SwissFEL Workshop 2: Scattering and diffraction experiments
205 (University of Berne)
University of Berne
The SwissFEL team of the Paul Scherrer Institute invites you to the November workshop on hard X-ray instrumentation at the SwissFEL X-ray Free Electron Laser facility. The purpose of the workshop is to assist in the planning of the ARAMIS beamlines and experimental stations.
Workshop 2: November 21, 2011: Scattering and diffraction
Note: This is a workshop with only Poster presentations!
Goals of the Workshop:
1. Find out your requirements for optics at the ARAMIS beamline
2. Find out your requirements on the experimental infrastructure
From your Poster presentations we expect:
• new EXPERIMENTS!
• X-RAY PARAMETERS
• sketches of EXPERIMENTAL SETUP
• answer to questions from the Workshop Brochure page 8 and 9
• any other topics which are crucial
Please send us your Poster in A0 Format before the 10th of November (email: Stefanie.steinbrückner@psi.ch), so that we can print the posters and put them in the Posterbook that will be distributed at the workshop.
In order to have a maximum benefit from the workshop please read the workshop brochure, which you can download on the left side of this page.
For the presentation of your poster during the workshop, please prepare a short powerpoint presentation of 5 minutes.
Table Paramenter Requirements
Heinz J Weyer
J. Friso van der Veen
Jeroen van Bokhoven
Maria Isabel Ruiz Lopez
(Paul Scherrer Institut)
(Paul Scherrer Institut)
Coherent Control of Microscopic Order: High Field THz and Xray experiments at the SwissFEL
With the advent of electromagnetic radiation sources in the range from 0.1 to 10 THz, new ways to study fundamental physics phenomena have become accessible. THz sources capable of generating MV/cm transient electric field strengths are beginning to allow the investigation of nonlinear responses, and even coherent control, in a host of materials in a way not possible with other regions of the electromagnetic spectrum. Direct coherent control over collective excitations in systems where ultrafast changes in structure indicate rich physical processes could be insightfully studied with ultrafast Xray diffraction. The high intensity and time resolution of the proposed SwissFEL in tandem with single cycle, broadband THz pulses for non-resonant excitation or multiple cycle, narrowband THz radiation for resonant excitation would make the study of such phenomena possible. Great flexibility in bandwidth (from broadband to narrowband), polarization, and high field strength of the generated THz radiation are all central to the success of such experiments.
(PSI), MrSebastian Grübel
(PSI), MsTeresa Kubacka
Possibilities for nonlinear x-ray scattering with SwissFEL
The high peak spectral brilliance of SwissFEL will provide new opportunities to study the nonlinear interaction of x-rays with matter. for example, impulsive stimulated scattering can be used to control and manipulate coherent populations of material excitations with a flexibility not possible with nonlinear processes at optical wavelengths. This poster will discuss some of the required characteristics for such experiments at SwissFEL.
Theoretical calculations on ultrafast anisotropic X-ray scattering in the condensed phase
The advent of X-ray free electron lasers offers new opportunities for X-ray scattering studies of the ultrafast molecular dynamics in liquids, which was so far limited to the 100 ps resolution of synchrotrons. Photoselection induces anisotropy in the sample, which enhances the contrast of the signal from excited molecules against the diffuse background, while allowing probing of their vibrational and rotational dynamics. In this poster, we present a computational approach for calculating the transient scattering intensities of iodine in n-hexane, based on molecular dynamics simulations. We also derive, using realistic parameters the anticipated signal-to-noise ratio for a large class of diatomic elements in solution.
Ultrafast Structural Dynamics in Strongly Correlated Electron System: Timing Specifications
X-ray diffraction is a promising tool to study the subtle interaction of the atomic lattice with the electronic degrees of freedom (long range charge, orbital and spin order) in strongly correlated electron systems. We have recently shown [1,2] that photo-induced structural phase transitions (e.g. a change of structural symmetry) in these materials can occur on time scales significantly faster than 200 fs the current time resolution at the SLS-FEMTO beamline. Optical data on a magnetoresistive manganite indicate  that the relevant structural dynamics may occur on a time scale as fast as ~70 fs corresponding to the period of the Ag Jahn-Teller stretching mode of the oxygen octahedra. Also in  even faster dynamics were observed (30 THz) attributed to orbital waves. In order to resolve such dynamics in greater detail a time resolution of <20 fs (FWHM) is required. Currently only an FEL capable of generating x-ray significantly shorter than 5 fs can offer such a time resolution provided that the jitter between the ultrashort excitation pulses (derived from an optical laser) can be kept below 10 fs or, alternatively, be measured shot-to-shot with this accuracy. In addition the high FEL flux will offer access to many Bragg reflections. This together with the appropriate time resolution will permit disentangling the atomic motions within the unit cell and give fundamental new insights to what is responsible for this strong correlation between lattice and the electronic order in these materials.
