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  • richardmitnick 9:16 am on February 5, 2016 Permalink | Reply
    Tags: , , SLAC LCLS,   

    From DESY: “Scientists film exploding nanoparticles” 

    DESY
    DESY

    2016/02/05
    No writer credit found

    Imaging nanoscale dynamics with unparalleled detail and speed

    Using a super X-ray microscope, an international research team has “filmed” the explosion of single nanoparticles. The team led by Tais Gorkhover from Technische Universität Berlin, currently working at the SLAC National Accelerator Laboratory in the U.S. as a fellow of the Volkswagen Foundation, and Christoph Bostedt from the Argonne National Laboratory and Northwestern University has managed to combine a temporal resolution of 100 femtoseconds and a spatial resolution of eight nanometres for the first time. A nanometre is a billionth of a metre, and a femtosecond is a mere quadrillionth of a second. For their experiments, the scientists used the so-called free-electron X-ray laser LCLS.

    SLAC LCLS Inside
    LCLS at SLAC

    The exposure time of the individual images was so short that the rapidly moving particles in the gas phase appeared frozen in time. Therefore, they did not have to be fixed on substrates as it is commonly done in other microscopy approaches. The team, including researchers from the Center for Free-Electron Laser Science CFEL at DESY, reports its results in the scientific journal Nature Photonics.

    Xenon nanoparticle exploding
    Three states of an exploding xenon nanoparticle. The ultra short flashes of the X-ray laser record these states as a so-called diffraction pattern. From these, the state of the sample can be calculated. Credit: Tais Gorkhover/SLAC

    Most imaging approaches are severely limited when a combination of high spatial resolution and extreme shutter speed is required. Ultrafast optical approaches have a rather coarse resolution due to the long wavelength. Conversely, electron microscopy can yield ultrahigh resolution but demands a rather long exposure time and it requires the particles being fixed to substrates. Therefore ultrafast processes in free nanometre-sized particles cannot be directly imaged with conventional methods. However, the ability to image and understand the dynamics in nanostructures and aggregates is of relevance in many fields, ranging from climate models to nanotechnology.

    The properties and dynamics of nanoparticles can significantly change when they are deposited on a substrate. To avoid any modification, the particles, made of frozen xenon and with a diameter of around 40 nanometres, were imaged during their flight through a vacuum chamber. “Using the intense light of an infrared laser, the nanoparticles where superheated and exploded,” explains DESY scientist Jochen Küpper, who is also a professor at the University of Hamburg and a member of the Hamburg Centre for Ultrafast Imaging (CUI). The explosion was imaged with ultrafast X-ray flashes at different time steps. Küpper’s group helped to implement this so-called pump-probe technique. “The experiment was repeated over and over with a new nanoparticle every time and slightly increased delay of the X-ray flash,” reports Lotte Holmegaard from Küpper’s CFEL group. Subsequently the images were assembled to a „movie“.

    „To our big surprise the exploding particles appeared to be shrinking with time instead of expanding as intuitively expected“ says Gorkhover. This unexpected result could be explained with theoretical models that describe the explosion as a melting process starting on the surface instead of a homogenous expansion. In this process, the solid part of the particle’s core gets smaller and smaller what causes the illusion of a shrinking particle.

    Another very interesting aspect of this new imaging approach is that it is possible to directly image the dynamics in single, free nanoparticles. Most time resolved studies are based on ensembles of many particles and averaging statements in which some important differences such as size and shapes of the particles get lost. “We have already demonstrated the importance to look at one particle at a time in earlier static experiments. Now this approach is also available for time-resolved studies,” says Gorkhover.

    “Our experiments yield unprecedented insight into the non-equilibrium physics of superheated nanoparticles. Moreover, they open the door for a multitude of new experiments where the ultrafast dynamics of small samples is important.“ explains Bostedt. Such dynamics may be of relevance in the formation of aerosols which are of major importance in climate models as they are in a large part responsible for absorption and reflection of sunlight. They may also be interesting for research on laser driven fusion in small targets or the rapidly developing area of nanoplasmonics in which the properties of nanoparticles are manipulated with intense light fields.

    Reference:
    Femtosecond and nanometre visualization of structural dynamics in superheated nanoparticles; Tais Gorkhover, Christoph Bostedt et al.; „Nature Photonics“, 2016; DOI: 10.1038/NPHOTON.2015.264

    See the full article here .

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    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 5:21 pm on January 29, 2016 Permalink | Reply
    Tags: , SLAC LCLS,   

    From SLAC: “Tiniest Particles Shrink Before Exploding When Hit With SLAC’s X-ray Laser” 


    SLAC Lab

    January 29, 2016

    nanometer-sized clusters of xenon atoms (center) first shrink before exploding after being hit with very intense X-rays. In the experiment at LCLS
    Nanometer-sized clusters of xenon atoms (center) first shrink before exploding after being hit with very intense X-rays at LCLS.

    SLAC Experimental setup at LCLS used to determine that nanometer-sized particles first shrink before exploding after being hit with very intense X-rays.
    Experimental setup at LCLS used to determine that nanometer-sized particles first shrink before exploding after being hit with very intense X-rays. The researchers exposed tiny xenon clusters (injected from top left) to two consecutive X-ray pulses (green and red wavelets coming in from bottom left). The first pulse rapidly heats the cluster, while the second pulse probes how its structure changes over a period of 80 quadrillionths of a second. The structural changes are tracked with an X-ray detector (right). (SLAC National Accelerator Laboratory)

    Researchers assumed that tiny objects would instantly blow up when hit by extremely intense light from the world’s most powerful X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory. But to their astonishment, these nanoparticles initially shrank instead – a finding that provides a glimpse of the unusual world of superheated nanomaterials that could eventually also help scientists further develop X-ray techniques for taking atomic images of individual molecules.

