| 1. |
- Alonso-Mori, Roberto, et al.
(författare)
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Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:47, s. 19103-19107
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Tidskriftsartikel (refereegranskat)abstract
- The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this probe-before-destroy approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. K beta(1,3) XES spectra of Mn-II and Mn-2(III,IV) complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to > 100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II.
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| 2. |
- Bajt, Sasa, et al.
(författare)
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Camera for coherent diffractive imaging and holography with a soft-x-ray free-electron laser
- 2008
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 47:10, s. 1673-1683
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Tidskriftsartikel (refereegranskat)abstract
- We describe a camera to record coherent scattering patterns with a soft-x-ray free-electron laser (FEL). The camera consists of a laterally graded multilayer mirror, which reflects the diffraction pattern onto a CCD detector. The mirror acts as a bandpass filter for both the wavelength and the angle, which isolates the desired scattering pattern from nonsample scattering or incoherent emission from the sample. The mirror also solves the particular problem of the extreme intensity of the FEL pulses, which are focused to greater than 10(14) W/cm2. The strong undiffracted pulse passes through a hole in the mirror and propagates onto a beam dump at a distance behind the instrument rather than interacting with a beam stop placed near the CCD. The camera concept is extendable for the full range of the fundamental wavelength of the free electron laser in Hamburg (FLASH) FEL (i.e., between 6 and 60 nm) and into the water window. We have fabricated and tested various multilayer mirrors for wavelengths of 32, 16, 13.5, and 4.5 nm. At the shorter wavelengths mirror roughness must be minimized to reduce scattering from the mirror. We have recorded over 30,000 diffraction patterns at the FLASH FEL with no observable mirror damage or degradation of performance.
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| 3. |
- Barty, Anton, et al.
(författare)
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Ultrafast single-shot diffraction imaging of nanoscale dynamics
- 2008
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Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 2:7, s. 415-419
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Tidskriftsartikel (refereegranskat)abstract
- The transient nanoscale dynamics of materials on femtosecond to picosecond timescales is of great interest in the study of condensed phase dynamics such as crack formation, phase separation and nucleation, and rapid fluctuations in the liquid state or in biologically relevant environments. The ability to take images in a single shot is the key to studying non-repetitive behaviour mechanisms, a capability that is of great importance in many of these problems. Using coherent diffraction imaging with femtosecond X-ray free-electron-laser pulses we capture time-series snapshots of a solid as it evolves on the ultrafast timescale. Artificial structures imprinted on a Si3N4 window are excited with an optical laser and undergo laser ablation, which is imaged with a spatial resolution of 50 nm and a temporal resolution of 10 ps. By using the shortest available free-electron-laser wavelengths(1) and proven synchronization methods(2) this technique could be extended to spatial resolutions of a few nanometres and temporal resolutions of a few tens of femtoseconds. This experiment opens the door to a new regime of time-resolved experiments in mesoscopic dynamics.
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| 4. |
- Beyerlein, Kenneth, et al.
(författare)
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Ultrafast non-thermal heating of water initiated by an X-ray laser
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 115:22, s. 5652-5657
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Tidskriftsartikel (refereegranskat)abstract
- X-ray Free-Electron Lasers have opened the door to a new era in structural biology, enabling imaging of biomolecules and dynamics that were impossible to access with conventional methods. A vast majority of imaging experiments, including Serial Femtosecond Crystallography, use a liquid jet to deliver the sample into the interaction region. We have observed structural changes in the carrying water during X-ray exposure, showing how it transforms from the liquid phase to a plasma. This ultrafast phase transition observed in water provides evidence that any biological structure exposed to these X-ray pulses is destroyed during the X-ray exposure.The bright ultrafast pulses of X-ray Free-Electron Lasers allow investigation into the structure of matter under extreme conditions. We have used single pulses to ionize and probe water as it undergoes a phase transition from liquid to plasma. We report changes in the structure of liquid water on a femtosecond time scale when irradiated by single 6.86 keV X-ray pulses of more than 106 J/cm2. These observations are supported by simulations based on molecular dynamics and plasma dynamics of a water system that is rapidly ionized and driven out of equilibrium. This exotic ionic and disordered state with the density of a liquid is suggested to be structurally different from a neutral thermally disordered state.
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| 5. |
- Bogan, Michael J., et al.
(författare)
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Aerosol Imaging with a Soft X-Ray Free Electron Laser
- 2010
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 44:3, s. I-VI
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Tidskriftsartikel (refereegranskat)abstract
- Lasers have long played a critical role in the advancement of aerosol science. A new regime of ultrafast laser technology has recently be realized, the world's first soft x-ray free electron laser. The Free electron LASer in Hamburg, FLASH, user facility produces a steady source of 10 femtosecond pulses of 7–32 nm x-rays with 1012 photons per pulse. The high brightness, short wavelength, and high repetition rate (> 500 pulses per second) of this laser offers unique capabilities for aerosol characterization. Here we use FLASH to perform the highest resolution imaging of single PM2.5 aerosol particles in flight to date. We resolve to 35 nm the morphology of fibrous and aggregated spherical carbonaceous nanoparticles that existed for less than two milliseconds in vacuum. Our result opens the possibility for high spatial- and time-resolved single particle aerosol dynamics studies, filling a critical technological need in aerosol science.
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| 6. |
- Bogan, Michael J, et al.
