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  • richardmitnick 1:18 pm on May 10, 2016 Permalink | Reply
    Tags: , Experimental advance offers a first glimpse of the biophysics of vision, SLAC LCLS,   

    From U Chicago: “Experimental advance offers a first glimpse of the biophysics of vision” 

    U Chicago bloc

    University of Chicago

    May 5, 2016
    John Easton

    1
    UChicago researchers participated in an experiment that revealed how a protein from photosynthetic bacteria changes shape in response to light in less than a trillionth of a second.
    Courtesy of SLAC National Accelerator Laboratory

    In a groundbreaking experiment using the world’s fastest camera, a team of scientists led by the University of Wisconsin-Milwaukee documented the fundamental processes of a chemical reaction as they occurred in real time. This means seeing how proteins, the building blocks of life, work in a few quadrillionths of a second.

    In a paper published* May 5 in the journal Science, the researchers describe how they acquired images of the effect of light on a tiny crystallized protein.

    Light absorption by proteins is the primary event of processes such as vision and photosynthesis that are fundamental to many life forms. The researchers focused on photoactive yellow protein, a light-absorbing component found in certain bacteria. The basic chemical process they observed, known as isomerization, also occurs when the retina in the human eye responds to light.

    Understanding how these complex molecules do their job depends on knowing the spatial arrangement of atoms and how their structure changes as they interact with light. Until now, no effective method for detailed observation of molecular movement in such detail was available. The Science paper describes an experimental first.

    “This puts us dramatically closer to understanding the chemistry necessary for all life,” said Marius Schmidt, professor of physics at UW-Milwaukee and the leader of the team. “Discovering the step-by-step process of how proteins function is necessary not only to inform treatment of disease, but also to explore the grand questions of biology.”

    “Light drives much of biology and this novel experiment is a pinnacle in understanding how living systems respond to light,” said Keith Moffat, the Louis Block Professor of Biochemistry & Molecular Biology, who pioneered this experimental approach and developed it over 25 years with his Chicago colleagues.

    The data were collected using the Linac Coherent Light [LCLS] Source X-ray free electron laser, or XFEL, at the SLAC National Accelerator Laboratory—operated by Stanford University for the U.S. Department of Energy Office of Science.

    SLAC/LCLS
    SLAC/LCLS

    At the speed of life

    “Biology happens at short time spans,” explained co-author Jason Tenboer, postdoctoral researcher in Schmidt’s lab. The Linac Coherent Light Source supplied the team with camera frames each lasting about 150 femtoseconds, about 1,000 times faster than any seen in an X-ray experiment before and rapid enough to allow the imaging of the fastest reactions.

    Unveiling the atomic-scale changes in protein molecules as they go about their tasks is important because these changes in structure determine their function. In 2014, Schmidt and colleagues were the first to document changes in a protein molecule over a larger increment of time.

    The scientists mapped the atoms in motion in the photoactive yellow protein as the chemical bonds of a central dye molecule—which is buried within the protein and makes it yellow—rearranged. They documented, for the first time, the structure of the yellow dye within the protein in an electronically excited state.

    For the past 60 years, the only way to examine proteins in three dimensions was with X-ray crystallography. This process shoots X-rays at crystallized proteins. These proteins diffract light and create patterns of dots the way shaking a paintbrush sprays drops on a wall. The pattern provides a fingerprint for that protein. But it is a still snapshot, a single point in time when nothing is moving.

    To capture protein molecules in action, scientists need both an optical laser and an X-ray laser with split-second pulses, which is what the XFEL provides.

    Next, the researchers hope to collect femtosecond details over a bigger range of time to create a slow-motion “movie.” This could ultimately allow scientists to intervene in the process of protein functions by using light.

    “We’re interested in the mechanism of the chemical reaction, with the goal of controlling and steering it in a certain direction with light,” Schmidt said. “We can shape laser pulses for that purpose. We will discover how the molecules march in synchronicity during such processes.”

