| 1. |
- Lee, Myeong H., et al.
(author)
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Crystal structure, electronic structure, and vibrational properties of MAlSiH (M=Ca,Sr,Ba) : Hydrogenation-induced semiconductors from the AlB2-type alloys MAlSi
- 2008
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 78:19, s. 195209-
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Journal article (peer-reviewed)abstract
- Superconducting AlB2-type silicides CaAlSi, SrAlSi, and BaAlSi (MAlSi) absorb hydrogen and form semiconducting monohydrides where hydrogen is exclusively attached to Al. This induces a metal-nonmetal transition which is accompanied with only a minor rearrangement of the metal atoms. We report the synthesis and structure determination of CaAlSiH and BaAlSiH as well as a first-principles study of the electronic structure and vibrational property changes associated with the metal-nonmetal transition. We find that incorporation of H in MAlSi removes the partly occupied antibonding pi(*) band responsible for metallic behavior and turns it into an energetically low-lying Al-H bonding band. The fully occupied bonding pi band in MAlSi changes to a weakly dispersed band with Si p(z) (lone-pair) character in the hydrides, which becomes located below the Fermi level. The soft phonon mode in MAlSi pivotal for the superconducting properties stiffens considerably in the hydride. This mode is associated with the out-of-plane Al-Si vibration and is most affected by the formation of the Al-H bond. The mode of the Al-Si in-plane vibration, however, is unaffected, indicating that the Al-Si bond is equally strong in the metallic precursor and the semiconducting hydride. Al-H modes for MAlSiH are weakly dispersed. The frequencies of the stretching mode are around 1200 cm(-1) and virtually invariant to the M environment, indicating a covalent but weak Al-H interaction, which is interpreted as a dative bond from hydridic hydrogen to Al [Al <- H1-].
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| 2. |
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| 3. |
- Moser, D., et al.
(author)
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A series of BaAl2-xSixH2-x (0.4 < x < 1.6) hydrides with compositions and structures in between BaSi2 and BaAl2H2
- 2010
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In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 505:1, s. 1-5
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Journal article (peer-reviewed)abstract
- By substituting Si- with (Al-H)(-) in trigonal BaSi2, a series of hydrides has been synthesized with compositions BaAl2-xSixH2-x (0.4 < x < 1.6). OFF calculations show that the end compositions BaSi2 and BaAl2H2 are conductors whereas the intermediate BaAlSiH is a semiconductor. The cell parameters for the trigonal cell vary linearly as a function of the Si-/(Al-H)(-) substitution in this MgB2 related structure type, opening up the possibility of continuously tunable electric properties.
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| 4. |
- Nimmrich, Amke, 1995, et al.
(author)
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Solvent-Dependent Structural Dynamics in the Ultrafast Photodissociation Reaction of Triiodide Observed with Time-Resolved X-ray Solution Scattering
- 2023
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 145:29, s. 15754-15765
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Journal article (peer-reviewed)abstract
- Resolving the structural dynamics of bond breaking, bond formation, and solvation is required for a deeper understanding of solutionphase chemical reactions. In this work, we investigate the photodissociation of triiodide in four solvents using femtosecond time-resolved X-ray solution scattering following 400 nm photoexcitation. Structural analysis of the scattering data resolves the solvent-dependent structural evolution during the bond cleavage, internal rearrangements, solvent-cage escape, and bond reformation in real time. The nature and structure of the reaction intermediates during the recombination are determined, elucidating the full mechanism of photodissociation and recombination on ultrafast time scales. We resolve the structure of the precursor state for recombination as a geminate pair. Further, we determine the size of the solvent cages from the refined structures of the radical pair. The observed structural dynamics present a comprehensive picture of the solvent influence on structure and dynamics of dissociation reactions.
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| 5. |
- Björling, Alexander, 1983, et al.
(author)
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Ubiquitous Structural Signaling in Bacterial Phytochromes
- 2015
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In: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 6:17, s. 3379-3383
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Journal article (peer-reviewed)abstract
- The phytochrome family of light-switchable proteins has long been studied by biochemical, spectroscopic and crystallographic means, while a direct probe for global conformational signal propagation has been lacking. Using solution X-ray scattering, we find that the photosensory cores of several bacterial phytochromes undergo similar large-scale structural changes upon red-light excitation. The data establish that phytochromes with ordinary and inverted photocycles share a structural signaling mechanism and that a particular conserved histidine, previously proposed to be involved in signal propagation, in fact tunes photoresponse.
