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Clemens Weninger - One of the best experts on this subject based on the ideXlab platform.
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X Ray emission spectroscopy as an in situ diagnostic tool for X Ray crystallography of metalloproteins using an X Ray free electron laser
Biochemistry, 2018Co-Authors: Thomas Fransson, Thomas Kroll, Dimosthenis Sokaras, Uwe Bergmann, Ruchira Chatterjee, Franklin D Fuller, Clemens Weninger, Roberto Alonsomori, Jan Kern, Vittal K YachandraAbstract:Serial femtosecond crystallography (SFX) using the ultrashort X-Ray pulses from a X-Ray free-electron laser (XFEL) provides a new way of collecting structural data at room temperature that allows for following the reaction in real time after initiation. XFEL eXperiments are conducted in a shot-by-shot mode as the sample is destroyed and replenished after each X-Ray pulse, and therefore, monitoring and controlling the data quality by using in situ diagnostic tools is critical. To study metalloenzymes, we developed the use of simultaneous collection of X-Ray diffraction of crystals along with X-Ray emission spectroscopy (XES) data that is used as a diagnostic tool for crystallography, by monitoring the chemical state of the metal catalytic center. We have optimized data analysis methods and sample delivery techniques for fast and active feedback to ensure the quality of each batch of samples and the turnover of the catalytic reaction caused by reaction triggering methods. Here, we describe this active in si...
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stimulated X Ray raman scattering a critical assessment of the building block of nonlinear X Ray spectroscopy
Faraday Discussions, 2016Co-Authors: Alberto Lutman, Clemens Weninger, Victor Kimberg, Alvaro Sanchezgonzalez, Laurent Mercadier, Daniel Ratner, Ryan Coffee, Maximilian BucherAbstract:With the invention of femtosecond X-Ray free-electron lasers (XFELs), studies of light-induced chemical reaction dynamics and structural dynamics reach a new era, allowing for time-resolved X-Ray diffraction and spectroscopy. To ultimately probe coherent electron and nuclear dynamics on their natural time and length scales, coherent nonlinear X-Ray spectroscopy schemes have been proposed. In this contribution, we want to critically assess the eXperimental realisation of nonlinear X-Ray spectroscopy at current-day XFEL sources, by presenting first eXperimental attempts to demonstrate stimulated resonant X-Ray Raman scattering in molecular gas targets.
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stimulated electronic X Ray raman scattering
Physical Review Letters, 2013Co-Authors: Clemens Weninger, J.j. Rocca, Christoph Bostedt, Michael Purvis, Duncan P Ryan, Richard A London, J D Bozek, Alexander Graf, G V Brown, Nina RohringerAbstract:We demonstrate strong stimulated inelastic X-Ray scattering by resonantly eXciting a dense gas target of neon with femtosecond, high-intensity X-Ray pulses from an X-Ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic X-Ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered X-Ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic X-Ray scattering, with spectral resolution smaller than the natural width of the core-eXcited, intermediate state.
P G Jonker - One of the best experts on this subject based on the ideXlab platform.
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the X Ray spectral evolution of galactic black hole X Ray binaries toward quiescence
The Astrophysical Journal, 2013Co-Authors: Richard M Plotkin, Elena Gallo, P G JonkerAbstract:Most transient black hole X-Ray binaries (BHXBs) spend the bulk of their time in a quiescent state, where they accrete matter from their companion star at highly sub-Eddington luminosities (we define quiescence here as a normalized Eddington ratio lX = L 0.5-10 keV/L Edd < 10–5). Here, we present Chandra X-Ray imaging spectroscopy for three BHXB systems (H 1743–322, MAXI J1659–152, and XTE J1752–223) as they fade into quiescence following an outburst. Multiple X-Ray observations were taken within one month of each other, allowing us to track each individual system's X-Ray spectral evolution during its decay. We compare these three systems to other BHXB systems. We confirm that quiescent BHXBs have softer X-Ray spectra than low-hard-state BHXBs, and that quiescent BHXB spectral properties show no dependence on the binary system's orbital parameters. However, the observed anti-correlation between X-Ray photon indeX (Γ) and lX in the low-hard state does not continue once a BHXB enters quiescence. Instead, Γ plateaus to an average Γ = 2.08 ± 0.07 by the time lX reaches ~10–5. lX ~ 10–5 is thus an observationally motivated upper limit for the beginning of the quiescent spectral state. Our results are discussed in the conteXt of different accretion flow models and across the black hole mass scale.
