| 1. |
- Chapman, Henry N., et al.
(författare)
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Femtosecond diffractive imaging with a soft-X-ray free-electron laser
- 2006
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2473 .- 1745-2481. ; 2:12, s. 839-843
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Tidskriftsartikel (refereegranskat)abstract
- Theory predicts(1-4) that, with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft-X-ray free-electron laser. An intense 25 fs, 4 x 10(13) W cm(-2) pulse, containing 10(12) photons at 32 nm wavelength, produced a coherent diffraction pattern from a nanostructured non-periodic object, before destroying it at 60,000 K. A novel X-ray camera assured single-photon detection sensitivity by filtering out parasitic scattering and plasma radiation. The reconstructed image, obtained directly from the coherent pattern by phase retrieval through oversampling(5-9), shows no measurable damage, and is reconstructed at the diffraction-limited resolution. A three-dimensional data set may be assembled from such images when copies of a reproducible sample are exposed to the beam one by one(10).
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| 2. |
- Chapman, Henry N, et al.
(författare)
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Femtosecond time-delay X-ray holography
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 448:7154, s. 676-679
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Tidskriftsartikel (refereegranskat)abstract
- Extremely intense and ultrafast X-ray pulses from free-electron lasers offer unique opportunities to study fundamental aspects of complex transient phenomena in materials. Ultrafast time-resolved methods usually require highly synchronized pulses to initiate a transition and then probe it after a precisely defined time delay. In the X-ray regime, these methods are challenging because they require complex optical systems and diagnostics. Here we propose and apply a simple holographic measurement scheme, inspired by Newton's 'dusty mirror' experiment1, to monitor the X-ray-induced explosion of microscopic objects. The sample is placed near an X-ray mirror; after the pulse traverses the sample, triggering the reaction, it is reflected back onto the sample by the mirror to probe this reaction. The delay is encoded in the resulting diffraction pattern to an accuracy of one femtosecond, and the structural change is holographically recorded with high resolution. We apply the technique to monitor the dynamics of polystyrene spheres in intense free-electron-laser pulses, and observe an explosion occurring well after the initial pulse. Our results support the notion that X-ray flash imaging2, 3 can be used to achieve high resolution, beyond radiation damage limits for biological samples4. With upcoming ultrafast X-ray sources we will be able to explore the three-dimensional dynamics of materials at the timescale of atomic motion.
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| 3. |
- Hau-Riege, Stefan P., et al.
(författare)
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Encapsulation and diffraction-pattern-correction methods to reduce the effect of damage in x-ray diffraction imaging of single biological molecules
- 2007
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:19, s. 198302-
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Tidskriftsartikel (refereegranskat)abstract
- Short and intense x-ray pulses may be used for atomic-resolution diffraction imaging of single biological molecules. Radiation damage and a low signal-to-noise ratio impose stringent pulse requirements. In this Letter, we describe methods for decreasing the damage and improving the signal by encapsulating the molecule in a sacrificial layer (tamper) that reduces atomic motion and by postprocessing the pulse-averaged diffraction pattern to correct for ionization damage. Simulations show that these methods greatly improve the image quality.
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| 4. |
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| 5. |
- Szöke, Abraham, et al.
(författare)
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Energy Utilization, Catalysis and Evolution - Emergent Properties of Life
- 2007
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Ingår i: Current Chemical Biology. - : Bentham Science Publishers Ltd.. - 1872-3136. ; 1:1, s. 53-57
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Life is fueled by available energy. In fact, life is organized around the utilization of available energy, either from photons or from chemicals. The basic architecture of life can be understood from the following propositions: catalysts are able to control the path of chemical reactions and influence their rate by transient and reversible exchange of high-grade energy between themselves and reactants, while conserving the total energy. That, in turn, enables the synthesis of essential chemicals as well as the duplication of templates. We argue in this paper that energy utilization and evolution are emergent properties in life that are based on a small number of well-established laws of physics and chemistry governing catalysis. We propose that the relevant laws constitute a framework for biology on a level intermediate between quantum chemistry and cell biology.
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| 6. |
- Szöke, Abraham, et al.
(författare)
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Energy utilization in fluctuating biological energy converters
- 2016
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Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- We have argued previously [Szoke et al., FEBS Lett. 553, 18-20 (2003); Curr. Chem. Biol. 1, 53-57 (2007)] that energy utilization and evolution are emergent properties based on a small number of established laws of physics and chemistry. The relevant laws constitute a framework for biology on a level intermediate between quantum chemistry and cell biology. There are legitimate questions whether these concepts are valid at the mesoscopic level. Such systems fluctuate appreciably, so it is not clear what their efficiency is. Advances in fluctuation theorems allow the description of such systems on a molecular level. We attempt to clarify this topic and bridge the biochemical and physical descriptions of mesoscopic systems.
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