    The experiments took place at the Linac Coherent Light Source (LCLS) X-ray laser, a DOE Office of Science User Facility. Its pulses are so bright that they can be used to turn solids into highly ionized gases, or plasmas, that blow up within a fraction of a second. Fortunately, for many samples researchers can take the data they need before the damage sets in – an approach that has been used to reveal never-before-seen details of a variety of samples relevant to chemistry, materials science, biology and energy research.

    The ultimate limits of this approach are, however, not well understood. One of the key visions for X-ray laser science is to image individual, one-of-a-kind particles with single X-ray pulses. To do so in a quantitative manner, researchers need to understand precisely how each molecule responds to the intense X-ray light. The new study, published today in Science Advances, provides an unexpected insight into this aspect.

    “So far, all models have assumed that a very small system would immediately explode when we pump a lot of energy into it with the X-ray laser,” says former LCLS researcher Christoph Bostedt, who is now at Argonne National Laboratory and Northwestern University. “But our experiments showed otherwise.”

    At LCLS, Bostedt and his fellow researchers exposed minuscule clusters of xenon atoms to two consecutive X-ray pulses. The clusters, which were merely three millionths of an inch across, were heated by the first pulse for 10 quadrillionths of a second, or 10 femtoseconds. The second pulse then probed the clusters’ atomic structures over the next 80 femtoseconds.

    “The unique nature of the LCLS X-ray pulse allowed us to create a freeze-frame movie of the response, with a resolution of about a tenth of the width of a single xenon atom,” says LCLS and Stanford University graduate student Ken Ferguson, who led the data analysis. The researchers believe that the effect is a result of how electrons, which were initially localized around individual xenon atoms, redistribute over the entire cluster after the first X-ray pulse.

    “This phenomenon had never been observed before, nor had it been predicted by any of the existing theories,” he says. “We expect it to have implications for many ultrafast X-ray laser experiments, especially those geared toward single-particle imaging with very intense X-ray pulses.”

    The research could benefit studies in other areas as well, such as investigations of warm dense matter – a state of matter between a solid and a plasma that exists in the cores of certain planets and is also important in the pursuit of nuclear fusion with high-power lasers.

    Other institutions involved in the study were Technical University of Berlin, Germany; Tohoku University, Japan; National Science Foundation BioXFEL Science and Technology Center, Buffalo; and Kyoto University, Japan.

    Citation: K. R. Ferguson et al., Science Advances, 29 January 2016 (10.1126/sciadv.1500837).

    See the full article here .

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  • richardmitnick 4:56 am on January 22, 2016 Permalink | Reply
    Tags: , SLAC LCLS, SLAC LCLS MFX,   

    From SLAC: “New MFX Experimental Station at LCLS Sees First X-ray Light” 


    SLAC Lab

    1.15.16
    No writer credit found

    Instrument Expands X-ray Laser’s Capability and Flexibility for Biological Experiments

    For the first time in three years, LCLS has added a new instrument to its set of experimental stations. Staff from Stanford and SLAC gathered on Jan. 12 in the X-ray laser’s Far Experimental Hall to celebrate the arrival of the first X-rays in the brand new MFX hutch. LCLS’s seventh instrument, MFX will expand the facility’s capability and capacity by generating more opportunities for all kinds of groundbreaking user experiments.

    Although MFX can support a variety of experimental settings, it was specifically designed for macromolecular femtosecond crystallography. This technique provides atomic-resolution X-ray images and ultrafast movies of biomolecules in action. It will aid researchers in unravelling crucial biological processes, from finding new ways of fighting disease to developing methods to harness solar energy similar to photosynthesis.

    “MFX is going to make a big difference for the biosciences community, which has a growing demand for X-ray laser studies,” said SLAC and Stanford researcher Soichi Wakatsuki, the principal investigator for the MFX grants that initiated the project. “The instrument will increase the number of biological experiments at LCLS and will allow us to do them more efficiently.”

    SLAC LCLS Far Experimental Hall
    LCLS’s new instrument for macromolecular femtosecond crystallography, MFX, is located in the X-ray laser’s Far Experimental Hall. (SLAC National Accelerator Laboratory)

    So far, studies of biological samples have taken place at several other LCLS instruments, including AMO and SXR, but primarily at XPP and CXI. Their versatile, multi-purpose research programs require frequent, time-consuming changes in the experimental setups and limit the time available for biostudies. MFX will help alleviate both issues.

    But the addition of the new experimental station will benefit more than just bio-interested users. Since the X-ray beam can now be distributed between more instruments than before, there will be more experimental time for non-MFX users as well. The new in-hutch instrumentation, which is the focus of ongoing and future R&D, is rapidly expanding the MFX scientific capabilities in new directions.

    Building the new hutch in the Far Experimental Hall took place over the past six months. Now, more equipment will be brought in to prepare for the first MFX user experiments in July.
    A Collaborative Effort

    “It only took a little more than two-and-a-half years from the initial idea for MFX to today’s first light,” said LCLS scientist and MFX project manager Sébastien Boutet. “None of this would have happened without the collaboration of many great people – technicians, designers, engineers, researchers and construction workers.”

    LCLS ALD Mike Dunne said, “MFX is a great example of the successful collaboration between Stanford, SLAC’s Biosciences Division, SSRL and LCLS, and it may be a model for future projects that bring people together to do something remarkable.”

    Similar statements were also made by others at the first-light event.