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the X Ray spectral evolution of galactic black hole X Ray binaries toward quiescence
arXiv: High Energy Astrophysical Phenomena, 2013Co-Authors: Richard M Plotkin, Elena Gallo, P G JonkerAbstract:Most transient black hole X-Ray binaries (BHXBs) spend the bulk of their time in a quiescent state, where they accrete matter from their companion star at highly sub-Eddington luminosities (we define quiescence here as a normalized Eddington ratio l_X = L_{0.5-10 keV}}/L_{Edd} < 1e-5). Here, we present Chandra X-Ray imaging spectroscopy for three BHXB systems (H 1743-322, MAXI J1659-152, and XTE J1752-223) as they fade into quiescence following an outburst. Multiple X-Ray observations were taken within one month of each other, allowing us to track each individual system's X-Ray spectral evolution during its decay. We compare these three systems to other BHXB systems. We confirm that quiescent BHXBs have softer X-Ray spectra than low-hard state BHXBs, and that quiescent BHXB spectral properties show no dependence on the binary system's orbital parameters. However, the observed anti-correlation between X-Ray photon indeX and l_X in the low-hard state does not continue once a BHXB enters quiescence. Instead, the photon indeX plateaus to an average value of 2.08+/-0.07 by the time l_X reaches approXimately 1e-5. l_X~1e-5 is thus an observationally-motivated upper limit for the beginning of the quiescent spectral state. Our results are discussed in the conteXt of different accretion flow models, and across the black hole mass scale.
Vittal K Yachandra - One of the best experts on this subject based on the ideXlab platform.
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X Ray emission spectroscopy as an in situ diagnostic tool for X Ray crystallography of metalloproteins using an X Ray free electron laser
Biochemistry, 2018Co-Authors: Thomas Fransson, Thomas Kroll, Dimosthenis Sokaras, Uwe Bergmann, Ruchira Chatterjee, Franklin D Fuller, Clemens Weninger, Roberto Alonsomori, Jan Kern, Vittal K YachandraAbstract:Serial femtosecond crystallography (SFX) using the ultrashort X-Ray pulses from a X-Ray free-electron laser (XFEL) provides a new way of collecting structural data at room temperature that allows for following the reaction in real time after initiation. XFEL eXperiments are conducted in a shot-by-shot mode as the sample is destroyed and replenished after each X-Ray pulse, and therefore, monitoring and controlling the data quality by using in situ diagnostic tools is critical. To study metalloenzymes, we developed the use of simultaneous collection of X-Ray diffraction of crystals along with X-Ray emission spectroscopy (XES) data that is used as a diagnostic tool for crystallography, by monitoring the chemical state of the metal catalytic center. We have optimized data analysis methods and sample delivery techniques for fast and active feedback to ensure the quality of each batch of samples and the turnover of the catalytic reaction caused by reaction triggering methods. Here, we describe this active in si...
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X-Ray absorption spectroscopy.
Photosynthesis research, 2009Co-Authors: Junko Yano, Vittal K YachandraAbstract:This review gives a brief description of the theory and application of X-Ray absorption spectroscopy, both X-Ray absorption near-edge structure (XANES) and eXtended X-Ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in eXtended EXAFS and polarized EXAFS using oriented membranes and single crystals are eXplained. Developments in theory in understanding the XANES spectra are described. The application of X-Ray absorption spectroscopy to the study of the Mn(4)Ca cluster in Photosystem II is presented.
Nina Rohringer - One of the best experts on this subject based on the ideXlab platform.
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stimulated electronic X Ray raman scattering
Physical Review Letters, 2013Co-Authors: Clemens Weninger, J.j. Rocca, Christoph Bostedt, Michael Purvis, Duncan P Ryan, Richard A London, J D Bozek, Alexander Graf, G V Brown, Nina RohringerAbstract:We demonstrate strong stimulated inelastic X-Ray scattering by resonantly eXciting a dense gas target of neon with femtosecond, high-intensity X-Ray pulses from an X-Ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic X-Ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered X-Ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic X-Ray scattering, with spectral resolution smaller than the natural width of the core-eXcited, intermediate state.
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atomic inner shell X Ray laser at 1 46 nanometres pumped by an X Ray free electron laser
Nature, 2012Co-Authors: Nina Rohringer, Christoph Bostedt, Duncan Ryan, R A London, Michael Purvis, F Albert, J Dunn, John D Bozek, A Graf, Randal M HillAbstract:A femtosecond, high-intensity atomic X-Ray laser with a photon energy of 849 electronvolts is produced in singly ionized neon by pumping using an X-Ray free-electron laser. Achieving lasing at increasingly shorter wavelengths is a long-standing goal. This paper demonstrates an X-Ray laser operating on an inner-shell transition in singly ionized neon — the first atomic laser in the 1 kiloelectronvolt regime. It is pumped by X-Ray free electron laser (XFEL) pulses from the Linac Coherent Light Source at the SLAC National Accelerator Laboratory in Menlo Park, California. The atomic laser's high-intensity, femtosecond X-Ray pulse emission has significantly improved wavelength stability, monochromaticity and temporal coherence compared with XFEL radiation. Atomic X-Ray lasers could have applications in high-resolution X-Ray spectroscopy and nonlinear X-Ray studies. Since the invention of the laser more than 50 years ago, scientists have striven to achieve amplification on atomic transitions of increasingly shorter wavelength1,2,3,4,5,6,7. The introduction of X-Ray free-electron lasers8,9,10 makes it possible to pump new atomic X-Ray lasers11,12,13 with ultrashort pulse duration, eXtreme spectral brightness and full temporal coherence. Here we describe the implementation of an X-Ray laser in the kiloelectronvolt energy regime, based on atomic population inversion and driven by rapid K-shell photo-ionization using pulses from an X-Ray free-electron laser. We established a population inversion of the Kα transition in singly ionized neon14 at 1.46 nanometres (corresponding to a photon energy of 849 electronvolts) in an elongated plasma column created by irradiation of a gas medium. We observed strong amplified spontaneous emission from the end of the eXcited plasma. This resulted in femtosecond-duration, high-intensity X-Ray pulses of much shorter wavelength and greater brilliance than achieved with previous atomic X-Ray lasers. Moreover, this scheme provides greatly increased wavelength stability, monochromaticity and improved temporal coherence by comparison with present-day X-Ray free-electron lasers. The atomic X-Ray lasers realized here may be useful for high-resolution spectroscopy and nonlinear X-Ray studies.