(författare)
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Single particle X-ray diffractive imaging
- 2008
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 8:1, s. 310-6
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Tidskriftsartikel (refereegranskat)abstract
- In nanotechnology, strategies for the creation and manipulation of nanoparticles in the gas phase are critically important for surface modification and substrate-free characterization. Recent coherent diffractive imaging with intense femtosecond X-ray pulses has verified the capability of single-shot imaging of nanoscale objects at suboptical resolutions beyond the radiation-induced damage threshold. By intercepting electrospray-generated particles with a single 15 femtosecond soft-X-ray pulse, we demonstrate diffractive imaging of a nanoscale specimen in free flight for the first time, an important step toward imaging uncrystallized biomolecules.
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| 7. |
- Boutet, Jean-Sébastien
(författare)
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Welfare Mines : Extraction and Development in Postwar Northern Canada
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The role of extractive industries in development outcomes is a contested matter. The unresolved, provocative nature of modern mines, and in particular, of the industry’s self-positioning as an engine of local or regional improvement raises difficult problems for territorial, political, economic, cultural, and ontological sovereignty, in part because of the deeply hegemonic position it has assumed. This thesis broadly examines the interaction between two distinct but interrelating areas of development – resources extraction and human welfare – in northern Canada since the postwar period. I examine this question by following ideas and politics governing peoples and mines, and I explain how theories and practices of development evolved and intervened via industrial mining and the labour of Indigenous miners in northern Canada from 1945 up to the present. I present the results as a historical geography of state policy where mineral exploitation and human development intersect.Through a historical analysis grounded in a critical review of literature and the archival record, I consider economic progress and the closely linked mineral frontier advancement within Canada’s Arctic and subarctic regions, according to five periods: I Necessary interventions (1948–57); II Program for human betterment (1957–62); III Alternative development (1959–67); IV The dual economy (1968–84); and V Towards sustainable mines (1982–2005). Throughout this study, I adopt a comparative method in which I select multiple case examples that can, as a cumulative force, yield explanatory power. I do not conceive of the chosen industrial or mine sites as in-depth studies in their own right, but instead as part of a constellation of places that can serve to zoom in and out in order to cover a larger geographic unit spanning the Canadian north.A historical reconceptualization and a historicization of northern mines as locales of welfare making has revealed their ambiguous potential in bringing forth a radical transformation of peoples, lands, and societies in Canada. The pledge to improve societies based on the profitable exploitation of mineral resources arguably worked in lockstep with the delivery of large-scale mining to northern Canada; a double program I have come to view as the building of welfare mines. This thesis demonstrates that the welfare mines remain important sites where the apparent tension between money and peoples is used productively by the state. They are real-world places, material holes in the ground where mineral wealth is extracted but also where humans are reshaped, where both phenomena are inextricably woven within the overall rubric of development finally used to serve colonial governments. Welfare, insofar as it interacts with industrial development, participates, enables, is how mining capitalism works – welfare and exploitation necessarily coexist at northern mines. The welfare mines not only opened new possibilities in the north, they also served to foreclose other paths, thereby benefiting the mines in a self-reinforcing cycle. It is an all-embracing force that was not meant to be contained or to coincide with diverse modes of production or means of living. This is the power of welfare mines, a social power that illuminates the broader welfare mechanics of colonial power in northern Canada, and beyond.
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| 8. |
- Boutet, Sebastien, et al.
(författare)
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Ultrafast soft X-ray scattering and reference-enhanced diffractive imaging of weakly scattering nanoparticles
- 2008
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 166, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- We report the first successful reconstruction of the real space image from coherent X-ray diffraction patterns of membrane-supported nanoparticles using single ultrafast pulses. The particles consisted of 145-nm spherical polystyrene spheres that were size-selected by differential mobility analysis. We investigated the dependence of signal intensity on the number of spherical nanoparticles irradiated by single ultrafast pulses at the FLASH FEL facility. We demonstrate detection of as few as two 145-nm diameter particles irradiated by a single 32 nm fs-long FLASH pulse focused to 2.4Jcm(-2). In this case the noise in the diffraction pattern. due to photon-counting statistics and scattering from the supporting silicon nitride membrane, was the largest contributor to the recorded intensity. We were able to reconstruct high-resolution images of the nanoparticles using a strong scattering reference object to aid the phase retrieval of the coherent diffraction pattern. This method of reference-enhanced diffractive imaging may allow the imaging of weakly scattering objects at FLASH and other future X-ray FEL sources.
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| 9. |
- Brändén, Gisela, 1975, et al.
(författare)
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Coherent diffractive imaging of microtubules using an X-ray laser.
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- X-ray free electron lasers (XFELs) create new possibilities for structural studies of biological objects that extend beyond what is possible with synchrotron radiation. Serial femtosecond crystallography has allowed high-resolution structures to be determined from micro-meter sized crystals, whereas single particle coherent X-ray imaging requires development to extend the resolution beyond a few tens of nanometers. Here we describe an intermediate approach: the XFEL imaging of biological assemblies with helical symmetry. We collected X-ray scattering images from samples of microtubules injected across an XFEL beam using a liquid microjet, sorted these images into class averages, merged these data into a diffraction pattern extending to 2nm resolution, and reconstructed these data into a projection image of the microtubule. Details such as the 4nm tubulin monomer became visible in this reconstruction. These results illustrate the potential of single-molecule X-ray imaging of biological assembles with helical symmetry at room temperature.
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| 10. |
- 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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