 P. Beaud, S. L. Johnson, E. Vorobeva, U. Staub, R. A. De Souza, C. J. Milne, Q. X. Jia and G. Ingold, Phys. Rev. Lett. 103, 155702 (2009)
 . Möhr-Vorobeva, S. L. Johnson, P. Beaud, U. Staub, R. De Souza, C. Milne, G. Ingold, J. Demsar, H. Schaefer, and A. Titov, Phys. Rev. Lett. 107, 036403 (2011)
 . Polli, M. Rini, S. Wall, R. W. Schoenlein, Y. Tomioka, Y. Tokura, G. Cerullo, A. Cavalleri, Nature Mat. 6, 643 - 647 (2007).
Femtosecond analysis of protein nanocrystals and supramolecular complexes.
Membrane proteins (MPs) represent key components of cell membranes, about one fourth of the human proteome and 60% of the drug targets. We are interested in learning about the different conformations a MP can adopt in response to interacting molecules. The best way to analyse this at the atomic level is to determine their 3D-structure by crystal X-ray diffraction. We aim at producing nanocrystals of MPs and of supramolecular complexes, especially those related to tubulin, for analysis with FELs. A range of techniques will have to be employed for nanocrystal detection. Nanocrystals may exhibit fewer lattice imperfections compared to larger crystals. The x-ray beam parameters needed to analyse nanocrystals by “diffract-and-destroy” serial crystallography will be discussed as well as the way to deliver the nanocrystals to the beam.
CAMP: Flexible User End Station for Multidimensional Imaging Experiments at XFELs
During the last decade the rapid development of ultra-intense short-pulsed accelerator-based coherent X-ray light sources, Free-Electron Lasers (FEL), opened up a wide range of promising applications in physics, chemistry, biology and material sciences, in particular, paving the way towards imaging experiments with atomic spatial and fs temporal resolution. In order to enable these kind of studies, and to meet the requirements set by rapidly evolving interdisciplinary environment at FEL facilities, the Max Planck Advanced Study Group (ASG) at the Centre for Free Electron Laser Science (CFEL) has developed a multi-purpose experimental end station (CFEL-ASG Multi-Purpose chamber – CAMP) aimed at simultaneous (coincident) detection of ions, electrons, and (scattered or fluorescent) photons produced by the interaction of the FEL radiation with a large variety of targets (atoms, molecules, clusters, bio- and nano-particles, nano-crystas, solid-state samples etc.) .
The CAMP instrument is designed to host two unique large-area energy-resolving fast readout pnCCD detectors (developed by the Max Planck Semiconductor Laboratory) in combination with advanced many-particle electron and ion imaging systems (“reaction microscope” or double-sided velocity map imaging (VMI) spectrometers). After the commissioning of the first set of CAMP pnCCD detectors at the Free-electron LASer at Hamburg (FLASH) in August 2009, the whole machine was successfully installed at the Linac Coherent Light Source (LCLS) at Stanford, and hosted more than 20 user experiments during the first two years of LCLS operation, including, among others, multi-parameter studies on multiple ionization of atoms , photoelectron spectroscopy from laser-aligned molecules, (time-resolved) single-shot measurements on single clusters, coherent diffractive imaging of nano-crystals  and gas-phase viruses , nano-scale morphometry and mass spectrometry of aerosols , experiments with solid-state targets  etc.
With its leading-edge photon detectors, unique capabilities for multi-coincident measurements, and being adapted to host many of the sample delivery systems currently used or being developed within the active FEL community, this type of end station offers a variety of exciting experimental possibilities at different XFEL facilities. Currently a copy of this setup is being commissioned at the Spring 8 Angstrom Compact free-electron LAser (SACLA) in Japan, whereas the original CAMP apparatus is planned to be permanently installed at FLASH after it will be replaced by the slightly modified LAMP (LCLS-ASG Multi-Purpose) instrument at LCLS. Similar multi-parameter end station, as well as its individual components might become a valuable complementation for the user instrumentation at the upcoming SwissFEL.
 L. Strüder et al., Nucl. Instr. Meth. 614 483 (2010).
 B. Rudek et al., Nature Physics, submitted
 H.N. Chapman et al., Nature 470 73 (2011).
