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Author

H. Gorke

Bio: H. Gorke is an academic researcher from Forschungszentrum Jülich. The author has contributed to research in topics: Hyperfine structure & Deuterium. The author has an hindex of 14, co-authored 38 publications receiving 3465 citations.

Papers
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Journal ArticleDOI
Henry N. Chapman1, Petra Fromme2, Anton Barty, Thomas A. White, Richard A. Kirian2, Andrew Aquila, Mark S. Hunter2, Joachim Schulz, Daniel P. DePonte, Uwe Weierstall2, R. Bruce Doak2, Filipe R. N. C. Maia3, Andrew V. Martin, Ilme Schlichting4, Lukas Lomb4, Nicola Coppola5, Robert L. Shoeman4, Sascha W. Epp4, Robert Hartmann, Daniel Rolles4, Artem Rudenko4, Lutz Foucar4, Nils Kimmel4, Georg Weidenspointner4, Peter Holl, Mengning Liang, Miriam Barthelmess, Carl Caleman, Sébastien Boutet6, Michael J. Bogan6, Jacek Krzywinski6, Christoph Bostedt6, Saša Bajt, Lars Gumprecht, Benedikt Rudek4, Benjamin Erk4, Carlo Schmidt4, André Hömke4, Christian Reich, Daniel Pietschner4, Lothar Strüder4, Günter Hauser4, H. Gorke7, Joachim Ullrich4, Sven Herrmann4, Gerhard Schaller4, Florian Schopper4, Heike Soltau, Kai-Uwe Kühnel4, Marc Messerschmidt6, John D. Bozek6, Stefan P. Hau-Riege8, Matthias Frank8, Christina Y. Hampton6, Raymond G. Sierra6, Dmitri Starodub6, Garth J. Williams6, Janos Hajdu3, Nicusor Timneanu3, M. Marvin Seibert6, M. Marvin Seibert3, Jakob Andreasson3, Andrea Rocker3, Olof Jönsson3, Martin Svenda3, Stephan Stern, Karol Nass1, Robert Andritschke4, Claus Dieter Schröter4, Faton Krasniqi4, Mario Bott4, Kevin Schmidt2, Xiaoyu Wang2, Ingo Grotjohann2, James M. Holton9, Thomas R. M. Barends4, Richard Neutze10, Stefano Marchesini9, Raimund Fromme2, Sebastian Schorb11, Daniela Rupp11, M. Adolph11, Tais Gorkhover11, Inger Andersson12, Helmut Hirsemann, Guillaume Potdevin, Heinz Graafsma, Björn Nilsson, John C. H. Spence2 
03 Feb 2011-Nature
TL;DR: This work offers a new approach to structure determination of macromolecules that do not yield crystals of sufficient size for studies using conventional radiation sources or are particularly sensitive to radiation damage, by using pulses briefer than the timescale of most damage processes.
Abstract: X-ray crystallography provides the vast majority of macromolecular structures, but the success of the method relies on growing crystals of sufficient size. In conventional measurements, the necessary increase in X-ray dose to record data from crystals that are too small leads to extensive damage before a diffraction signal can be recorded(1-3). It is particularly challenging to obtain large, well-diffracting crystals of membrane proteins, for which fewer than 300 unique structures have been determined despite their importance in all living cells. Here we present a method for structure determination where single-crystal X-ray diffraction 'snapshots' are collected from a fully hydrated stream of nanocrystals using femtosecond pulses from a hard-X-ray free-electron laser, the Linac Coherent Light Source(4). We prove this concept with nanocrystals of photosystem I, one of the largest membrane protein complexes(5). More than 3,000,000 diffraction patterns were collected in this study, and a three-dimensional data set was assembled from individual photosystem I nanocrystals (similar to 200 nm to 2 mm in size). We mitigate the problem of radiation damage in crystallography by using pulses briefer than the timescale of most damage processes(6). This offers a new approach to structure determination of macromolecules that do not yield crystals of sufficient size for studies using conventional radiation sources or are particularly sensitive to radiation damage.

