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| 2. |
- Biasin, Elisa, et al.
(författare)
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Femtosecond X-Ray Scattering Study of Ultrafast Photoinduced Structural Dynamics in Solvated[Co(terpy)2]2$
- 2016
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Ingår i: Physical Review Letters. - : American Physical Society (APS). - 1079-7114 .- 0031-9007. ; 117:1
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Tidskriftsartikel (refereegranskat)abstract
- We study the structural dynamics of photoexcited [Co(terpy)2]2+ in an aqueous solution with ultrafast x-ray diffuse scattering experiments conducted at the Linac Coherent Light Source. Through direct comparisons with density functional theory calculations, our analysis shows that the photoexcitation event leads to elongation of the Co-N bonds, followed by coherent Co-N bond length oscillations arising from the impulsive excitation of a vibrational mode dominated by the symmetrical stretch of all six Co-N bonds. This mode has a period of 0.33 ps and decays on a subpicosecond time scale. We find that the equilibrium bond-elongated structure of the high spin state is established on a single-picosecond time scale and that this state has a lifetime of ∼7 ps.
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| 3. |
- Canton, Sophie, et al.
(författare)
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Toward Highlighting the Ultrafast Electron Transfer Dynamics at the Optically Dark Sites of Photocatalysts
- 2013
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 4:11, s. 1972-1976
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Tidskriftsartikel (refereegranskat)abstract
- Building a detailed understanding of the structure function relationship is a crucial step in the optimization of molecular photocatalysts employed in water splitting schemes. The optically dark nature of their active sites usually prevents a complete mapping of the photoinduced dynamics. In this work, transient X-ray absorption spectroscopy highlights the electronic and geometric changes that affect such a center in a bimetallic model complex. Upon selective excitation of the ruthenium chromophore, the cobalt moiety is reduced through intramolecular electron transfer and undergoes a spin flip accompanied by an average bond elongation of 0.20 +/- 0.03 angstrom. The analysis is supported by simulations based on density functional theory structures (B3LYP*/TZVP) and FEFF 9.0 multiple scattering calculations. More generally, these results exemplify the large potential of the technique for tracking elusive intermediates that impart unique functionalities in photochemical devices.
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| 4. |
- Canton, Sophie, et al.
(författare)
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Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses.
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor-acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances. Experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.
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| 5. |
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| 6. |
- Johansson, Christian, et al.
(författare)
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Microwave circuits in multilayer inorganic-organic polymer thin film technology on laminate substrates
- 2003
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Ingår i: IEEE Transactions on Advanced Packaging. - 1521-3323 .- 1557-9980. ; 26:1, s. 81-89
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Tidskriftsartikel (refereegranskat)abstract
- Requirements of higher performance, reduced size, weight and cost of high-frequency (HF) devices has led to the search for new: materials, material combinations, methods, processes and production equipment. Efficient technologies for producing HF-circuits and integral passives are looked for. Also of interest are integrated packaging solutions for high frequency electrical packaging and optical interconnects and packaging. Sequentially build up multi-layers have been deposited on a low cost FR-4 epoxy substrate. The dielectric layers consist of a photo-patternable inorganic-organic hybrid polymer (ORMOCER) and the metallization is Cu. An UV-exposure equipment enabling projection patterning with 5 μm resolution have been used. The produced microstrip lines, ring resonators, vias, stacked capacitors and filters have been characterized at frequencies from 1 to 40 GHz showing the potential of the new dielectric materials and processing technologies for microwave applications.
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| 7. |
- Johansson, Christian, et al.
(författare)
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Microwave circuits in multilayer ORMOCER® thin film
- 2002
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Ingår i: Proceedings IMAPS Nordic 2002. ; , s. 60-63
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A multilayer sequential build-up structure for the integration of passivemicrowave devices is presented. The different devices were processed byusing a photo-patternable polymer ORMOCER together with conducting layersof Cu on top of a FR-4 substrate. Microstrip and stub structures have beencharacterised at frequencies between 1 to 40 GHZ showing the feasibility ofusing this kind of material and build-up technology for microwaveapplications.