 M.M. Seibert et. al., Nature 470 78 (2011).
 N.D. Loh et. al., Science, submitted.
 S. Hau-Riege et al., Nature Materials, submitted
(Max Planck Advanced Study Group at CFEL)
Table-top Soft X-ray Laser in the X-ray Free-Electron Laser Era
Newly available light sources are pushing the limit of insights thanks to short wavelength light sources. Most of these large-scale sources, such as the X-ray Free-Electron Laser as well as the Synchrotron, are operated as user-facilities, i.e. the researchers can access them on a beam-time basis, in shifts of a few hours each. Therefore, despite the superior performance of such instrumentation, and uniqueness for proof-of-principle investigations, their footprint, cost, and bottlenecked access represent major impedances to scientific throughput. Furthermore, the interface with the industry is hampered, which slows-down the rapid porting of cutting-edge fundamental findings into products for the society.
The Bern Advanced Glass Laser for Experiments (“BeAGLE”) is our table-top system for the generation of coherent light in the extreme ultraviolet (XUV). Its uniqueness resides in the unmatched narrow linewidths (<0.01%), discrete tunability across the XUV, redundant brightness of >1025 ph. s-1 mm-2 mr-2 0.1% BW-1, and compactness. The performance of the XUV laser is complementary to that of high-harmonic generation (HHG), which with its broadband emission is superior for the generation of sub-fs pulses, thus in fact enabling atto-science. On the other hand, the mentioned specifications make the XUV laser ideal for a number of ultrafast imaging and spectroscopy applications. These are nowadays widely popular at large-scale facilities, and it is a preliminary research task of my group that of enabling comparable nano-science capabilities in the lab.
Inferring Networks from Distances: the "Landscape" of Glycosidase Protein Structures
Multidimensional high energy spectroscopy in X-rays/electron hybrid experiments
We propose an experiment in which a beam of pulsed X-rays is combined to a pulsed electron beam in a Transmission Electron Microscope. Thanks to such an apparatus, X-ray chemically selective photo-doping of materials can be obtained while its effect can be investigated in diffraction, imaging or spectroscopy in a TEM. Recent development in pulsed electron sources allow a temporal resolution comparable to that achievable with light beams, and the combination of these tools can open fascinating new areas of investigation.
Dynamics of the ion diffusion in clays: a proposed probe-probe XPCS experiment
S.V. Churakov1, R. Dähn1, A. Froideval1, B. Pedrini2
1Nuclear Energy and Safety (NES), Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
2SwissFEL Project, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
Clay rich argillaceous rocks are foreseen as natural barriers in many disposal concepts worldwide for environmental protection of radioactive and toxic waste due to their low hydraulic conductivity. The slow migration of pollutants in engineered barriers arises from stochastic motion of cations in the interlayer of clay minerals. An in-depth understanding of the ion diffusion processes in the interlayer of clay minerals, which size is on the order of 1 nm is indispensable for the long term prediction of safety assessments of waste repositories. To date, such processes which occur at time scales ranging from ~10 - 100 ps are accessible only via molecular dynamics simulations . To increase our confidence in numerical models the theoretical calculations of Na, Cs and H2O transport in the interlayer of clays need to be experimentally verified. Water dynamics in nanoporous material and clays is readily probed in neutron scattering experiments . To our best knowledge, a direct measurement of Cs or Na diffusion in the interlayer of clays is not possible at present experimental infrastructure.
Therefore, the ionic transport in the interlayer space of clay minerals is here proposed to be investigated by performing split-pulse X-ray photon correlation spectroscopy (XPCS) measurements of q-dependence correlation times , for X-ray FEL pulses separated in time by 10 ps. Such experiments could possibly help (i) to measure the ionic mobility, and (ii) to understand the ion transport mechanism(s) in the interlayer namely Brownian versus non-Brownian diffusion.
