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 Speaker: Gerhard Grübel, Deutsches Elektronen-Synchrotron (DESY).
Date: 2010-06-01
Time: 14:15 - 15:15
Place: K-space (Q-building, room Q179), Physics department, Sölvegatan, Lund, Sweden.
About the speaker: Gerhard started his work at Brookhaven National Lab in the U.S. and joined the ESRF, France, in 1991 where he built the first beamline to operate at ESRF. In collaboration with other groups, he developed the X-ray photon correlation spectroscopy (XPCS), which exploits the coherent properties of synchrotron X-rays. He is now a senior scientist at HASYLAB at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany, where he is involved in the development of coherence based techniques for free-electron laser sources. Gerhard received the ninth 2009 Arthur H. Compton Award together with o Simon Mochrie (Yale University, New Haven, U.S.) and Mark Sutton (McGill University in Montreal, Canada) for their work on coherent scattering.
Abstract: The structure and dynamics of magnetic nanosystems is of both, fundamental and technologi cal interest. Ideally, one would like to probe magnetisation dynamics on a time scale of 100 femtoseconds (fs), with nanometre spatial resolution, while being able to do the measure ments element-specifically in order to account for the complex composition of actual mag netic media. Storage ring sources provide us with the necessary structural information while ultrafast magnetic scattering experiments require flashes of resonantly tuned soft X-rays that can be anticipated given the current construction of X-ray free-electron lasers (FEL) in Stan ford, CA, Hyogo, Japan and Hamburg, Germany. The FLASH facility in Hamburg already provides uniquely intense coherent short pulses in the EUV energy range with the shortest fundamental wave length l=6.1 nm. Using the fundamental wavelength l=7.97 nm it was pos sible to detect the fifth harmonic at 1.59 nm with an average energy of 3.5 nJ. This wave length corresponds to the Co L3 absorption edge and enabled us to perform the first resonant magnetic scattering experiment using FEL pulses of about 20 fs duration.
Contact person, ESS seminars:
Dr. Christian Vettier
E-mail: christian.vettier[at]esss.se
Mobile phone: +46 46 222 83 12 |
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 Speaker: John Larese, Professor and Joint ORNL Faculty, University of Tennessee, Knoxville, Oak Ridge National Laboratory, USA
Date: 2010-04-15
Time: 13:15 - 14:30
Place: Lecture hall B, Physics department, Sölvegatan, Lund, Sweden.
Abstract: There is tremendous interest in the synthesis and characterization of nanometer scale materials because they are predicted to exhibit physical and chemical properties that are dramatically different from ordinary matter. A direct consequence of the small number of atoms that make up each particle and the unique morphology or architecture that results (e.g. arrays of nanometer sized channels or cylindrical pores) is that nanomaterials exhibit a high surface-to-volume ratio. These systems are intriguing because they can confine molecules in one (1D-channels) or two (2D-surfaces) dimensions that are predicted to exhibit novel physical properties. While neutron scattering is not typically considered a surface sensitive probe, I will illustrate how we have used neutron scattering techniques to probe the microscopic structure and dynamics of molecules adsorbed on the surfaces or entrained within the pores of several highly uniform nanomaterials. The characterization also includes microscopy, thermodynamics and modeling to probe the nature of this novel behavior. Finally, I will discuss how current and future plans to construct high power neutron sources and novel instrumentation will spawn a new generation of discovery based surface investigations that will dramatically impact the world’s energy and technological future.
Contact person, ESS seminars:
Dr. Christian Vettier
E-mail: christian.vettier[at]esss.se
Mobile phone: +46 46 222 83 12 |
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 Speaker: Henrik Birkedal, Department of Chemistry & iNANO, Aarhus University, Denmark.
Date: 2010-03-17
Time: 14:15 - 15:00
Place: Lecture hall C, Chemistry department, Getingevägen 60, Lund, Sweden.