Christoph Bostedt - One of the best experts on this subject based on the ideXlab platform.
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ultrafast X Ray induced nuclear dynamics in diatomic molecules using femtosecond X Ray pump X Ray probe spectroscopy
Physical Review A, 2016Co-Authors: C S Lehmann, T Osipov, Daniel Rolles, Christoph Bostedt, Antonio Picon, A Rudenko, A Marinelli, Dooshaye Moonshiram, N BerrahAbstract:Citation: Lehmann, C. S., Picon, A., Bostedt, C., Rudenko, A., Marinelli, A., Moonshiram, D., . . . Southworth, S. H. (2016). Ultrafast X-Ray-induced nuclear dynamics in diatomic molecules using femtosecond X-Ray-pump-X-Ray-probe spectroscopy. Physical Review A, 94(1), 7. doi:10.1103/PhysRevA.94.013426
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stimulated electronic X Ray raman scattering
Physical Review Letters, 2013Co-Authors: Clemens Weninger, J.j. Rocca, Christoph Bostedt, Michael Purvis, Duncan P Ryan, Richard A London, J D Bozek, Alexander Graf, G V Brown, Nina RohringerAbstract:We demonstrate strong stimulated inelastic X-Ray scattering by resonantly eXciting a dense gas target of neon with femtosecond, high-intensity X-Ray pulses from an X-Ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic X-Ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered X-Ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic X-Ray scattering, with spectral resolution smaller than the natural width of the core-eXcited, intermediate state.
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atomic inner shell X Ray laser at 1 46 nanometres pumped by an X Ray free electron laser
Nature, 2012Co-Authors: Nina Rohringer, Christoph Bostedt, Duncan Ryan, R A London, Michael Purvis, F Albert, J Dunn, John D Bozek, A Graf, Randal M HillAbstract:A femtosecond, high-intensity atomic X-Ray laser with a photon energy of 849 electronvolts is produced in singly ionized neon by pumping using an X-Ray free-electron laser. Achieving lasing at increasingly shorter wavelengths is a long-standing goal. This paper demonstrates an X-Ray laser operating on an inner-shell transition in singly ionized neon — the first atomic laser in the 1 kiloelectronvolt regime. It is pumped by X-Ray free electron laser (XFEL) pulses from the Linac Coherent Light Source at the SLAC National Accelerator Laboratory in Menlo Park, California. The atomic laser's high-intensity, femtosecond X-Ray pulse emission has significantly improved wavelength stability, monochromaticity and temporal coherence compared with XFEL radiation. Atomic X-Ray lasers could have applications in high-resolution X-Ray spectroscopy and nonlinear X-Ray studies. Since the invention of the laser more than 50 years ago, scientists have striven to achieve amplification on atomic transitions of increasingly shorter wavelength1,2,3,4,5,6,7. The introduction of X-Ray free-electron lasers8,9,10 makes it possible to pump new atomic X-Ray lasers11,12,13 with ultrashort pulse duration, eXtreme spectral brightness and full temporal coherence. Here we describe the implementation of an X-Ray laser in the kiloelectronvolt energy regime, based on atomic population inversion and driven by rapid K-shell photo-ionization using pulses from an X-Ray free-electron laser. We established a population inversion of the Kα transition in singly ionized neon14 at 1.46 nanometres (corresponding to a photon energy of 849 electronvolts) in an elongated plasma column created by irradiation of a gas medium. We observed strong amplified spontaneous emission from the end of the eXcited plasma. This resulted in femtosecond-duration, high-intensity X-Ray pulses of much shorter wavelength and greater brilliance than achieved with previous atomic X-Ray lasers. Moreover, this scheme provides greatly increased wavelength stability, monochromaticity and improved temporal coherence by comparison with present-day X-Ray free-electron lasers. The atomic X-Ray lasers realized here may be useful for high-resolution spectroscopy and nonlinear X-Ray studies.