The ability of synchrotron-based measurements to obtain a quantitative understanding of the dynamics of disorder in alloys has already been reported in the literature [4, 5]. From their work, Leitner et al. have been able to probe the so far inaccessible atomic-scale diffusion parameter such as the bulk diffusivity of a single atom in a short-range ordered single crystal Cu90Au10 alloy, proving the ability of the XPCS technique to study dynamics of disorder in well-ordered materials. Such results lend strong support to FEL-based XPCS experiments in order to quantify the mobility of the interlayer molecular species in clay minerals at ps and even sub-ps time scales. It is estimated that a single X-ray FEL pulse (containing 1011 hard X-ray photons – with an X-ray energy of 12.4 keV (i.e. a X-ray wavelength of 1 Å) – focused into a 100 100 nm2 spot, will yield a resolution of approximately 3 nm. Under such experimental conditions, the scattering intensity, by e.g. ~1028 Cs atoms located in a montmorillonite sample, is predicted to be close to 1 scattered photon per pixel, for small values of scattering angles in the range 0–2° ; such a number of detected scattered photons being probably compatible with the high performances of the PILATUS detector . Note that these calculations are done for a 10 µm-thick montmorillonite sample and a Cs concentration of 1.25 Cs atoms.nm-3. A better understanding of the dependence of atomistic quantities such as e.g. diffusion activation energies on the local atomic structure could thus be gained by taking advantage of the full coherence of the XFEL radiation. Furthermore, such novel quantitative information on the diffusion mobility of the interlayer species in clay materials will serve as experimental input to assist the development of robust geochemical databases on diffusion processes in clay systems for performance assessments of the clay barrier in the deep geological disposal of radioactive waste.
 G. Kosakowski, S.V. Churakov, T. Thoenen, Clays Clay Miner. 56 (2008) 190-206.
 F. González Sánchez, F. Jurányi, T. Gimmi, L. Van Loon, T. Unruh, and L. W. Diamond, J. Chem. Phys. 129 (2008) 174706.
 G. Grübel, G.B. Stephenson, C. Gutt, H. Sinn, Th. Tschentscher, Nucl. Instr. and Meth. in Phys. Res. B 262 (2007) 357-367.
 M. Leitner, B. Sepiol, L.-M. Stadler, B. Pfau, G. Vogl, Nat. Mater. 8 (2009) 717-720.
 S. Brauer, G.B. Stephenson, M. Sutton, R. Brüning, E. Dufresne, S.G.J. Mochrie, G. Grübel, J. Als-Nielsen, D.L. Abernathy, Phys. Rev. Lett. 74 (1995) 2010-2013.
 A. Froideval, A. Badillo, J. Bertsch, S. Churakov, R. Dähn, C. Degueldre, T. Lind, D. Paladino, B.D. Patterson, J. Nucl. Mater. 416 (2011) 242-251.
 F. Westermeier, T. Autenrieth, C. Gutt, O. Leupold, A. Duri, A. Menzel, I. Johnson, C. Broennimann, G. Grübel, J. Synchrot. Rad. 16 (2009) 687-689.
2D Membrane Protein Crystal Diffraction
Authors: Ching-Ju Tsai1, Bill Pedrini2, Cameron M. Kewish3, Bruce D. Patterson2, Rafael Abela2, Gebhard Schertler1, Xiao-Dan Li1
1Laboratory of Biomolecular Research and 2SwissFEL Project, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
3Synchrotron Soleil, L’ Orme des Merisiers, BP 48 Saint Aubin, 91192 Gif-sur-Yvette cedex, France
Most of the known protein structures have been determined by synchrotron source X-ray crystallography, which requires macroscopic crystals of larger than 1m in size to overcome radiation damage and achieve subnanometer resolution. Obtaining well-ordered crystals of such size can be challenging, time-consuming, expensive and in many cases impossible. Three dimensional (3D) nanocrystals and two-dimensional (2D) crystals of membrane proteins can be obtained, which are an important class of drug targets. However, such samples do not provide sufficient signal intensity in synchrotron experiments. With the advent of Free Electron Lasers (FELs), it has become possible to collect a large number of diffraction images from many samples in the so called "diffract and destroy mode". Chapman and collaborators  have shown first results using Photosystem I 3D nanocrystals, which were injected into the X-ray beam with a liquid mother liquor jet. Here we discuss a similar experiment using micrometer sized 2D membrane protein crystals. Sample refreshing is achieved by scanning the sample to diffract the incoming X-ray beam at a different, undamaged position each time. The main issues for the experiment are the positioning of the sample at a scale smaller than the typical size of a crystal, and a sufficient incoming X-ray photon flux, as is always the case when the number of diffracting atoms is reduced. It has also been suggested that the full transverse coherence will the 2D crystallographic phase problem to be solved iteratively , for which the achievement of a submicrometer focus will be of critical importance.
