Goniometer-based femtosecond crystallography with X-ray free electron lasers
Abstract not provided
Cohen, Aina E.↗
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Results for “FREE ELECTRON LASERS”
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Single-shot diffraction data from the Mimivirus particle using an X-ray free-electron laser
Free-electron lasers (FEL) hold the potential to revolutionize structural biology by producing X-ray pules short enough to outrun radiation damage, thus allowing imaging of biological samples without the limitation from radiation damage. Thus, a major part of the scientific case for the first FELs was three-dimensional (3D) reconstruction of non-crystalline biological objects. In a recent publication we demonstrated the first 3D reconstruction of a biological object from an X-ray FEL using this technique. The sample was the giant Mimivirus, which is one of the largest known viruses with a diameter of 450 nm. Here we present the dataset used for this successful reconstruction. Data-analysis methods for single-particle imaging at FELs are undergoing heavy development but data collection relies on very limited time available through a highly competitive proposal process. This dataset provides experimental data to the entire community and could boost algorithm development and provide a benchmark dataset for new algorithms.
59 BASIC BIOLOGICAL SCIENCES↗
Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser
Not Available
Higley, Daniel J.↗
Dispersion-Based Fresh-Slice Scheme for Free-Electron Lasers
The fresh-slice technique improved the performance of several self-amplified spontaneous emission free-electron laser schemes by granting selective control on the temporal lasing slice without spoiling the other electron bunch slices. So far, the implementation has required a special insertion device to create the beam yaw, called a dechirper. Finally, we demonstrate a novel scheme to enable fresh-slice operation based on electron energy chirp and orbit dispersion that can be implemented at any free-electron laser facility without additional hardware.
47 OTHER INSTRUMENTATION↗
Generating femtosecond X-ray pulses using an emittance-spoiling foil in free-electron lasers
Generation of femtosecond to sub-femtosecond pulses is attracting much attention in X-ray free-electron laser user community. One method is to use a slotted, emittance-spoiling foil which was proposed before (P. Emma et al., Phys. Rev. Lett. 92, 074801 (2004)) and has been widely used at the Linac Coherent Light Source. Direct experimental characterization of the slotted-foil performance was previously unfeasible due to a lack of appropriate diagnostics. With a recently installed X-band radio-frequency transverse deflector, we are able to characterize the electron bunch spoiling effect and X-ray pulse when using the slotted foil. We show that few-femtosecond X-ray pulses are generated with flexible control of the single-pulse duration or double-pulse separation with comparison to the theoretical model.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Generation and measurement of intense few-femtosecond superradiant extreme-ultraviolet free-electron laser pulses
Free-electron lasers producing ultrashort pulses with high peak power promise to extend ultrafast non-linear spectroscopic techniques into the extreme-ultraviolet–X-ray regime. Key aspects are the synchronization between pump and probe, and the control of the pulse properties (duration, intensity and coherence). Externally seeded free-electron lasers produce coherent pulses that can be synchronized with femtosecond accuracy. An important goal is to shorten the pulse duration, but the simple approach of shortening the seed is not sufficient because of the finite-gain bandwidth of the conversion process. An alternative is the amplification of a soliton in a multistage, superradiant cascade: here, we demonstrate the generation of few-femtosecond extreme-ultraviolet pulses, whose duration we measure by autocorrelation. Overall, we achieve pulses four times shorter, and with a higher peak power, than in the standard high-gain harmonic generation mode and we prove that the pulse duration matches the Fourier transform limit of the spectral intensity distribution.
36 MATERIALS SCIENCE↗
X -band rf driven free electron laser driver with optics linearization
Not Available
43 PARTICLE ACCELERATORS↗
Phase space manipulations for optimization of an inverse free electron laser
The Inverse Free Electron Laser (IFEL) has developed into a mature advanced accelerator with the ability to produce mono energetic high brightness beams accelerated at gradients beyond those of conventional RF technology. By copropagating a relativistic electron beam and a high power laser in a strongly tapered undulator, resonant energy exchange can be maintained over large distances. To optimize the number of electrons accelerated in an IFEL, one must prepare the initial electron beam phase space such that a majority of particles are injected at the accelerating phase of the ponderomotive potential. We present a scheme for optimization of the Rubicon IFEL accelerator trapping by preparing the initial electron beam phase space. Utilizing two cascaded modulator-chicane pre-bunchers simulations predict 95% capture of the injected electron beam.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Resolving indexing ambiguities in X-ray free-electron laser diffraction patterns
Abstract not provided
Uervirojnangkoorn, Monarin↗
Ultrafast nonthermal heating of water initiated by an X-ray Free-Electron Laser
Explore the source record for details and available documents.
