrophil activation and release of interleukin-6, cortisol, and C-reactive protein.
- 1996
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Ingår i: Journal of the American College of Surgeons. - 1072-7515. ; 182:5, s. 423-30
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Trauma and major surgery stimulate a cascade of events that mediate the inflammatory response. The aim of our study was to determine whether or not hysterectomy leads to release of cytokines, cortisol, and C-reactive protein (CRP), activation of neutrophils, and activation of the complement cascade. A further aim was to compare laparoscopic and abdominal hysterectomy with regard to the same parameters. STUDY DESIGN: Twenty-four consecutive patients were randomized to either abdominal (n = 12) or laparoscopic hysterectomy (n = 12). Blood samples were drawn preoperatively, intraoperatively, and then at one minute, 24 hours, and seven days postoperatively. Interleukin-6 (IL-6) levels were used to evaluate cytokine release, cortisol and CRP to evaluate the inflammatory response, and polymorphonuclear (PMN) elastase to detect neutrophil activation. To evaluate complement activation, the terminal C5b-9 complement complex (TCC) was determined. RESULTS: Interleukin-6 concentrations were significantly elevated one minute and 24 hours postoperatively in both groups. Independent of the surgical technique or operative time, the highest IL-6 concentration was reached four hours after beginning the operation. Cortisol levels were significantly elevated during and after the operation in both groups. C-reactive peptide levels were significantly elevated in both groups 24 hours and seven days after the operation. Polymorphonuclear elastase was elevated 24 hours postoperatively in both groups. There were no signs of complement activation during the operative period or postoperatively in either patient group. CONCLUSIONS: Our results indicate serious tissue trauma during both laparoscopic and abdominal hysterectomy. The extent of surgical trauma did not differ between the two operative methods.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Marinado, Tannia, et al.
(författare)
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Surface Molecular Quantification and Photoelectrochemical Characterization of Mixed Organic Dye and Coadsorbent Layers on TiO2 for Dye-Sensitized Solar Cells
- 2010
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:27, s. 11903-11910
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Tidskriftsartikel (refereegranskat)abstract
- Different molecular layers on TiO2 were prepared by using the p-dimethylaniline triphenylamine based organic dye, D29, together with the coadsorbents decylphosphonic acid (DPA), dineohexyl bis(3,3-dimethylbutyl)phosphinic acid (DINHOP), and chenodeoxycholic acid (CDCA). The surface molecular structure of dye and coadsorbent layers on TiO2 was investigated by photoelectron spectroscopy (PES). A focus was to determine the surface molecular concentrations using characteristic photoelectron core levels. Dye-sensitized solar cells (DSCs) were prepared from the same substrate and were further characterized by photoelectrochemical methods. Together the investigation gives information on the arrangement of the mixed molecular layer and a first insight to the extent to which the coadsorbents exchange with dye molecules on the TiO2 surface for the examined conditions.
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| 7. |
- Berntsen, Magnus H., et al.
(författare)
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A spin- and angle-resolving photoelectron spectrometer
- 2010
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 81:3
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Tidskriftsartikel (refereegranskat)abstract
- A new type of hemispherical electron energy analyzer that permits angle and spin resolved photoelectron spectroscopy has been developed. The analyzer permits standard angle resolved spectra to be recorded with a two-dimensional detector in parallel with spin detection using a mini-Mott polarimeter. General design considerations as well as technical solutions are discussed and test results from the Au(111) surface state are presented.
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| 8. |
- Eriksson, Susanna K, et al.
(författare)
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A versatile photoelectron spectrometer for pressures up to 30 mbar
- 2014
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 85:7, s. 075119-
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Tidskriftsartikel (refereegranskat)abstract
- High-pressure photoelectron spectroscopy is a rapidly developing technique with applications in a wide range of fields ranging from fundamental surface science and catalysis to energy materials, environmental science, and biology. At present the majority of the high-pressure photoelectron spectrometers are situated at synchrotron end stations, but recently a small number of laboratory-based setups have also emerged. In this paper we discuss the design and performance of a new laboratory based high pressure photoelectron spectrometer equipped with an Al Ka X-ray anode and a hemispherical electron energy analyzer combined with a differentially pumped electrostatic lens. The instrument is demonstrated to be capable of measuring core level spectra at pressures up to 30 mbar. Moreover, valence band spectra of a silver sample as well as a carbon-coated surface (graphene) recorded under a 2 mbar nitrogen atmosphere are presented, demonstrating the versatility of this laboratory-based spectrometer.
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| 9. |
- Fredin, Kristofer, et al.