1,708 citations

Journal ArticleDOI
M. Marvin Seibert1, Tomas Ekeberg1, Filipe R. N. C. Maia1, Martin Svenda1, Jakob Andreasson1, Olof Jönsson1, Dusko Odic1, Bianca Iwan1, Andrea Rocker1, Daniel Westphal1, Max F. Hantke1, Daniel P. DePonte, Anton Barty, Joachim Schulz, Lars Gumprecht, Nicola Coppola, Andrew Aquila, Mengning Liang, Thomas A. White, Andrew V. Martin, Carl Caleman1, Stephan Stern2, Chantal Abergel3, Virginie Seltzer3, Jean-Michel Claverie3, Christoph Bostedt4, John D. Bozek4, Sébastien Boutet4, A. Miahnahri4, Marc Messerschmidt4, Jacek Krzywinski4, Garth J. Williams4, Keith O. Hodgson4, Michael J. Bogan4, Christina Y. Hampton4, Raymond G. Sierra4, D. Starodub4, Inger Andersson5, Sǎa Bajt, Miriam Barthelmess, John C. H. Spence6, Petra Fromme6, Uwe Weierstall6, Richard A. Kirian6, Mark S. Hunter6, R. Bruce Doak6, Stefano Marchesini7, Stefan P. Hau-Riege8, Matthias Frank8, Robert L. Shoeman9, Lukas Lomb9, Sascha W. Epp9, Robert Hartmann, Daniel Rolles9, Artem Rudenko9, Carlo Schmidt9, Lutz Foucar9, Nils Kimmel9, Peter Holl, Benedikt Rudek9, Benjamin Erk9, André Hömke9, Christian Reich, Daniel Pietschner9, Georg Weidenspointner9, Lothar Strüder9, Günter Hauser9, H. Gorke, Joachim Ullrich9, Ilme Schlichting9, Sven Herrmann9, Gerhard Schaller9, Florian Schopper9, Heike Soltau, Kai Uwe Kuhnel9, Robert Andritschke9, Claus Dieter Schröter9, Faton Krasniqi9, Mario Bott9, Sebastian Schorb10, Daniela Rupp10, M. Adolph10, Tais Gorkhover10, Helmut Hirsemann, Guillaume Potdevin, Heinz Graafsma, Björn Nilsson, Henry N. Chapman2, Janos Hajdu1 
03 Feb 2011-Nature
TL;DR: This work shows that high-quality diffraction data can be obtained with a single X-ray pulse from a non-crystalline biological sample, a single mimivirus particle, which was injected into the pulsed beam of a hard-X-ray free-electron laser, the Linac Coherent Light Source.
Abstract: The start-up of the Linac Coherent Light Source (LCLS), the new femtosecond hard X-ray laser facility in Stanford, California, has brought high expectations of a new era for biological imaging. The intense, ultrashort X-ray pulses allow diffraction imaging of small structures before radiation damage occurs. Two papers in this issue of Nature present proof-of-concept experiments showing the LCLS in action. Chapman et al. tackle structure determination from nanocrystals of macromolecules that cannot be grown in large crystals. They obtain more than three million diffraction patterns from a stream of nanocrystals of the membrane protein photosystem I, and assemble a three-dimensional data set for this protein. Seibert et al. obtain images of a non-crystalline biological sample, mimivirus, by injecting a beam of cooled mimivirus particles into the X-ray beam. The start-up of the new femtosecond hard X-ray laser facility in Stanford, the Linac Coherent Light Source, has brought high expectations for a new era for biological imaging. The intense, ultrashort X-ray pulses allow diffraction imaging of small structures before radiation damage occurs. This new capability is tested for the problem of imaging a non-crystalline biological sample. Images of mimivirus are obtained, the largest known virus with a total diameter of about 0.75 micrometres, by injecting a beam of cooled mimivirus particles into the X-ray beam. The measurements indicate no damage during imaging and prove the concept of this imaging technique. X-ray lasers offer new capabilities in understanding the structure of biological systems, complex materials and matter under extreme conditions1,2,3,4. Very short and extremely bright, coherent X-ray pulses can be used to outrun key damage processes and obtain a single diffraction pattern from a large macromolecule, a virus or a cell before the sample explodes and turns into plasma1. The continuous diffraction pattern of non-crystalline objects permits oversampling and direct phase retrieval2. Here we show that high-quality diffraction data can be obtained with a single X-ray pulse from a non-crystalline biological sample, a single mimivirus particle, which was injected into the pulsed beam of a hard-X-ray free-electron laser, the Linac Coherent Light Source5. Calculations indicate that the energy deposited into the virus by the pulse heated the particle to over 100,000 K after the pulse had left the sample. The reconstructed exit wavefront (image) yielded 32-nm full-period resolution in a single exposure and showed no measurable damage. The reconstruction indicates inhomogeneous arrangement of dense material inside the virion. We expect that significantly higher resolutions will be achieved in such experiments with shorter and brighter photon pulses focused to a smaller area. The resolution in such experiments can be further extended for samples available in multiple identical copies.