    Persis Drell, dean of the Stanford School of Engineering and former SLAC director, emphasized that it was the inspiration of researchers from both SLAC and Stanford that laid the ground for the new instrument, which will make LCLS more accessible to users from around the world.

    SSRL Science Director Britt Hedman pointed out that MFX is also a gateway for scientists who want to do new types of crossover experiments that make use of both X-ray light sources, LCLS and SSRL. On the SSRL side, MFX efforts are led by researcher Aina Cohen, who also oversaw the development of a broadly used experimental setup at XPP that will now be used at MFX.

    SLAC LCLS MFX
    SLAC LCLS MFX

    “Today’s first light is a major milestone, but it’s not the end of MFX construction yet,” Wakatsuki said. “In the near future, we’ll install advanced instrumentation capable of rapid and automated use of LCLS’s X-rays, and turn MFX into a highly optimized system that will further increase the scientific productivity of the facility.”

    The MFX project received financial support from the Department of Energy’s Office of Science, Biological and Environmental Research (BER) and Basic Energy Sciences (BES); the National Institute of General Medical Sciences; Stanford University and the Howard Hughes Medical Institute.

    See the full article here .

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  • richardmitnick 1:37 pm on December 8, 2015 Permalink | Reply
    Tags: , Ribosome research, SLAC LCLS,   

    From SLAC: “Innovation Boosts Study of Fragile Biological Samples at SLAC’s X-ray Laser” 


    SLAC Lab

    December 8, 2015

    1
    Hasan DeMirci, a SLAC scientist with the Stanford PULSE Institute, with equipment used to prepare delicate biological samples for study with the lab’s X-ray laser, the Linac Coherent Light Source. (SLAC National Accelerator Laboratory)

    2
    Hasan DeMirci and Raymond Sierra

    3
    Diagram of the experimental setup at SLAC’s Linac Coherent Light Source. Gently prepared samples of fragile biological complexes are dropped into the path of the X-ray laser pulses, which enter from bottom right (yellow dashed line). At the interaction point where they meet, X-rays bounce off atoms in the sample and scatter into a detector, bottom left, producing patterns that are used to reconstruct the sample’s atom-by-atom structure. (R. Sierra et al., Nature Methods)

    Researchers at the Department of Energy’s SLAC National Accelerator Laboratory have found a simple new way to study very delicate biological samples – like proteins at work in photosynthesis and components of protein-making machines called ribosomes – at the atomic scale using SLAC’s X-ray laser.

    Hasan DeMirci, a SLAC scientist with the Stanford PULSE Institute who teamed up with graduate student Raymond Sierra on the new system, has been using the Linac Coherent Light Source (LCLS) X-ray laser – a DOE Office of Science User Facility – to zero in on the details of ribosomes at work.

    SLAC LCLS Inside
    LCLS

    In addition to their universal role in deciphering the genetic code to build proteins, ribosomes are also important targets for antibiotic treatments.

    It is difficult to form ribosomes into crystals so they can be studied with X-rays because they are very fragile. The new system sprang from a desire to better preserve the ribosome crystals.

    The research team did this by keeping the tiny crystals in the same solution they were grown in at temperatures approaching those in their natural environment, and by finding a more gentle way to deliver or “inject” them into a vacuum chamber, where they are struck by LCLS X-ray pulses.

    One Stream Protects Another

    The new system, dubbed coMESH, uses low-cost, off-the-shelf components to shape and protect a stream of crystallized proteins with a surrounding stream of electrically charged fluid. It was successfully tested in a 2014 experiment and featured in the Nov. 30 online edition of Nature Methods.

    “Our strategy was to come up with an injector that can handle anything, not just ribosomes,” DeMirci said. “We are addressing a definite need in the scientific community for a more universal way to deliver samples to LCLS.”

    In addition to demonstrating that the new system worked, the experiments also gave the scientists a more detailed, 3-D look at how one component of the ribosome binds to an antibiotic called paromomycin that is used to treat parasitic infections. “Now we have a more realistic picture of how this antibiotic interacts with ribosomes at temperatures close to those in their natural environment,” DeMirci said.

    The new system consists of a thin tube, about one-tenth of a millimeter in diameter, inside a slightly larger tube; the sizes can vary based on the dimensions of the crystal samples.

    A charging electrode applies low electrical current to the fluid in the larger tube, which focuses the flow to a thin filament. Both tubes end at the same point and the electrical current in the outer fluid greatly narrows both streams of fluid as they emerge from the tubes.

    Less Damage and Waste

    The system is also designed to waste fewer crystals in experiments than some other sample delivery methods. The thickness and flow rate of the inner stream can be fine-tuned by changing the applied voltage and the width of the tubing to maximize the rate at which X-ray pulses strike the crystals flowing into their path.

    DeMirci and Sierra said that based on the 3-D atomic-scale details they were able to see in the ribosome-drug complex and in samples of a photosynthetic protein complex known as photosystem-II, it doesn’t appear the voltage damaged the protein structures.

    “It’s like birds sitting on an electrical wire,” DeMirci said.

    DeMirci and Sierra said they expect the coMESH system will find wider use by other scientists conducting experiments at LCLS. “We want this to be ‘plug-and-play,'” Sierra said, “so all they have to think about during their experiment is collecting data and not troubleshooting sample delivery.”

    Citation: R.G. Sierra et al. Nature Methods, 30 November 2015 (10.1038/nmeth.3667)

    See the full article here .