(författare)
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Solid state dye-sensitized solar cells prepared by infiltrating a molten hole conductor into a mesoporous film at a temperature below 150 degrees C
- 2011
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 161:21-22, s. 2280-2283
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Tidskriftsartikel (refereegranskat)abstract
- Infiltration of a molten hole conductor in a mesoporous film at an elevated temperature exhibits good wetting performance and the procedure is therefore suitable as part of the preparation method for solid state dye-sensitized solar cells. Herein, we present a system prepared by infiltrating 4-(diethylamino)benzaldehyde-1,1)-diphenyl-hydrazone in its molten form at a temperature below 150 degrees C. The system displays a maximum photon-to-current conversion efficiency of about 35%, a value corresponding to an increase of about 5 times in comparison with a previously published system prepared by infiltrating a molten hole-conductor at a temperature exceeding 250 degrees C. By means of comparing charge transport and recombination with the results measured for a liquid analogue, we conclude that whereas the transport rates are similar, recombination is significantly more rapid in the solid-state device.
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| 10. |
- Hahlin, Maria, et al.
(författare)
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A Photoelectron Spectroscopy Study of Z-907 Co-adsorbed with DPA on Nanostructured TiO2 Surfaces
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The surface electronic and molecular properties of mixed dye/coadsorbent sensitized TiO2 surfaces was investigated using photoelectron spectroscopy (PES). The sensitization of the TiO2 was performed using the ruthenium based dye cis-disothiocyanato-(2,2-bipyridyl-4,4-dicarboxylic acid)-(2,2-bipyridyl-4,4-dinonyl) ruthenium(II) (Z-907) together with different concentrations of the coadsorbent decylphosphonic acid (DPA). The investigation showed large variations in surface concentration of Z-907 and DPA depending on the dye/coadsorbent ratio in solution, but that the relative amounts at the surface and in solution substantially differ. Generally the DPA coadsorbents exchange with dye Z-907 molecule and trends in the surface concentration show that each dye molecule is replaced by six coadsorbent molecules. The co-adsorption of DPA induced changes in the S2p spectra, indicating changes in the dye surface interaction. Still, investigation of the frontier electronic structure in the dye sensitized TiO2 surfaces show that co-adsorbtion of DPA do not alter the energy level matching between the dye and the TiO2.
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| 11. |
- Hahlin, Maria, et al.
(författare)
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Electronic and molecular structures of organic dye/TiO2 interfaces for solar cell applications : a core level photoelectron spectroscopy study
- 2010
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 12:7, s. 1507-1517
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Tidskriftsartikel (refereegranskat)abstract
- The electronic and molecular properties of three organic dye molecules with the general structure donor-linker-anchor have been investigated using core level photoelectron spectroscopy (PES). The molecules contain a diphenylaniline donor unit, a thiophene linker unit, and cyanoacrylic acid or rhodanine-3-acetic acid anchor units. They have been investigated both in the form of a multilayer and adsorbed onto nanoporous TiO2 and the experimental results were also compared with DFT calculations. The changes at the dye-sensitized TiO2 surface due to the modification of either the donor unit or the anchor unit was investigated and the results showed important differences in coverage as well as in electronic and molecular surface properties. By measuring the core level binding energies, the sub-molecular properties were characterized and the result showed that the adsorption to the TiO2 influences the energy levels of the sub-molecular units differently.
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| 12. |
- Hahlin, Maria, et al.
(författare)
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Influence of Water on the Electronic : and Molecular Surface Structures of Ru-Dyes at Nanostructured TiO2
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:24, s. 11996-12004
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Tidskriftsartikel (refereegranskat)abstract
- The influence of water on the surface electronic and molecular properties of three Ru-dyes adsorbed at nanostructured TiO2 was investigated using photoelectron spectroscopy (PES). The dyes investigated were the Ru(dcbpy)(2)(NCS)(2) in its acid (N3) and in its 2-fold deprotonated form (N719) as well as a similar dye (Z-907) containing the hydrophobic ligand 4,4'-dinonyl-2,2'-bipyridine. Trends in surface structures depending on water exposure were followed for the three dyes. The results showed that the hydrophobic chains of the Z-907 dye effectively inhibit surface reorganization while large changes in surface electronic and molecular structure were observed for the N3 and N719 molecular layers. Specifically, large effects involving the thiocyanate ligands were detected, and the S2p and N Is core level spectra indicate that the changes involve mixing of only two dominating surface configurations. Moreover, the PES results also showed water-induced changes in the energy level matching between the dye and the TiO2, and water induced desorption of the TBA(+) counterion. Basic photoelectrochemical trends depending on water exposure to dye-sensitized solar cell systems were also verified.
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| 13. |
- Hahlin, Maria, 1975-, et al.
(författare)
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Surface compostions of dye/TiO2 interfaces formed from ethanol, acetonitrile, and dichloromethane based solutions
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The molecular and electronic surface structure of three TiO2 surfaces sensitized with 3-(5-(4-(diphenyl amino) styryl) thiophen-2-yl)-2-cyanoacrylic acid (D5) using different solvents (acetonitrile, dicloromethane, and ethanol) was investigated by photoelectron spectroscopy. The results showed solvent dependence in surface coverage, dye surface structure and energy level matching. Corresponding basic results on photocurrent conversion and UV-vis absorption is also included. Together the results indicated surface aggregation when using dichloromethane as a solvent.