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| 6. |
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| 7. |
- Björling, Gunilla, Docent, et al.
(author)
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Risk Evaluation of Therapy Medical Devices and Implants for Increased Patient Safety : REMISS Horizon 2020 Research and Innovation Action
- 2017
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Conference paper (peer-reviewed)abstract
- Current knowledge in the area of medical devices remains insufficiently complete, and many of the established test methods and international standards (ISO (International Organization for Standardization) standards) open up to individual interpretation on how the test should be performed and the results reported. Treating long-term diseases such as cancer imposes a stringent sequence of various treatments on patients. For instance, cancer may be treated with radiation and chemotherapy; the latter in many treatment protocols requiring the implantation of an intravascular catheter during a prolonged period of time. To maximize the effect of such measures, as well as issues related to the patient Health Related Quality of Life (HRQoL), integrated and validated methodologies are needed as decisional basis for appropriate risk management and patient safety with regard to clinical use of intravascular catheters.The ambition of the REMISS project is to: Establish integrated and validated methodologies for risk management of the clinical use of intravascular catheters with respect to the clinical service lifetime, improved patient treatment, safety and HRQoL. This is assumed to reduce patient suffering due to complications associated with material deployment and degradation associated side effects for e.g. cancer patients receiving treatment with chemotherapeutical drugs using an intravascular catheter.The main vision is to improve the standards for eliminating side effects (complications) caused by deployment from and degradation of intravascular catheters, as well as loss of performance due to material-drug-biological system interactions, compared to the current state-of-the-art. Realising the project goals the rate of catheter-associated complications can be lowered by 40-50%, which in turn will improve patient treatment, safety and HRQoL, as well as health care related costs.Package integrally developed methodologies, predictive models, databases, and other project findings, as a potential product with a holistic coverage. It is believed that commercialisation of (selected) results will be the best option in order to create sustainable availability of this service based on continued research on intravascular catheters according to integrated and validated methodologies.REMISS answer the call NMBP-12-2017 Development of a Reliable Methodology for Better Risk Management of Engineered Biomaterials Advanced Therapy Medicinal Products and/or Medical Devices Marcy, P. Central venous access: techniques and indications in oncology. European Society of Radiology, 2008; 18; 2333-44 Maki DG, et al The risk of bloodstream infection in adults with different intravascular devices: a systematic review of 200 published prospective studies. Mayo Clin Proc 2006: 81 (9): 1159-71. Frostell, C., Björling, G., Strömberg, E., Karlsson, S., and Aune, R. E., Tracheal Implants Revisited, The Lancet (2017), 389(10075) pp.1191
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| 8. |
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| 9. |
- Björling, T., et al.
(author)
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SrAlSiH : A polyanionic semiconductor hydride
- 2005
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 44:44, s. 7269-7273
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Journal article (peer-reviewed)abstract
- (Chemical Equation Presented) Stable and semiconducting: Polyanionic hydrides represent a new class of main-group-metal hydrides with unforeseen hydrogen-coordination environments. The hydrogen atom in SrAlSiH is attached exclusively to Al and forms part of a layered [AlHSi]2- polyanion (see figure). This material is the first narrow bandgap semiconductor hydride and combines the high thermal stability of saline hydrides with the air and moisture stability of interstitial transition-metal hydrides.
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| 10. |
- Chayanun, Lert, et al.
(author)
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Combining Nanofocused X-Rays with Electrical Measurements at the NanoMAX Beamline
- 2019
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In: Crystals. - : MDPI AG. - 2073-4352. ; 9:8
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Journal article (peer-reviewed)abstract
- The advent of nanofocused X-ray beams has allowed the study of single nanocrystals and complete nanoscale devices in a nondestructive manner, using techniques such as scanning transmission X-ray microscopy (STXM), X-ray fluorescence (XRF) and X-ray diffraction (XRD). Further insight into semiconductor devices can be achieved by combining these techniques with simultaneous electrical measurements. Here, we present a system for electrical biasing and current measurement of single nanostructure devices, which has been developed for the NanoMAX beamline at the fourth-generation synchrotron, MAX IV, Sweden. The system was tested on single InP nanowire devices. The mechanical stability was sufficient to collect scanning XRD and XRF maps with a 50 nm diameter focus. The dark noise of the current measurement system was about 3 fA, which allowed fly scan measurements of X-ray beam induced current (XBIC) in single nanowire devices.
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