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  • richardmitnick 3:23 pm on October 5, 2015 Permalink | Reply
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    From SLAC: “200-terawatt Laser Brings New Extremes in Heat, Pressure to X-ray Experiments” 


    SLAC Lab

    October 5, 2015

    1
    An upgraded high-power laser is designed to synchronize with X-rays for high-temperature, high-pressure experiments in this large chamber, at left. The chamber is in the Matter in Extreme Conditions experimental station at SLAC’s Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    2
    A view of the large crystal that is integral to a high-power laser system at SLAC’s Matter in Extreme Conditions experimental station at the Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    3
    Eduardo Granados, a laser scientist at SLAC, inspects a large titanium-sapphire crystal, a key component in a newly upgraded high-power laser system. The laser system is designed to work in conjunction with pulses from SLAC’s Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    A newly upgraded high-power laser at the Department of Energy’s SLAC National Accelerator Laboratory will blaze new trails across many fields of science by recreating the universe’s most extreme conditions, such as those at the heart of stars and planets, in a lab.

    It is the first high-power laser system to be paired with SLAC’s X-ray laser, the Linac Coherent Light Source (LCLS).

    SLAC LCLS
    LCLS
    SLAC LCLS Inside
    Inside the LCLS

    LCLS can precisely measure extreme forms of matter created by the high-power pulses – with temperatures reaching millions of degrees and pressures approaching 2 billion tons per square inch, about 300 billion times the pressure at sea level – as it rapidly transforms at the atomic scale. The upgraded laser will be useful for studying how materials transform under stress and for understanding the physics of nuclear fusion, which could one day serve as a revolutionary source of energy.

    Scientists can also use its pulses to drive a variety of particle beams that explore forms of matter, such as star-like dense plasmas, in new ways. Plasmas, which are considered a fourth state of matter because they are not like solids, liquids or gases, consist of a gassy soup of charged particles that includes free-floating electrons and the atoms the electrons were stripped away from.

    “This will give us more insight into the processes at work, from the atomic to electronic states,” said Eduardo Granados, a laser scientist at SLAC who oversaw the upgrade.

    The upgraded laser system is designed to reach a peak of 200 terawatts of power, seven times higher than its previous peak and equivalent to about 100 times the world’s total power consumption compressed into tens of femtoseconds, or quadrillionths of a second. Its peak power before the upgrade was 30 terawatts. The laser’s pulses are now far more powerful than the total combined pulse power of the more than 150 other laser systems in operation at SLAC.

    New Ways to Probe Materials

    Even though SLAC’s upgraded laser is not the most powerful in the world – a laser completed in Japan this year now holds the record, with roughly 10 times higher power, and many other laser systems around the globe are several times more powerful – what makes it unique is its ability to synchronize with the intense, ultrafast X-ray pulses produced at LCLS, a DOE Office of Science User Facility.

    The growth in these high-power laser systems around the globe opens new avenues for discovery and has excited interest among researchers working in astrophysics, materials research, planetary sciences, geology, and nuclear and energy sciences, among other fields. On Sept. 30, an international symposium organized by the Science Council of Japan met at SLAC to discuss the latest developments in using high-power lasers and X-ray lasers to study matter at extreme conditions, and similar discussions are planned during a two-day High-Power Laser Workshop this week at SLAC and during an upcoming lab-based astrophysics conference at SLAC.

    SLAC’s high-power laser emits light pulses at invisible, near-infrared frequencies that push samples to extreme conditions; the X-ray laser then probes their properties with incredible precision. Both laser systems can produce pulses measured in femtoseconds, and the timing delay between the high-power and X-ray pulses can be adjusted to study how materials rapidly transform after they are hit by the high-power laser pulse.

    The high-power laser can also be used to simultaneously generate beams of particles such as gamma rays, protons and a specialized form of X-rays called betatron radiation all of which can be used in concert with LCLS pulses to explore exotic states of matter in new ways.

    “We will now have a much more accurate picture of what’s happening in high-energy X-ray laser experiments,” Granados said.

    Opportunity for Future Upgrades

    At the core of SLAC’s upgraded laser system, which is housed at the Matter in Extreme Conditions experimental station at LCLS, is a large, high-quality titanium-sapphire crystal, measuring more than 3 inches in diameter. The crystal stimulates and amplifies light from another laser. That amplified light is focused down to a spot just millionths of an inch across, and timing systems help to synch the arrival of each laser pulse with an LCLS X-ray laser pulse with a precision measured in femtoseconds.

    The upgraded high-power laser at LCLS will be available to scientists during the next round of experiments at LCLS, which begins in October, at half of its designed peak power, 100 terawatts. The plan is to gradually ramp up its intensity over time toward regular operation at 200 terawatts, Granados said. The laser will initially be able to fire one pulse every 3.5 minutes at 100 terawatts, with a pulse length of about 40 femtoseconds. At its peak power of 200 terawatts, it will fire one shot every seven minutes.

    Granados said the laser system can eventually be upgraded further, up to 300 terawatts and perhaps as high as 400 terawatts, with additional equipment.

    Even before the upgrade the laser system was used for a first-of-a-kind LCLS experiment that used its pulse to produce a secondary surge of X-rays in the form of betatron X-rays. Those betatron X-rays, which cover a broader energy range than the LCLS pulses and were produced by accelerating high-energy electrons with laser light, were used to reveal more details about the samples.

    “These betatron X-rays are a promising source for future experiments that we now want to test at higher energies,” Granados said.

    See the full article here .