    Forty-four researchers were involved in this study. In addition to those from UW-Milwaukee, Chicago and Stanford, members of the scientific team came from Arizona State University, Lawrence Livermore National Laboratory, University of Hamburg, State University of New York, Buffalo, University of Jyvaskyla, Max Planck Institute for Structure and Dynamics of Matter, and Imperial College, London.

    *Science paper
    Femtosecond structural dynamics drives the trans/cis isomerization in photoactive yellow protein

    See the full article here .

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    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 7:27 am on May 10, 2016 Permalink | Reply
    Tags: , , RIKEN SACLA, SLAC LCLS,   

    From BNL: “Ultra-fast X-ray Lasers Illuminate Elusive Atomic Spins” 

    Brookhaven Lab

    May 9, 2016
    Justin Eure
    (631) 344-2347
    jeure@bnl.gov

    Peter Genzer
    (631) 344-3174
    genzer@bnl.gov

    New x-ray technique reveals never-before-seen, trillionth-of-a-second magnetic fluctuations that transform the electronic and magnetic properties of materials.

    1
    Brookhaven Lab physicists Pavol Juhas, John Hill, Mark Dean, Yue Cao, and Vivek Thampy, all of the Condensed Matter Physics and Materials Science Department, except Hill, who is director of NSLS-II.

    A quick flash of light can make ordinary materials extraordinary, potentially inducing qualities such as the perfect efficiency of superconductivity even at room temperature. But these subatomic transformations are infamously fleeting—they vanish in just trillionths of a second.

    Now, an international team of scientists has used synchronized infrared and x-ray laser pulses to simultaneously manipulate and reveal the ultra-fast magnetic properties of this promising quantum landscape. The rapid, light-driven switching between magnetic states, explored here with unprecedented precision, could one day revolutionize the reading and writing of data in computers and other digital devices.

    The study, published* May 9, 2016, in the journal Nature Materials, was led by scientists at the U.S. Department of Energy’s Brookhaven National Laboratory and included researchers from the U.S., China, Germany, Japan, Spain, and the UK.

    “We developed a way to reveal light-induced femtosecond magnetic dynamics in as yet unseen detail,” said Mark Dean, a physicist at Brookhaven Lab and lead author on the study. “This brings us closer to perfecting a recipe for manipulating these materials on ultra-fast time scales.”

    This novel x-ray technique, called time-resolved resonant inelastic scattering, revealed the subtle spin correlations, which travel as waves through the material and define its magnetic properties. Crucially, they behaved differently between two- and three-dimensional spaces when sparked by an infrared laser pulse.

    “Within a two-dimensional atomic plane, the novel state lasted just a few picoseconds,” said Brookhaven physicist and study coauthor Yue Cao. “But three-dimensional correlations also cross between planes, and these took hundreds of picoseconds to vanish—on this scale, that difference is tremendous. It is enormously exciting to help pioneer a new technique and see it succeed.”

    The bulk of the experimental work relied on the powerful and precise x-ray lasers available at SLAC National Accelerator Laboratory’s Linac Coherent Light Source, a DOE Office of Science User Facility, and the SACLA facility in Japan.

    SLAC/LCLS
    SLAC/LCLS

    SACLA Free-Electron Laser Riken Japan
    SACLA Free-Electron Laser Riken Japan

    Doping with light

    To introduce novel magnetic and electronic qualities, scientists often use a technique called chemical doping to augment the atomic configuration of a material. Electrons can be meticulously added or removed, but the process is permanent.

    “We wanted to access similar states transiently, so we used photo-doping,” Dean said. “A laser pulse supplies the needed photons, which changes the electron and spin configuration in the sample—the same spins thought to be responsible for phenomena like superconductivity. Moments later, the material returns to its native state.”

    In this work, the scientists used a strontium-iridium-oxygen compound (Sr2IrO4), selected for its strong magnetic interactions. Manipulating spin in the material was relatively easy—the real challenge was catching it in motion.