838 citations

Journal ArticleDOI
TL;DR: The results suggest that a magnetic material's microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1 ps) spin reversal than in present technologies.
Abstract: Ultrafast laser techniques have revealed extraordinary spin dynamics in magnetic materials that equilibrium descriptions of magnetism cannot explain. Particularly important for future applications is understanding non-equilibrium spin dynamics following laser excitation on the nanoscale, yet the limited spatial resolution of optical laser techniques has impeded such nanoscale studies. Here we present ultrafast diffraction experiments with an X-ray laser that probes the nanoscale spin dynamics following optical laser excitation in the ferrimagnetic alloy GdFeCo, which exhibits macroscopic all-optical switching. Our study reveals that GdFeCo displays nanoscale chemical and magnetic inhomogeneities that affect the spin dynamics. In particular, we observe Gd spin reversal in Gd-rich nanoregions within the first picosecond driven by the non-local transfer of angular momentum from larger adjacent Fe-rich nanoregions. These results suggest that a magnetic material's microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1 ps) spin reversal than in present technologies.

285 citations

Journal ArticleDOI
TL;DR: The plasma dynamics of single mesoscopic Xe particles irradiated with intense femtosecond x-ray pulses exceeding 10(16) W/cm2 from the Linac Coherent Light Source free-electron laser are investigated and show that for clusters illuminated with intense x-Ray pulses, highly charged ionization fragments in a narrow distribution are created.
Abstract: The plasma dynamics of single mesoscopic Xe particles irradiated with intense femtosecond x-ray pulses exceeding ${10}^{16}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ from the Linac Coherent Light Source free-electron laser are investigated. Simultaneous recording of diffraction patterns and ion spectra allows eliminating the influence of the laser focal volume intensity and particle size distribution. The data show that for clusters illuminated with intense x-ray pulses, highly charged ionization fragments in a narrow distribution are created and that the nanoplasma recombination is efficiently suppressed.

252 citations

Journal ArticleDOI
TL;DR: In this article, the authors reported an unprecedented high degree of ionization of xenon atoms by 1.5 keV free-electron laser pulses to charge states with ionization energies far exceeding the photon energy.
Abstract: X-ray free-electron lasers provide unique opportunities for exploring ultrafast dynamics and for imaging the structures of complex systems. Understanding the response of individual atoms to intense X-rays is essential for most free-electron laser applications. First experiments have shown that, for light atoms, the dominant interaction mechanism is ionization by sequential electron ejection, where the highest charge state produced is defined by the last ionic state that can be ionized with one photon. Here, we report an unprecedentedly high degree of ionization of xenon atoms by 1.5 keV free-electron laser pulses to charge states with ionization energies far exceeding the photon energy. Comparing ion charge-state distributions and fluorescence spectra with state-of-the-art calculations, we find that these surprisingly high charge states are created via excitation of transient resonances in highly charged ions, and predict resonance enhanced absorption to be a general phenomenon in the interaction of intense X-rays with systems containing high-Z constituents. Researchers create high ionization states, up to Xe36+, using 1.5 keV free-electron laser pulses. The higher than expected ionization may be due to transient resonance-enhanced absorption and the effect may play an important role in interactions of intense X-rays with high-Z elements and radiation damage.

213 citations


Cited by
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01 Oct 2019
TL;DR: Recent developments in the Phenix software package are described in the context of macromolecular structure determination using X-rays, neutrons and electrons.
Abstract: Diffraction (X-ray, neutron and electron) and electron cryo-microscopy are powerful methods to determine three-dimensional macromolecular structures, which are required to understand biological processes and to develop new therapeutics against diseases. The overall structure-solution workflow is similar for these techniques, but nuances exist because the properties of the reduced experimental data are different. Software tools for structure determination should therefore be tailored for each method. Phenix is a comprehensive software package for macromolecular structure determination that handles data from any of these techniques. Tasks performed with Phenix include data-quality assessment, map improvement, model building, the validation/rebuilding/refinement cycle and deposition. Each tool caters to the type of experimental data. The design of Phenix emphasizes the automation of procedures, where possible, to minimize repetitive and time-consuming manual tasks, while default parameters are chosen to encourage best practice. A graphical user interface provides access to many command-line features of Phenix and streamlines the transition between programs, project tracking and re-running of previous tasks.