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  • richardmitnick 3:55 pm on July 27, 2015 Permalink | Reply
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    From SLAC: “New ‘Molecular Movie’ Reveals Ultrafast Chemistry in Motion” 


    SLAC Lab

    June 22, 2015


    This video describes how the Linac Coherent Light Source, an X-ray free-electron laser at SLAC National Accelerator Laboratory, provided the first direct measurements of how a ring-shaped gas molecule unravels in the millionths of a billionth of a second after it is split open by light. The measurements were compiled in sequence to form the basis for computer animations showing molecular motion. (SLAC National Accelerator Laboratory)

    Scientists for the first time tracked ultrafast structural changes, captured in quadrillionths-of-a-second steps, as ring-shaped gas molecules burst open and unraveled. Ring-shaped molecules are abundant in biochemistry and also form the basis for many drug compounds. The study points the way to a wide range of real-time X-ray studies of gas-based chemical reactions that are vital to biological processes.

    1
    This illustration shows shape changes that occur in quadrillionths-of-a-second intervals in a ring-shaped molecule that was broken open by light. The molecular motion was measured using SLAC’s Linac Coherent Light Source X-ray laser. The colored chart shows a theoretical model of molecular changes that syncs well with the actual results. The squares in the background represent panels in an LCLS X-ray detector. (SLAC National Accelerator Laboratory)

    Researchers working at the Department of Energy’s SLAC National Accelerator Laboratory compiled the full sequence of steps in this basic ring-opening reaction into computerized animations that provide a “molecular movie” of the structural changes.

    Conducted at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the pioneering study marks an important milestone in precisely tracking how gas-phase molecules transform during chemical reactions on the scale of femtoseconds. A femtosecond is a millionth of a billionth of a second.

    “This fulfills a promise of LCLS: Before your eyes, a chemical reaction is occurring that has never been seen before in this way,” said Mike Minitti, a SLAC scientist who led the experiment in collaboration with Peter Weber at Brown University. The results are featured in the June 22 edition of Physical Review Letters.

    “LCLS is a game-changer in giving us the ability to probe this and other reactions in record-fast timescales,” Minitti said, “down to the motion of individual atoms.” The same method can be used to study more complex molecules and chemistry.

    The free-floating molecules in a gas, when studied with the uniquely bright X-rays at LCLS, can provide a very clear view of structural changes because gas molecules are less likely to be tangled up with one another or otherwise obstructed, he added. “Until now, learning anything meaningful about such rapid molecular changes in a gas using other X-ray sources was very limited, at best.”

    New Views of Chemistry in Action

    The study focused on the gas form of 1,3-cyclohexadiene (CHD), a small, ring-shaped organic molecule derived from pine oil. Ring-shaped molecules play key roles in many biological and chemical processes that are driven by the formation and breaking of chemical bonds. The experiment tracked how the ringed molecule unfurls after a bond between two of its atoms is broken, transforming into a nearly linear molecule called hexatriene.

    “There had been a long-standing question of how this molecule actually opens up,” Minitti said. “The atoms can take different paths and directions. Tracking this ultimately shows how chemical reactions are truly progressing, and will likely lead to improvements in theories and models.”

    The Making of a Molecular Movie

    In the experiment, researchers excited CHD vapor with ultrafast ultraviolet laser pulses to begin the ring-opening reaction. Then they fired LCLS X-ray laser pulses at different time intervals to measure how the molecules changed their shape.

    Researchers compiled and sorted over 100,000 strobe-like measurements of scattered X-rays. Then, they matched these measurements to computer simulations that show the most likely ways the molecule unravels in the first 200 quadrillionths of a second after it opens. The simulations, performed by team member Adam Kirrander at the University of Edinburgh, show the changing motion and position of its atoms.

    Each interval in the animations represents 25 quadrillionths of a second ­– about 1.3 trillion times faster than the typical 30-frames-per-second rate used to display TV shows.

    “It is a remarkable achievement to watch molecular motions with such incredible time resolution,” Weber said.

    A gas sample was considered ideal for this study because interference from any neighboring CHD molecules would be minimized, making it easier to identify and track the transformation of individual molecules. The LCLS X-ray pulses were like cue balls in a game of billiards, scattering off the electrons of the molecules and onto a position-sensitive detector that projected the locations of the atoms within the molecules.

    A Successful Test Case for More Complex Studies

    “This study can serve as a benchmark and springboard for larger molecules that can help us explore and understand even more complex and important chemistry,” Minitti said.

    Additional contributors included scientists at Brown and Stanford universities in the U.S. and the University of Edinburgh in the U.K. The work was supported by the DOE Office of Basic Energy Sciences.

    See the full article here.

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  • richardmitnick 1:26 pm on July 7, 2015 Permalink | Reply
    Tags: , SLAC LCLS,   

    From SLAC: “Scientists Drive Tiny Shock Waves Through Diamond” 


    SLAC Lab

    July 6, 2015

    X-ray Laser Brings the Physics of Exploding Stars into the Lab

    1
    Researchers prepare for an experiment in the Matter in Extreme Conditions station’s chamber at SLAC’s Linac Coherent Light Source X-ray laser. (SLAC National Accelerator Laboratory)

    Researchers have used an X-ray laser to record, in detail never possible before, the microscopic motion and effects of shock waves rippling across diamond.

    The technique, developed at the Department of Energy’s SLAC National Accelerator Laboratory, allows scientists to precisely explore the complex physics driving massive star explosions, which are critical for understanding fusion energy, and to improve scientific models used to study these phenomena.

    “What is really exciting is that we can capture images of what happens on microscopic scales,” said Bob Nagler, a staff scientist at the Linac Coherent Light Source (LCLS) X-ray laser, a DOE Office of Science User Facility. “People have used X-rays to produce images of shock waves, but never on the tiny scale that LCLS makes possible.” The results were published June 18 in Scientific Reports.

    The ability to measure shock wave properties so clearly at this scale, down to one-thousandth of a meter, can be useful to understanding the fundamental physics at work on far larger scales, too, he said.