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| 14. |
- Hahlin, Maria, et al.
(författare)
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The Influence of Water on the Electronic and Molecular Surface Structures of Ru-dyes at Nanostructured TiO2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The influence of water on the surface electronic and molecular properties of three Ru-dyes adsorbed at nanostructured TiO2 was investigated using photoelectron spectroscopy (PES). The dyes investigated were the Ru(dcbpy)2 (NCS)2 in its acid (N3) and in its 2-fold deprotonated form (N719) as well as a similar dye (Z-907) containing the hydrophobic ligand 4,4-dinonyl-2,2-bipyridine. Trends in surface structures depending on water exposure were followed for the three dyes. The results showed that the hydrophobic chains of the Z-907 dye effectively inhibit surface reorganization while large changes in surface electronic and molecular structure was observed for the N3 and N719 molecular layers. Specifically, large effects involving the thiocyanate ligands were detected and the S2p and N1s core level spectra indicate that the changes involve mixing of only two dominating surface configurations. Moreover, the PES results also showed water induced changes in the energy level matching between the dye and the TiO2, and water induced desorption of the TBA+ counter ion. Basic photoelectrochemical trends depending on water exposure to dye sensitized solar cell systems were also verified.
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| 15. |
- Kahk, J. Matthias, et al.
(författare)
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A study of the pressure profiles near the first pumping aperture in a high pressure photoelectron spectrometer
- 2015
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 205, s. 57-65
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Tidskriftsartikel (refereegranskat)abstract
- In a high-pressure photoelectron spectrometer, the sample is positioned close to a differential pumping aperture, behind which the pressure is several orders of magnitude lower than the pressure in the analysis chamber. To find the optimal sample position, where the path length of the photoelectrons through the high pressure region is minimized as far as possible without compromising knowledge of the actual pressure at the sample surface, an understanding of the pressure variations near the sample and the aperture is required. A computational fluid dynamics study has been carried out to examine the pressure profiles, and the results are compared against experimental spectra whose intensities are analyzed using the Beer-Lambert law. The resultant pressure profiles are broadly similar to the one previously derived from a simplistic molecular flow model, but indicate that as the pressure in the analysis chamber is raised, the region over which the pressure drop occurs becomes progressively narrower.
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| 16. |
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| 17. |
- Oscarsson, Johan, et al.
(författare)
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Coadsorption of Dye Molecules at TiO2 Surfaces : A Photoelectron Spectroscopy Study
- 2016
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:23, s. 12484-12494
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Tidskriftsartikel (refereegranskat)abstract
- The effects of coadsorbing the amphiphilic ruthenium-based dye Z907 (cis-bis(isothiocyanato)(2,20-bipyridy1-4,40-dicarboxylato)(4,40-dinony1-20-bipyridy1)-ruthenium(II)) with the coadsorbent DPA (n-decylphosphonic acid) and with the organic dye D35 ((E)-3-(5-(4-(bis(2',4'-dibutoxybiphenyl-4-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid) on mesoporous TiO2 were investigated using photoelectron spectroscopy (PES). Z907 is expected to adsorb to the TiO2 surface via the carboxylic acid groups. However, Z907 also shows signs of interacting with the TiO2 via the sulfur of the thiocyanate groups, and this interaction is affected by both the addition of DPA and D35. DPA, when added, exchanges with Z907 at the TiO2 surface, and each Z907 is replaced by six DPA molecules, but it does not affect the energy level alignment between Z907 and TiO2 substantially. Adding D35 to Z907 induces changes in the adsorption configuration of Z907 by the means of suppressing the interaction of the thiocyanate ligands and the TiO2 surface. The HOMO level of Z907 is shifted by the addition of D35. Coadsorbing Z907 with D35 thus gives changes at a molecular level, meaning that this is an example of collaborative sensitization.
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| 18. |
- Schölin, Rebecka, et al.
(författare)
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Preventing Dye Aggregation on ZnO by Adding Water in the Dye-Sensitization Process
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:39, s. 19274-19279
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Tidskriftsartikel (refereegranskat)abstract
- ZnO based dye-sensitized solar cells have been studied using N719 and Z-907 as sensitizing dyes, with and without including water to the dye solution. The solar cells have been characterized with photoelectric measurements and the interface between the dye and the ZnO surface has been studied using photoelectron spectroscopy. It was shown that water in the dye solution greatly reduces surface dye aggregation and thereby enhances the solar cell performance for N719. For Z-907 where no sign of dye aggregation could be found, the presence of water had minor effect on the surface structure and solar cell performance.
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