99 GENERAL AND MISCELLANEOUS↗
Long range coherence in free electron lasers
The simple free electron laser (FEL) design uses a static, periodic, transverse magnetic field to undulate relativistic electrons traveling along its axis. This allows coupling to a co-propagating optical wave and results in bunching to produce coherent radiation. The advantages of the FEL are continuous tunability, operation at wavelengths ranging from centimeters to angstroms, and high efficiency resulting from the fact that the interaction region only contains light, relativistic electrons, and a magnetic field. Theoretical concepts and operational principles are discussed.
Colson, W. B.↗
A revised partiality model and post-refinement algorithm for X-ray free-electron laser data
An updated partiality model and post-refinement algorithm for XFEL snapshot diffraction data is presented and confirmed by observing anomalous density for S atoms at an X-ray wavelength of 1.3 Å. Research towards using X-ray free-electron laser (XFEL) data to solve structures using experimental phasing methods such as sulfur single-wavelength anomalous dispersion (SAD) has been hampered by shortcomings in the diffraction models for X-ray diffraction from FELs. Owing to errors in the orientation matrix and overly simple partiality models, researchers have required large numbers of images to converge to reliable estimates for the structure-factor amplitudes, which may not be feasible for all biological systems. Here, data for cytoplasmic polyhedrosis virus type 17 (CPV17) collected at 1.3 Å wavelength at the Linac Coherent Light Source (LCLS) are revisited. A previously published definition of a partiality model for reflections illuminated by self-amplified spontaneous emission (SASE) pulses is built upon, which defines a fraction between 0 and 1 based on the intersection of a reflection with a spread of Ewald spheres modelled by a super-Gaussian wavelength distribution in the X-ray beam. A method of post-refinement to refine the parameters of this model is suggested. This has generated a merged data set with an overall discrepancy (by calculating the R{sub split} value) of 3.15% to 1.46 Å resolution from a 7225-image data set. The atomic numbers of C, N and O atoms in the structure are distinguishable in the electron-density map. There are 13 S atoms within the 237 residues of CPV17, excluding the initial disordered methionine. These only possess 0.42 anomalous scattering electrons each at 1.3 Å wavelength, but the 12 that have single predominant positions are easily detectable in the anomalous difference Fourier map. It is hoped that these improvements will lead towards XFEL experimental phase determination and structure determination by sulfur SAD and will generally increase the utility of the method for difficult cases.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser
A new batch preparation method is presented for high-density micrometre-sized crystals of the G protein-coupled receptor rhodopsin for use in time-resolved serial femtosecond crystallography at an X-ray free-electron laser using a liquid jet. Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Brighter and faster: The promise and challenge of the x-ray free-electron laser
Starting with the Linac Coherent Light Source in 2009, free-electron lasers are using x rays in new ways. Early results are wowing scientists the world over.
43 PARTICLE ACCELERATORS↗
Circular dichroism measurements at an x-ray free-electron laser with polarization control
Not Available
Hartmann, G.↗
Demonstration of Single-Crystal Self-Seeded Two-Color X-Ray Free-Electron Lasers
A scheme for generating two simultaneous hard-x-ray free-electron laser pulses with a controllable difference in photon energy is described and then demonstrated using the self-seeding setup at the Linac Coherent Light Source (LCLS). The scheme takes advantage of the existing LCLS equipment, which allows two independent rotations of the self-seeding diamond crystal. The two degrees of freedom are used to select two nearby crystal reflections, causing two wavelengths to be present in the forward transmitted seeding x-ray pulse. The free-electron laser system must support amplification at both desired wavelengths.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Two-photon absorption of soft X-ray free electron laser radiation by graphite near the carbon K-absorption edge
We have examined the transmission of soft X-ray pulses from the FERMI free electron laser through carbon films of varying thickness, quantifying nonlinear effects of pulses above and below the carbon K-edge. At typical of soft X-ray free electron laser intensities, pulses exhibit linear absorption at photon energies above and below the K-edge, ~308 and ~260 eV, respectively; whereas two-photon absorption becomes significant slightly below the K-edge, ~284.2 eV. The measured two-photon absorption cross section at 284.18 eV (~6 x 10-48 cm4 s) is 7 orders of magnitude above what is expected from a simple theory based on hydrogen-like atoms - a result of resonance effects.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
A liquid jet setup for x-ray scattering experiments on complex liquids at free-electron laser sources
In this paper we describe a setup for x-ray scattering experiments on complex fluids using a liquid jet. The setup supports Small and Wide Angle X-ray Scattering (SAXS/WAXS) geometries. The jet is formed by a gas-dynamic virtual nozzle (GDVN) allowing for diameters ranging between 1 μm and 20 μm at a jet length of several hundred μm. To control jet properties such as jet length, diameter, or flow rate, the instrument is equipped with several diagnostic tools. Three microscopes are installed to quantify jet dimensions and stability in situ. The setup has been used at several beamlines performing both SAXS and WAXS experiments. As a typical example we show an experiment on a colloidal dispersion in a liquid jet at the X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source free-electron laser.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