    Using X-rays to ‘Freeze’ Shock Waves

    In the experiment, researchers used a powerful optical laser pulse to trigger shock waves in thin, inch-long slivers of diamond. Then they hit the diamond samples with LCLS X-ray pulses at time intervals of hundreds of trillionths of a second, or hundreds of picoseconds. The optical laser destroyed the diamond samples, so new samples were required for each image.

    2
    This sequence of phase-contrast images (a-d) shows a shock wave passing through diamond. The time delay after the start of the shock wave is displayed in nanoseconds (“ns”) for each image. Images e-h are enhanced to more clearly reveal the shock wave features. The dotted box in Figure f shows the area used to measure the compression of the diamond sample caused by the light-triggered shock wave. (DESY)


    This movie shows a shock wave passing through thin diamond. The movie uses a sequence of images that were collected at different time points using SLAC’s Linac Coherent Light source X-ray laser. The movie slows down a process that spanned just 3 nanoseconds, or billionths of a second, and is measured in tens of microns, or hundredths of millimeters. (DESY)

    Researchers compiled the resulting X-ray images into an ultra-slow-motion “movie” about 3 billionths of a second long that shows how a shock wave whips through the diamond faster than the speed of sound.

    “LCLS’ pulses, just 50 quadrillionths of a second long, ‘freeze’ the motion of this elastic wave as it’s propagating through the material,” said Andreas Schropp, the lead author of the study, who is a staff scientist at Germany’s DESY lab.

    The researchers used an X-ray technique called magnified phase-contrast imaging to translate density changes in diamond into vivid, high-resolution shock wave images.

    The experiment yielded information about the compression of the diamond’s structure and the pressure changes caused by the shock wave.

    Upgrades Provide a View Inside Shocked Materials

    The experiment was one of the first using a specialized Matter in Extreme Conditions experimental station at LCLS that is designed to explore extreme states, including those never before directly measured and observed, using powerful X-rays.

    The optical lasers have since been upgraded to reach higher powers, and scientists now have the ability to couple shock wave imaging with another X-ray technique, called wide-angle X-ray scattering, that allows them to explore changes to the atomic structure of the material during a shock wave.

    “This allows us to see how materials behave when they melt, to see the dynamics of materials as they change from one structure to the next,” Nagler said. “This has implications for geoscience, such as understanding the physics of matter deep inside the interior of large planets.”

    Nagler said SLAC scientists have also just completed a new standardized platform that will make it far easier to set up and conduct a wide range of shock wave experiments using different materials and laser configurations.

    Researchers participating in the study were from SLAC’s LCLS; Lawrence Livermore National Laboratory; DESY lab and Dresden University of Technology in Germany; Swinburne University of Technology in Australia; and University of Oxford in the U.K. This work was supported by the DOE Office of Science, Fusion Energy Science; DOE Office of Basic Energy Sciences; Volkswagen Foundation; and the German Ministry of Education and Research.

    See the full article here.

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 8:49 am on April 2, 2015 Permalink | Reply
    Tags: , , SLAC LCLS,   

    From SLAC: “Scientists Track Ultrafast Creation of a Catalyst with X-ray Laser” 


    SLAC Lab

    April 1, 2015

    Chemical Transformations Driven by Light Provide Key Insight to Steps in Solar-energy Conversion

    1
    This artistic rendering shows an iron-centered molecule that is severed by laser light (upper left). Within hundreds of femtoseconds, or quadrillionths of a second, a molecule of ethanol from a solvent rushes in (bottom right) to bond with the iron-centered molecule. (SLAC National Accelerator Laboratory)

    An international team has for the first time precisely tracked the surprisingly rapid process by which light rearranges the outermost electrons of a metal compound and turns it into an active catalyst – a substance that promotes chemical reactions.

    The results, published April 1 in Nature, could help in the effort to develop novel catalysts to efficiently produce fuel using sunlight. The research was performed with an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory.

    “We were able to determine how light rearranges the outermost electrons of the compound on timescales down to a few hundred femtoseconds, or quadrillionths of a second,” said Philippe Wernet, a scientist at Helmholtz-Zentrum Berlin for Materials and Energy who led the experiment.

    Researchers hope that learning these details will allow them to develop rules for predicting and controlling the short-lived early steps in important reactions, including the ones plants use to turn sunlight and water into fuel during photosynthesis. Scientists are seeking to replicate these natural processes to produce hydrogen fuel from sunlight and water, for example, and to master the chemistry required to produce other renewable fuels.

    “The eventual goal is to design chemical reactions that behave exactly the way you want them to,” Wernet said.

    In the experiment at SLAC’s Linac Coherent Light Source, a DOE Office of Science User Facility, the scientists studied a yellowish fluid called iron pentacarbonyl, which consists of carbon monoxide “spurs” surrounding a central iron atom. It is a basic building block for more complex compounds and also provides a simple model for studying light-induced chemical reactions.

    SLAC LCLS Inside
    LCLS

    Researchers had known that exposing this iron compound to light can cleave off one of the five carbon monoxide spurs, causing the molecule’s remaining electrons to rearrange. The arrangement of the outermost electrons determines the molecule’s reactivity – including whether it might make a good catalyst – and also informs how reactions unfold.

    What wasn’t well understood was just how quickly this light-triggered transformation occurs and which short-lived intermediate states the molecule goes through on its way to becoming a stable product.

    At LCLS, the scientists struck a thin stream of the iron compound, which was mixed into an ethanol solvent, with pulses of optical laser light to break up the iron-centered molecules. Just hundreds of femtoseconds later, an ultrabright X-ray pulse probed the molecules’ transformation, which was recorded with sensitive detectors.