Abstract: Bone has a highly complex structure and is organized hierarchically from the atomic to the centimeter length scale – sort of like a molecular-scale Eiffel tower. It consists mainly of calcium phosphate nanocrystals and collagen type I fibers. The structure of bone determines its mechanical properties and hence its propensity for fracture. Bone structure is well understood down to around 10 micrometer; below this length scale many uncertainties remain. However, it is exactly at these length scales that bone quality is determined; i.e. the factors determining the risk of fracture.
We use small angle X-ray scattering (SAXS) to probe the structure of bone on the 1-100 nm length scale. By raster scanning the sample in the X-ray beam, maps of bone nanostructure can be obtained with a resolution corresponding to the X-ray beam diameter [1]. Using SAXS on bone, one is sensitive to the bone nanocrystals [2]. Two types of information can be obtained: the orientation of the crystallites and their thickness. Our methodologies for obtaining this information will be presented.
We will discuss examples of applications of SAXS on bone focusing on two distinct bone systems: the structural organization of growth plates, the loci of bone formation in growing juveniles [3], [4], and on Sr-treatment of osteoporosis [5].
- Paris, O., From diffraction to imaging: New avenues to study the hierarchical structure of biological tissues with X-ray microbeams. Biointerphases 2008, 3, FB1-FB26.
- Fratzl, P.; Fratzl-Zelman, N.; Klaushofer, K.; Vogl, G.; Koller, K., Nucleation and growth of mineral crystals in bone studied by small-angle X-ray scattering Calc. Tissue Int. 1991, 48, 407-413.
- Bünger, M. H.; Li, H.; Zou, X.; Langdahl, B.; Nygaard, J. V.; Bünger, C. E.; Besenbacher, F.; Pedersen, J. S.; Birkedal, H., Nanostructure of growing bones. In prepartion for Bone 2010.
- Bünger, M. H.; Foss, M.; Erlacher, K.; Hougaard, M. B.; Li, H.; Zou, X.; Langdahl, B.; Bünger, C.; Birkedal, H.; Besenbacher, F.; Pedersen, J. S., Nanostructure of the neurocentral growth plate: Insight from scanning small angle X-ray scattering, atomic force microscopy and scanning electron microscopy. Bone 2006, 39, 530-541.
- Bünger, M. H.; Oxlund, H.; Hansen, T. K.; Sørensen, S.; Bibby, B. M.; Thomsen, J. S.; Langdahl, B. L.; Besenbacher, F.; Pedersen, J. S.; Birkedal, H., Strontium and Bone Nanostructure in Normal and Ovariectomized Rats Investigated by Scanning Small-Angle X-Ray Scattering. Calc. Tissue Int. 2010, in press.
Download: Henrik Birkedal's presentation:
Download PDF 4.1 Mb |
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 Speaker: Sine Larsen, Department of Chemistry, University of Copenhagen, Denmark.
Date: 2010-02-26
Time: 14:15
Place: Chemistry department, K:B, Getingevägen 60, Lund
Abstract: Biological and soft matter samples have a lot of properties in common, they are complex, difficult to handle and weak scatters of X-rays. One way of improving the signal to noise ratio of the scattering signal is to use the small well focused very intense X-ray beams that have become available at the 3rd generation synchrotrons. The continuous exponential growth of protein structures that have been determined based on data measured with synchrotron radiation makes it fair to state that synchrotron radiation has revolutionized macromolecular crystallography. Similar achievements have been observed for Soft Matter research by the use of synchrotron radiation. The success in the use of the intense X-rays from synchrotrons on biological and soft matter samples is even more remarkable if one considers the rate by which the samples are destroyed in the intense synchrotron beams. Radiation damage imposes severe restrictions on the use of synchrotron radiation and the effects can be minimized by cooling the sample and optimization of the experimental set-up at the beamlines for macromolecular crystallography. Neutrons do not exert the same negative effect on biological and soft matter samples another advantage of using neutrons instead of photons is that they open the possibility to investigate the position and dynamics of hydrogen atoms. Examples will be presented on how the complementarities of X-rays and neutrons are exploited increasingly in investigations of biological and soft matter samples and how this has stimulated scientific partnerships that involve synchrotrons and neutron sources. |
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