Institut für Meteorologie und Klimaforschung

Seminar über Aerosolphysik (IMK-AAF)

Ansprechpartner: Prof. Dr. T. Leisner, Dr. H. Saathoff, Dr. R. Wagner

Das Seminar findet - soweit nicht extra angekündigt - Montags um 11:00 Uhr im Seminarraum 150 des IMK-Gebäudes 326 (Campus Nord) statt.

Veranstaltungskalender

 
Seminar

Science at Free Electron Lasers Femtosecond X-ray Protein Nanocrystallography

Dienstag, 05. April 2011, 13:30-0:00
KIT, Campus Nord, IMK-AAF, Gebäude 326, Raum 150
The advent of free electron lasers (FELs) has opened up new opportunities to probe the structure of matter and the dynamics of ultrafast processes with unprecedented spatial and temporal resolution. New methods inaccessible with other known types of radiation sources can be developed to exploit these possibilities. One interesting application is the use of intense femtosecond X-ray pulses generated by FELs to perform crystallography on systems not accessible with the conventional radiation sources. X-ray crystallography provides indeed the vast majority of macromolecular structures, but the success of the method relies on having crystals of sufficient size. Unfortunately, it is often only possible to grow protein crystals up to the micrometer range or smaller, creating a large bottleneck in structure determination. The high brilliance of FELs sources gives the possibility to acquire diffraction patterns from single nano-crystals. Although the pulses are intense enough to cause molecular disintegration, it is possible to record diffraction patterns because the pulses are sufficiently short such that the diffraction process is completed before the molecules undergo significant structural change. Thousands of single nanocrystal patterns have to be acquired, indexed and then combined to give a 3D map of structure factors that can be phased using conventional single-crystal techniques. An experiment [1] performed at the Linac Coherent Light Source.(LCLS) allowed to solve the structure of the membrane protein Photosystem using the method described above. A 1.8 keV energy beam hitting a suspension of crystal smaller than 2 µm allowed obtaining an 8.5 Å resolution. Most recent experiments were carried out at a photon energy of 9.3 keV, with 2E11 photons per pulse focused to 10 µm2 (manuscript in preparation). Another interesting application of FELs is given by the application of crystallography method for imaging general non-periodic objects. Coherent X-ray pulses can be used to outrun key damage processes and obtain a single diffraction pattern from a single object before the sample explodes and turns into plasma. This idea has first been demonstrated at FLASH, where coherent diffraction patterns were acquired from nanostructured non-periodic objects before destroying them [2]. A recent paper [3] has shown that high-quality diffraction data with a single X-ray pulse can be obtained from a non-crystalline biological sample, a single mimivirus particle, which was injected into the pulsed beam of the LCLS. [1] H.N. Chapman et al., Femtosecond X-ray protein nanocrystallography Nature 470, 73-77 (2011) [2] H.N. Chapman et al., Femtosecond diffractive imaging with a soft-X-ray free-electron laser Nature Physics 2, 839-843 (2006) [3] M.M. Seibert et al., Single mimivirus particles intercepted and imaged with an X-ray laser Nature 470, 78-82 (2011)
Diese Veranstaltung ist Teil der Reihe Aerosolphysikalisches Seminar
Referent/in
Francesco Stellato

Center for Free Electron Laser science – DESY Hamburg
Veranstalter
Institut für Meteorologie und Klimaforschung
Karlsruher Institut für Technologie (KIT)
Hermann von Helmholtz Platz 1
76344 Eggenstein-Leopoldshafen
Tel: 0721-608-0
E-Mail: sekretariat does-not-exist.imk-asf kit edu
Servicemenü

Hinweise

"CS" - KIT-Campus Süd (Universität), Gebäude 30.23 (Physikhochhaus), Seminarraum 13/2

"CN" - KIT-Campus Nord (Forschungszentrum), Gebäude 435 (IMK), Raum 2.05

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