    By varying the arrival time of the X-ray pulses, they tracked the rearrangements of the outermost electrons during the molecular transformations.

    Roughly half of the severed molecules enter a chemically reactive state in which their outermost electrons are prone to binding other molecules. As a consequence, they either reconnect with the severed part or bond with an ethanol molecule to form a new compound. In other cases the outermost electrons in the molecule stabilize themselves in a configuration that makes the molecule non-reactive. All of these changes were observed within the time it takes light to travel a few thousandths of an inch.

    “To see this happen so quickly was extremely surprising,” Wernet said.

    Several years’ worth of data analysis and theoretical work were integral to the study, he said. The next step is to move on from model compounds to LCLS studies of the actual molecules used to make solar fuels.

    “This was a really exciting experiment, as it was the first time we used the LCLS to study chemistry in a liquid compound,” said Josh Turner, a SLAC staff scientist who participated in the experiment. “The LCLS is unique in the world in its ability to resolve these types of ultrafast processes in the right energy range for this compound.”

    SLAC’s Kelly Gaffney, a chemist who contributed expertise in how the changing arrangement of electrons steered the chemical reactions, said, “This work helps set the stage for future studies at LCLS and shows how cooperation across different research areas at SLAC enables broader and better science.”

    In addition to researchers from Helmholtz-Zentrum Berlin for Materials and Energy and LCLS, other scientists who assisted in the study were from: SLAC’s Stanford Synchrotron Radiation Lightsource; the SLAC and Stanford PULSE Institute; University of Potsdam, Max Planck Institute for Biophysical Chemistry, Goettingen University and DESY lab in Germany; Stockholm University and MAX-lab in in Sweden; Utrecht University in the Netherlands; Paul Scherrer Institute in Switzerland; and the University of Pennsylvania.

    This work was supported by the Volkswagen Foundation, the Swedish Research Council, the Carl Tryggers Foundation, the Magnus Bergvall Foundation, Collaborative Research Centers of the German Science Foundation and the Helmholtz Virtual Institute “Dynamic Pathways in Multidimensional Landscapes,” and the U.S. Department of Energy Office of Science.

    See the full article here.

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 12:03 pm on March 24, 2015 Permalink | Reply
    Tags: , SLAC LCLS, Warm Dense Matter,   

    From SLAC: “Experiment Provides the Best Look Yet at ‘Warm Dense Matter’ at Cores of Giant Planets” 


    SLAC Lab

    March 23, 2015

    Shock Wave Experiment at SLAC’s X-ray Laser Tracks Formation of a Mysterious Type of Matter

    In an experiment at the Department of Energy’s SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as it transitions into a superhot, highly compressed concoction known as “warm dense matter.”

    1
    This illustration shows a cutaway view of Jupiter, which is believed to contain “warm dense matter” at its core. A study at SLAC’s Linac Coherent Light Source X-ray laser has provided the most detailed measurements yet of a material’s temperature and compression as it transitions into this exotic state of matter. (SLAC National Accelerator Laboratory)

    Warm dense matter is the stuff believed to be at the cores of giant gas planets in our solar system and some of the newly observed “exoplanets” that orbit distant suns, which can be many times more massive than Jupiter. Their otherworldly properties, which stretch our understanding of planetary formation, have excited new interest in studies of this exotic state of matter.

    The results of the SLAC study, published March 23 in Nature Photonics, could also lead to a greater understanding of how to produce and control nuclear fusion, which scientists hope to harness as a new source of energy.

    “The heating and compression of warm dense matter has never been measured before in a laboratory with such precise timing,” says Siegfried Glenzer, a distinguished staff scientist who is part of the Stanford Institute for Materials and Energy Sciences (SIMES) at SLAC. “We have shown the detailed steps of how a solid hit by powerful lasers becomes a compressed solid and a dense plasma at the same time. This is a step on the path toward creating fusion in the lab.”


    This video describes how scientists at SLAC created and precisely measured the temperature and compression in “warm dense matter,” an exotic state that is believed to exist at the core of giant planets like Jupiter. (SLAC National Accelerator Laboratory)

    A team led by Glenzer used laser light to compress ultrathin aluminum foil samples to a pressure more than 4,500 times higher than the deepest ocean depths and superheat it to 20,000 kelvins – about four times hotter than the surface of the sun. SLAC’s Linac Coherent Light Source X-ray laser, a DOE Office of Science User Facility, then precisely measured the foil’s properties as it transformed into warm dense matter and then into a plasma – a very hot gas of electrons and supercharged atoms.

    SLAC LCLSII
    SLAC LCLS Inside
    LCLS

    Warm dense matter remains largely mysterious because it is difficult to create and study in a laboratory, can exhibit properties of several types of matter and occupies a middle ground between solid and plasma. Our own sun is an example of a self-sustaining plasma, and plasmas have also been harnessed in some TV displays.

    While warm dense matter is believed to exist in a stable state at the heart of giant planets, in a laboratory it lasts just billionths of a second. Scientists have relied largely on computer simulations, driven by scientific theories, to help explain how a solid, when shocked with powerful lasers, transforms into a plasma.

    LCLS, with its complement of high-power lasers, is uniquely suited to creating and studying matter at the extremes. Its ultrabright X-ray pulses are measured in femtoseconds, or quadrillionths of a second, so it works like an ultra-high-speed X-ray camera to illuminate and record the properties of the most fleeting phenomena in atomic-scale detail.

    In this experiment, researchers used a high-power optical laser at LCLS’s Matter in Extreme Conditions experimental station to fire separate beams of green laser light simultaneously at both sides of coated, ultrathin aluminum foil samples, each just half the width of an average human hair. The lasers produced shock waves in the material that converged to create extreme temperatures and pressures.