 H. N. Chapman et al., Nature 470, 73-78 (2011)
 C. M. Kewish et al., New J. Phys 12, 035005 (2010)
Terahertz Streak Camera as Arrival Time Monitor for SwissFEL
The SwissFEL design expects to provide users with X-ray pulses of few-femtosecond duration, which will be synchronized to a pump / probe laser. At present, no device exists to measure the relative arrival time and the X-ray pulse length with the required precision. We propose here the development of a Terahertz streak camera as photon arrival time and pulse length monitor (PALM). The efforts will be based on existing skills and capabilities in the GFA Diagnostics Section and the SwissFEL Laser Group. Commissioning and calibration of the PAM will be performed at the seed laser in the SwissFEL Injector Test Facility. The successful execution of this research proposal will enable the applicants to design a photon arrival time and pulse length monitor for SwissFEL.
(Paul Scherrer Institut)
Diffractive optics for focusing and characterization of hard X-ray free electron laser radiation
The unique characteristics of the hard XFEL radiation impose new requirements for the focusing optics used when compared to hard synchrotron radiation. For example the heat loads caused by the extremely high photon flux quickly damage conventional optics such as Fresnel zone plates (FZPs) or diffraction gratings. Here we present results obtained using nanostructures based on diamond at Linac Coherent Light Source (LCLS). The focusing properties of diamond FZPs were measured using the imprint technique. The spot size was observed to be limited by the spectral bandwidth of the source to 320 nm FWHM. Also, a spectrometer setup based on a focusing diamond grating is presented with measured shot-to-shot spectra of LCLS beam.
(Paul Scherrer Institut)
Dynamics of irradiation-induced defects in nuclear materials: a proposed ion pump - X-ray FEL probe experimental approach
The radiation tolerance of materials in nuclear reactors is an important issue for the safe operation of current and future advanced nuclear plants. During reactor operation, irradiation-induced defects can form in nuclear reactor components such as fuels, fuel claddings (Zr-alloys), and (advanced) reactor pressure vessels. The nuclear materials of concern represent steels, ceramics, composite materials, and graphite used in high temperature reactors (HTR). The fundamental origin of irradiation damage can be investigated using molecular dynamics simulations . However, no real-time measurement has so far been reported in the literature.
A «pump-probe» coherent scattering experiment is thus proposed: the process could be triggered by a synchronized high energy ion (the pump), the probe consisting of diffuse scattering of the X-ray FEL pulse [2, 3]. Such an experimental methodology would determine statistical features of the material’s structure development of irradiation cascades directly after their initiation, and their dependence on e.g. the nature and the energy of the incident particles. The statistical nature of the formation of the primary interstitial and vacancy defects and their nanometer-sized clusters leading to dislocation loops, and precipitates, as well as the evolution of their structure, distribution, and mobility, should in principle be accessible on a time scale of ~ 0.1-100 ps. The average size and density of the central vacancy cluster and the diffusion rate of the defect clusters should be obtained through correlation analysis of scattering. Such time-resolved X-ray diffuse scattering experiments could help to gain deeper insight into the cascade dynamics and defect evolution at early stages in nuclear materials. Moreover, such experimental results will then be compared to molecular dynamics simulations, allowing the experimental validation of the simulation methods, as well as a better understanding of the materials’ resistance to particle irradiation.
 F. Devynck and M. Krack, "Dynamics of irradiation-induced defects in nuclear materials: a proposed ion pump - X-ray FEL probe experimental approach", contribution to the Workshop on Petawatt Lasers at Hard X-Ray Light Sources, Dresden-Rossendorf, September 5-9, 2011 (http://www.hzdr.de/db/Cms?pNid=2362).
 B. D. Patterson (Ed.), Ultrafast Phenomena at the Nanoscale: Science Opportunities at the SwissFEL X-Ray Laser, PSI Report Nr. 09-10, 2009.
 A. Froideval, A. Badillo, J. Bertsch, S. Churakov, R. Dähn, C. Degueldre, T. Lind, D. Paladino, B. D. Patterson, Journal of Nuclear Materials, 416 (2011) 242-251.
(Paul Scherrer Institute / Nuclear Energy and Safety)
Influence of gelation kinetics by microwaves
In the PINE project, nuclear fuel microspheres are obtained by microwave internal gelation (MIG) [1, 2]. Free falling droplets, containing chemical ingredients (feed solution), undergo a precipitation (gelation) induced by microwave heating. The reaction is triggered by decomposing a reactant at a given temperature. However, literature suggests that microwaves could also have a nonthermal catalityc effect on chemical reactions [3, 4, 5]. In order to understand and improve the process, the degree of gelation advancement inside the falling droplet needs to be determined. This can be done thanks to a XAS measurement of droplets at different gelation states. An experiment at the SuperXAS beamline (PSI) has proven that falling drops could be detected and analysed.