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| 8. |
- Larsson Callerfelt, Anna-Karin, et al.
(författare)
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Modulation of antigen-induced responses by serotonin and prostaglandin E(2) via EP(1) and EP(4) receptors in the peripheral rat lung.
- 2013
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 699:1-3, s. 141-149
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Tidskriftsartikel (refereegranskat)abstract
- The cyclooxygenase (COX) pathway and prostanoids may critically contribute to the early allergic airway response. In the rat lung, serotonin (5-HT) is a major mediator of antigen-induced contractions. The aim of this study was therefore to examine the relative role of the COX pathway and serotonin for antigen-induced contractions in the rat lung. Airway responses were studied in rat precision-cut lung slices (PCLS). Lung slices were stimulated with ovalbumin or serotonin after pretreatment with COX inhibitors or specific TP or EP receptor antagonists. Changes in airway size (contractions/relaxations) were measured by a digital video camera. The supernatants were analysed for changes in prostaglandin and serotonin release. Airway contractions to ovalbumin were attenuated by the unselective COX inhibitor indomethacin, the selective COX-1 inhibitor FR-122047 and COX-2 inhibitor celecoxib. The EP(1) receptor antagonist ONO-8713 reduced the contractions, whereas the EP(4) receptor antagonist L-161,982 significantly increased the contractile response to ovalbumin. The 5-HT(2A) receptor antagonist ketanserin completely inhibited the ovalbumin-induced contractions. The different COX inhibitors decreased the production of prostaglandins but did not affect the synthesis of serotonin. The serotonin-induced bronchoconstriction was attenuated by celecoxib and ONO-8713, but not by methacholine. Taken together, our data indicate that PGE(2) is the main prostanoid involved in the early allergic airway response in the rat lung. PGE(2) appears to act both as a primary mediator of antigen-induced airway contraction via the EP(4) receptor and as a downstream modulator of serotonin-induced bronchoconstriction via the EP(1) receptor.
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| 9. |
- Polukeev, Alexey V., et al.
(författare)
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Iridium Catalyzed Dehydrogenation in a Continuous Flow Reactor as a Tool Towards Practical On-Board Hydrogen Generation From LOHCs
- 2022
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Ingår i: ChemSusChem. - : Wiley. - 1864-564X .- 1864-5631. ; 15:8
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Tidskriftsartikel (refereegranskat)abstract
- To enable the large-scale use of hydrogen fuel cells for mobility applications, convenient methods for on-board hydrogen storage and release need to be developed. A promising approach is liquid organic hydrogen carriers (LOHCs), since these are safe, available on a large scale and compatible with existing re-fuelling infrastructure. Usually, LOHC dehydrogenation is carried out in batch-type reactors by transition metals and their complexes and suffers from slow H 2 release kinetics and/or inability to reach high energy density by weight due to low conversion or the need to dilute the reaction mixture. Here we report the use of a continuous flow reactor in combination with a heterogenized iridium pincer complex, which enables a tremendous increase in LOHC dehydrogenation rates. Thus, dehydrogenation of isopropanol is performed in a regime that in terms of gravimetric energy density, hydrogen generation rate and precious metal content is potentially compatible with applications in a fuel-cell powered car.
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| 10. |
- Rein, Christian, et al.
(författare)
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Element-specific investigations of ultrafast dynamics in photoexcited Cu2ZnSnS4 nanoparticles in solution
- 2021
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafast, light-induced dynamics in copper-zinc-tin-sulfide (CZTS) photovoltaic nanoparticles are investigated through a combination of optical and x-ray transient absorption spectroscopy. Laser-pump, x-ray-probe spectroscopy on a colloidal CZTS nanoparticle ink yields element-specificity, which reveals a rapid photo-induced shift of electron density away from Cu-sites, affecting the molecular orbital occupation and structure of CZTS. We observe the formation of a stable charge-separated and thermally excited structure, which persists for nanoseconds and involves an increased charge density at the Zn sites. Combined with density functional theory calculations, the results provide new insight into the structural and electronic dynamics of CZTS absorbers for solar cells.
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