3,268 citations

Journal ArticleDOI
TL;DR: In this paper, the European Photon Imaging Camera (EPIC) consortium has provided the focal plane instruments for the three X-ray mirror systems on XMM-Newton, including two cameras with a reflecting grating spectrometer in the optical path equipped with MOS type CCDs as focal plane detectors.
Abstract: The European Photon Imaging Camera (EPIC) consortium has provided the focal plane instruments for the three X-ray mirror systems on XMM-Newton. Two cameras with a reflecting grating spectrometer in the optical path are equipped with MOS type CCDs as focal plane detectors (Turner 2001), the telescope with the full photon flux operates the novel pn-CCD as an imaging X-ray spectrometer. The pn-CCD camera system was developed under the leadership of the Max-Planck-Institut fur extraterrestrische Physik (MPE), Garching. The concept of the pn-CCD is described as well as the dierent operational modes of the camera system. The electrical, mechanical and thermal design of the focal plane and camera is briefly treated. The in-orbit performance is described in terms of energy resolution, quantum eciency, time resolution, long term stability and charged particle background. Special emphasis is given to the radiation hardening of the devices and the measured and expected degradation due to radiation damage of ionizing particles in the rst 9 months of in orbit operation.

2,933 citations

Journal ArticleDOI
TL;DR: This review extensively discusses the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral,Anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti- cancer activity of Ag NPs.
Abstract: Recent advances in nanoscience and nanotechnology radically changed the way we diagnose, treat, and prevent various diseases in all aspects of human life. Silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. AgNPs play an important role in nanoscience and nanotechnology, particularly in nanomedicine. Although several noble metals have been used for various purposes, AgNPs have been focused on potential applications in cancer diagnosis and therapy. In this review, we discuss the synthesis of AgNPs using physical, chemical, and biological methods. We also discuss the properties of AgNPs and methods for their characterization. More importantly, we extensively discuss the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti-cancer activity of AgNPs. In addition, we discuss therapeutic approaches and challenges for cancer therapy using AgNPs. Finally, we conclude by discussing the future perspective of AgNPs.

1,720 citations

Journal ArticleDOI
TL;DR: Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand.
Abstract: Two major energy-related problems confront the world in the next 50 years. First, increased worldwide competition for gradually depleting fossil fuel reserves (derived from past photosynthesis) will lead to higher costs, both monetarily and politically. Second, atmospheric CO_2 levels are at their highest recorded level since records began. Further increases are predicted to produce large and uncontrollable impacts on the world climate. These projected impacts extend beyond climate to ocean acidification, because the ocean is a major sink for atmospheric CO2.1 Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand.

1,651 citations

Journal ArticleDOI
TL;DR: The goal is to describe the current state of the art in this area, identify challenges, and suggest future directions and areas where signal processing methods can have a large impact on optical imaging and on the world of imaging at large.
Abstract: i»?The problem of phase retrieval, i.e., the recovery of a function given the magnitude of its Fourier transform, arises in various fields of science and engineering, including electron microscopy, crystallography, astronomy, and optical imaging. Exploring phase retrieval in optical settings, specifically when the light originates from a laser, is natural since optical detection devices [e.g., charge-coupled device (CCD) cameras, photosensitive films, and the human eye] cannot measure the phase of a light wave. This is because, generally, optical measurement devices that rely on converting photons to electrons (current) do not allow for direct recording of the phase: the electromagnetic field oscillates at rates of ~1015 Hz, which no electronic measurement device can follow. Indeed, optical measurement/detection systems measure the photon flux, which is proportional to the magnitude squared of the field, not the phase. Consequently, measuring the phase of optical waves (electromagnetic fields oscillating at 1015 Hz and higher) involves additional complexity, typically by requiring interference with another known field, in the process of holography.

869 citations