The high time resolution of the swissFEL allows the determination of effects faster than thermalisation (thermalisation time ~1 ps), for example by single shot (pulse length 13-16 fs) EXAFS (XANES) spectra on the metal absorber (cerium). The possibility to extract whole spectra from single exposures also allows to perform above experiment (at SuperXAS) on single droplets, and provides much better spectra, as changing droplet characteristics are omitted. Using a beam splitter, or delay lines based on diffractive X-ray optics (idea by C. David , PSI LMN), a multiple pulse (ideally 4 to 10) can be produced in the time range of a microwave period (100 ps at 10 GHz). This tool provides a temporal mapping of the surrounding species and resolves the influence of the EM electro-magnetic field on their interaction. It will provide essential information on the nonthermal microwave enhancement of chemical reactions.
 M. Pouchon and collaborators. Pine - platform for innovative nuclear fuels. Technical report, CCEM, Annual activity reports 2009, 35-36.
 M.A. Pouchon and collaborators. Pine - platform for innovative nuclear fuels. Technical report, CCEM, Annual activity reports 2010, 42-44.
 J. Berlan. Microwaves in chemistry: another way of heating reaction mixtures. Radiat. Phys. Chem., 45:581–589, 1995.
 J.H. Booske, R.F. Cooper, and S.A. Freeman. Microwave enhanced reaction kinetics and ceramics.pdf. Mat. Res. Innovat., 1:77–84, 1997.
 B. Toukoniitty, J.-P. Mikkola, D. Y. Murzin, and T. Salmi. Utilization of electromagnetic and accoustic irradiation in enhancing heterogeneous catalytic reactions. Applied Catalysis A, 279:1–22, 2005.
 C. David. PSI-XFEL Workshop, Villigen, February 26-27, 2009.
(Paul Scherrer Institut)
Probing magnetic phase transitions
Manipulation of magnetic materials induced by single laser pulses include changing the magnetic order and domain dynamics on a sub-ps time scale. In the presence of a first order phase transition, stimulated phase competition is a promising route to study the coupled dynamics of magnetic, orbital and structural order. Time-, element- and spatially resolved X-ray magnetic scattering (TR-XRMS) allows to disentangle in the time domain the relevant interactions such as Coloumb, exchange, spin-orbit and electron-phonon interactions. In the new transient phase, the coexistence of AFM and FM order as well as the correlation length (size) of the FM domains are of interest . Microscopically, the channels for energy, momentum and angular momentum transfer between orbital, spin and lattice degress of freedom have to be understood. A fertile area are crystalline multiferroic solids (such as perovskite transition
metal oxides and Heusler alloys) where the magnetization, polarization and stress are generally sensitive to an abrupt change of lattice parameters (and vice versa) and where the reversibility of phase transformations may have profound technological implications. For experiments at SwissFEL we need tunable X-ray energies to reach relevant K- and L-edges of transition metals and rare earth elements , flexible polarization of both the pump and probe beams , and a phase front preserving sample environment to exploit the full transverse coherence of the X-ray beam . The endstation must allow for a flexible sample environment (in terms of temperature, electric & magnetic fields and pressure) and most likely will have to incorporate X-ray timing diagnostics to perform pump-probe experiments with time resolution 10 fs in a repeatable and reliable fashion.
 S.O.Mariager et al. To be pulished.
 B.J.Kim et al. Science 323 (2009) 1329.
 U.Staub et al. Phys. Rev. B 82 (2010) 104411.
 O.G.Shpyrko et al. Nature 447 (2007) 68.
Vibrational control of quantum materials: ultrafast x-ray diffraction studies
Transition metal oxides exhibit functional electronic properties still waiting to be fully exploited in real-word applications. An important step toward the practical use of quantum materials is to achieve on-demand control of their ground state. An innovative strategy is based on the use of light pulses in the mid infrared and THz range to initiate lattice dynamics and to substantially perturb the electronic properties of a solid. Strong vibrational excitation  is indeed capable of inducing electronic phase transitions, as demonstrated in a recent series of experiments on cuprates  and manganites  where transient superconductivity and metallicity were triggered.
In this contribution we will discuss the requirements for ultrafast x-ray diffraction experiments aimed at elucidating the evolution of the crystal lattice as transient electronic phases are induced by vibrational excitation.
 M. Först et al., Nat. Phys. doi: 10.1038/NPHYS2055.
 D. Fausti, R.I. Tobey, N. Dean, S. Kaiser, A. Dienst, M.C. Hoffmann, S. Pyon, T. Takayama, H. Takagi, A. Cavalleri Science 331, 189 (2011).