    3
    Scientists prepare for an experiment at SLAC’s Matter in Extreme Conditions (MEC) station, part of the Linac Coherent Light Source X-ray laser. They used this MEC station to create and measure the properties of ultrathin sheets of superheated aluminum as it transitioned into warm dense matter, an exotic state of matter.(SLAC National Accelerator Laboratory)

    Researchers struck the samples with X-rays just nanoseconds later, and varied the arrival time of the X-rays to essentially make a series of snapshots of warm dense matter formation. The team used a technique known as small angle X-ray scattering to measure the internal structure of the material, capturing its brief transition into the warm dense state.

    “This early work with aluminum is a first stepping stone toward other problems we really need to solve,” Glenzer said, such as how hydrogen behaves under similar conditions. Hydrogen, which makes up about 75 percent of the visible mass of the universe, plays a central role in fusion, the process that powers stars. A better understanding of how hydrogen transitions into warm dense matter could help settle debates over conflicting theories on this transition and help unlock the secrets of fusion energy.

    “I think LCLS can help to resolve the hydrogen ‘controversy,’ in upcoming experiments,” Glenzer said.

    Participants in the research included scientists at SLAC, University of California Berkeley, Lawrence Livermore National Laboratory and General Atomics; QuantumWise A/S in Denmark; AWE plc, University of Warwick and University of Oxford in the U.K.; and the Max Planck Institute for the Physics of Complex Systems, Institute for Optics and Quantum Electronics, Friedrich-Schiller-University and GSI Helmholtz Center for Heavy Ion Research in Germany.

    The work was supported by the DOE Office of Science, Fusion Energy Science; the DOE Office of Basic Energy Sciences, Materials Sciences and Engineering Division; Lawrence Livermore National Laboratory; a Laboratory Directed Research and Development grant; and the Peter-Paul-Ewald Fellowship of the VolkswagenStiftung.

    See the full article here.

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 8:41 am on March 19, 2015 Permalink | Reply
    Tags: , , , , SLAC LCLS,   

    From SLAC: “Scientists Watch Quantum Dots ‘Breathe’ in Response to Stress” 


    SLAC Lab

    March 18, 2015

    Nanocrystal Study at SLAC’s X-ray Laser Could Aid in the Design of New Materials

    1
    In this illustration, intense X-rays produced at SLAC’s Linac Coherent Light Source strike nanocrystals of a semiconductor material. Scientists used the X-rays to study an ultrafast “breathing” response in the crystals induced quadrillionths of a second earlier by laser light. (SLAC National Accelerator Laboratory)

    Researchers at the Department of Energy’s SLAC National Accelerator Laboratory watched nanoscale semiconductor crystals expand and shrink in response to powerful pulses of laser light. This ultrafast “breathing” provides new insight about how such tiny structures change shape as they start to melt – information that can help guide researchers in tailoring their use for a range of applications.

    In the experiment using SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, a DOE Office of Science User Facility, researchers first exposed the nanocrystals to a burst of laser light, followed closely by an ultrabright X-ray pulse that recorded the resulting structural changes in atomic-scale detail at the onset of melting.

    SLAC LCLS Inside
    LCLS

    “This is the first time we could measure the details of how these ultrasmall materials react when strained to their limits,” said Aaron Lindenberg, an assistant professor at SLAC and Stanford who led the experiment. The results were published March 12 in Nature Communications.

    Getting to Know Quantum Dots

    The crystals studied at SLAC are known as “quantum dots” because they display unique traits at the nanoscale that defy the classical physics governing their properties at larger scales. The crystals can be tuned by changing their size and shape to emit specific colors of light, for example.

    So scientists have worked to incorporate them in solar panels to make them more efficient and in computer displays to improve resolution while consuming less battery power. These materials have also been studied for potential use in batteries and fuel cells and for targeted drug delivery.

    Scientists have also discovered that these and other nanomaterials, which may contain just tens or hundreds of atoms, can be far more damage-resistant than larger bits of the same materials because they exhibit a more perfect crystal structure at the tiniest scales. This property could prove useful in battery components, for example, as smaller particles may be able to withstand more charging cycles than larger ones before degrading.

    A Surprise in the ‘Breathing’ of Tiny Spheres and Nanowires

    In the LCLS experiment, researchers studied spheres and nanowires made of cadmium sulfide and cadmium selenide that were just 3 to 5 nanometers, or billionths of a meter, across. The nanowires were up to 25 nanometers long. By comparison, amino acids – the building blocks of proteins – are about 1 nanometer in length, and individual atoms are measured in tenths of nanometers.

    By examining the nanocrystals from many different angles with X-ray pulses, researchers reconstructed how they change shape when hit with an optical laser pulse. They were surprised to see the spheres and nanowires expand in width by about 1 percent and then quickly contract within femtoseconds, or quadrillionths of a second. They also found that the nanowires don’t expand in length, and showed that the way the crystals respond to strain was coupled to how their structure melts.

    In an earlier, separate study, another team of researchers had used LCLS to explore the response of larger gold particles on longer timescales.

    “In the future, we want to extend these experiments to more complex and technologically relevant nanostructures, and also to enable X-ray exploration of nanoscale devices while they are operating,” Lindenberg said. “Knowing how materials change under strain can be used together with simulations to design new materials with novel properties.”

    Participating researchers were from SLAC, Stanford and two of their joint institutes, the Stanford Institute for Materials and Energy Sciences (SIMES) and Stanford PULSE Institute; University of California, Berkeley; University of Duisburg-Essen in Germany; and Argonne National Laboratory. The work was supported by the DOE Office of Science and the German Research Council.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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