 M. Rini, R. Tobey, N. Dean, J. Itatani, Y. Tomioka, Y. Tokura, R. W. Schoenlein, A. Cavalleri Nature 449, 72 (2007).
(Max Planck Research Department for Structural Dynamics, University of Hamburg)
Serial Femtosecond Crystallography at the SwissFEL X-Ray Free Electron Laser
We describe the possibility of performing serial femtosecond crystallography experiments at the SwissFEL X-Ray Free Electron Laser (FEL).
Single crystal X-ray diffraction snapshots can be collected from a stream of microcrystals flowing in a water jet using femtosecond pulses from a hard X-ray FEL (1).
Diffraction from ultra-short (<70 fs) pulses can be collected before significant changes occur to the sample (2). The recorded diffraction patterns can be indexed and merged in order to get accurate structure factors and then to calculate the electron density map (3). Serial crystallography can therefore be a novel way to determine the structure of proteins that do not grow into crystals of sufficient size for standard synchrotron radiation measurements or are particularly sensitive to radiation damage.
Serial crystallography also opens up the possibility for time resolved structural studies of irreversible processes. Optical pump lasers synchronized to FEL pulses (4) can be used to obtain X-ray diffraction snapshots from the excited states of proteins in nanocrystals, thus allowing the study of reaction dynamics in biological systems.
In the poster we show that these experiments can be performed at SwissFEL X-Ray FEL and we give details on beam, detectors and sample environment requirements.
1. H.N.Chapman et al. - Nature 470, 73 (2011)
2. A.Barty et al. - Nature Photonics (2011)
3. U. Weierstall, R. B. Doak, and J. C. H. Spence. Rev. Sci. Instr. Submitted (http://arxiv.org/abs/1105.2104)(2011)
4. R. A. Kirian et al. Acta Cryst A 67, 131 (2011)
(CFEL - DESY)
Time-resolved diffuse X-ray scattering
The relaxation of hot carriers through phonon interactions plays a crucial role in the physics of many highly interesting condensed matter systems, ranging from photovoltaic cells to strongly correlated systems exhibiting phenomena like superconductivity and charge density waves.
The experimental methods employed today to study phonon processes in these systems, however, either lack the time or the momentum resolution necessary to provide a comprehensive picture of the nonequilibrium phonon dynamics.
The combination of atomic scale wavelength, high photon flux and femtosecond duration of the SwissFEL X-ray pulses will make time-resolved tracking of the occupation of individual phonon branches throughout the whole Brillouin zone possible by recording two-dimensional diffuse scattering images following photoexcitation with a femtosecond laser pulse.
Bragg Coherent Diffractive Imaging at an XFEL
Materials with nanocrystalline morphology demonstrate vastly different properties in comparison to the bulk due to the strong influence of their surfaces, interfaces and defects. Understanding the strain present in these materials is required in order to tailor devices from them with desired properties.
Bragg coherent diffractive imaging (BCDI) is a rapidly developing non-destructive technique for the mapping of strain in crystalline materials. BCDI is sensitive to sub-Angstrom lattice distortions in crystals. The diffraction local to each bragg peak describes the displacement of the average lattice along the Q-vector direction of the chosen peak. The combination of multiple bragg peaks allows the determination of the full strain tensor. At synchrotron sources, the minimum size of individual crystals is limited to approx. 100nm, and the ability to probe environmental degrees of freedom in-situ as a function of time is limited to reversible processes in a binary state or irreversible processes on the timescale of days.
The increased flux available at an XFEL offers the opportunity to extend BCDI to sub 100nm grain sizes with improved spatial resolution. The 100Hz operating frequency allows one to contemplate probing reversible processes on the ultrafast timescale, in pump-probe mode, and irreversible processes on the timescale of several minutes. The technical requirements for BCDI in the aforementioned experimental regimes will be described.
(Paul Scherrer Institut)
Electron Cryo-microscopy and tomography of eukaryotic cilia/flagella
Our main focus is structural biology of eukaryotic flagella/cilia using electron cryo tomography and microscopy (cryo-EM). Cryo-EM provides images of biological macromolecules and organelles in their intact hydrated states.
The biological material in solution is spread on an EM grid and is preserved in a frozen-hydrated state by quick plunge freezing in liquid ethane at liquid nitrogen temperature. By maintaining specimens at liquid nitrogen temperature, they are then transferred into the high vacuum of the electron microscope column. Biological specimens are extremely radiation sensitive, so they must be imaged with low-dose techniques.
Since the images are extremely noisy, computational image analysis must be used to enable three-dimensional reconstruction. For highly symmetrical objects (2D crystal of membrane proteins, tubular crystals, icosahedral viruses) atomic resolution could be reached. For some biological systems it is possible to extract images of identical structures, align and average them to increase the signal-to-noise ratio and retrieve high-resolution information using the technique known as single particle analysis. This approach requires that the things being averaged are identical (some limited conformational heterogeneity can investigated by image classification). With this technique 3D reconstructions from cryo-EM images of protein complexes and viruses have been solved near-atomic resolution. In electron cryo-tomography images are acquired multiple times from an ice-embedded specimen tilted continuously in the microscope and merged into a 3D structure. This is a suitable method to analyze macromolecules forming complex and dynamic molecular networks in vivo. If there are identical structures in tomograms, these volumes can be extracted (subtomograms) and averaged to improve signal-to-noise ratio.
We apply these methods to reveal the mechanism of flagellar/ciliary bending motion in eukaryotes. In flagella/cilia, which consist of ~600 proteins, nine microtubule doublets are linked by dynein motor proteins. The activity of these motors is regulated by mechano-chemical interactions between a central pair of microtubules and big radial complexes of proteins (radial spokes), which are anchored to the nine-microtubule doublet. We revealed molecular arrangement of dynein, radial spokes, and other proteins by electron tomography and refine high-resolution structures by single particle analysis.
(Paul Scherrer Institut)
Serial Femtosecond Crystallography on tiny 3D crystals
The elucidation of structures of macromolecules is an important step in the quest of understanding the chemical mechanisms underlying biological function. X-ray crystallography is a mature method that is only limited by the quality of the crystals investigated and by radiation damage. Intense, femtosecond X-ray pulses provided by X-ray free-electron lasers promise to break the nexus between radiation damage and crystal size, thereby allowing structure determination using nano- and microcrystals. Recent serial femtosecond crystallography (SFX) experiments at the LCLS have shown the feasibility of this approach . A continuous liquid microjet was used to inject randomly oriented crystals with a flow rate of ~ 10 microl/min into the FEL beam [2,3]. The diffraction patterns were collected in vacuum at the repetition rate of the FEL in the CAMP  or CXI instruments  using pnCCD or CSPAD detectors, respectively. Due to the mismatch between continuous sample flow and stroboscopic data collection, sample consumption is huge. FEL-triggered drop-on-demand approaches have been proposed and are being explored . For very precious samples, other possibilities need to be explored which include preparation on fixed targets and cryo-stages, which are ideally integrated into dedicated endstations with appropriate detectors. Since the crystals intersect the FEL beam very fleetingly, only thin slices through the rocking curve are recorded, requiring many measurements of the reflections to allow a Monte-Carlo like integration of the beam profiles [6,7]. A pink or Laue beam has not only more flux than a monochromatic beam but is also more efficient in sampling reciprocal space. A shot-to-shot analysis of the spectrum would be highly desirable, for example to allow accurate profile fitting including coherent diffraction features as would be the availability of a divergent beam that can be matched to the sample size.
1. Chapman, H. N. et al. Femtosecond X-ray protein nanocrystallography. Nature 470, 73-77 (2011).
2. DePonte, D. P. et al. Gas dynamic virtual nozzle for generation of microscopic droplet streams. J. Phys. D: Appl. Phys. 41, 195505 (2008).
3. Weierstall, U., Doak, R.B., Spence, J.C.H. A pump-probe XFEL particle injector for hydrated samples. arXiv:1105.2104v1 [physics.ins-det] (2011)
4. Strueder, L. et al. Large-format, high-speed, X-ray pnCCDs combined with electron and ion imaging spectrometers in a multipurpose chamber for experiments at 4th generation light sources. Nuclear Instruments and Methods in Physics Research A 614, 483-496 (2010).
5. Boutet, S. and Williams G. J. The Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) New Journal of Physics 12, 035024 (2010)
6. Kirian, R. A. Femtosecond protein nanocrystallography-data analysis methods. Optics Express 18, 5713-5723 (2010).
7. Kirian, R. A. et al. Structure-factor analysis of femtosecond microdiffraction patterns from protein nanocrystals Acta Crystallogr. A 67, 131-140 (2011)
(Max-Planck-Institut fuer medizinische Forschung)
Energetics and Solvation Dynamics of the excited Ru(bpy)3 complex in water
(Institute of Physical Chemistry, University of Basel)