    Bright, fast flashes

    The collaboration turned to two powerful photon sources: the LCLS and SACLA, both uniquely capable of illuminating a quantum spin wave mid-stride. Both facilities can produce x-ray pulses with extremely short duration and high brightness.

    “Knowing that these facilities could produce fast and accurate enough laser pulses inspired this entire collaboration,” said study coauthor John Hill, the director of Brookhaven Lab’s National Synchrotron Light Source II, another DOE Office of Science User Facility.

    BNL NSLS-II Interior
    BNL NSLS-II

    For the experiment, an initial infrared laser pulse struck the layered Sr2IrO4 compound, destroying the native magnetic state. For a brief moment, the electrons inside the material formed spin waves that rippled through the material and radically changed its electronic and magnetic properties. Trillionths of a second later, an x-ray pulse followed and bounced off those emergent waves. By measuring the change in both momentum and the angles of diffraction, the scientists could deduce the transient electronic and magnetic qualities.

    This specific process of bouncing and tracking x-rays, called resonant inelastic x-ray scattering (RIXS), was also pioneered by members of this collaboration to explore similar phenomena in condensed matter systems. The new research builds on that to include time-resolved data points.

    “Beyond the remarkable capabilities of LCLS and SACLA to supply ultra-short femtosecond x-ray pulses, the challenge we were facing was how to detect the response of the spins,” said study coauthor Xuerong Liu from the Institute of Physics in Beijing. “That is, we needed a specialized x-ray detection system or ‘camera.'”

    The scientists developed a highly specialized RIXS spectrometer, which used millimeter-sized silicon crystals to measure the exact energy of the rebounding x-rays.

    The data revealed a clear difference in the propagation and timescale of the magnetic phenomena, with the inter-layer correlations taking hundreds of times longer to recover than those within each layer.

    “The findings match theoretical expectations, which is encouraging, but more importantly they demonstrate the strength and precision of this technique,” said collaborator Michael Först of the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany. “We can now dive deeper into the mechanism and think of strategies to fine-tune the control of magnetic properties with light.”

    Next, the scientists plan to explore optical pulses at even longer wavelengths, which will shift atoms within the material without directly exciting the electrons and spins. That work may help reveal the native magnetic coupling within the material, which in turn will clarify how to best break that coupling and toggle between different electronic and magnetic states.

    The research was funded in part by the DOE’s Office Science (BES), which supported experimentation at LCLS.

    *Science paper:
    Ultrafast energy- and momentum-resolved dynamics of magnetic correlations in the photo-doped Mott insulator Sr2IrO4

    See the full article here .

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    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 8:38 am on May 6, 2016 Permalink | Reply
    Tags: , , SLAC LCLS,   

    From DESY: “High-speed camera snaps biosensor’s rapid reaction to light” 

    DESY
    DESY

    X-ray study reveals ultrafast dynamics of photoactive yellow protein

    1
    Inner structure of the photactive yellow protein 800 femtoseconds after the trans-to-cis isomerisation has been initiated by an ultrafast blue laser. The chromophore binding pocket is cut open and the chromophore itself is highlighted by the bulls eye. Credit: Marius Schmidt/University of Wisconsin-Milwaukee

    Using a high-speed X-ray camera, an international team of scientist including researchers from DESY has revealed the ultrafast response of a biosensor to light. The study, published* in the US journal Science, shows light-driven atomic motions lasting just 100 quadrillionths of a second (100 femtoseconds). The technique promises insights into the ultrafast dynamics of various light sensitive biomolecules responsible for important biological processes like photosynthesis or vision.

    The team lead by Marius Schmidt from the University of Wisconsin, Milwaukee used the LCLS X-ray laser at SLAC National Accelerator Laboratory in the U.S. to look at the light-sensitive part of a protein called photoactive yellow protein, or PYP.

    SLAC/LCLS
    SLAC/LCLS

    It functions as an “eye” in purple bacteria, helping them sense blue light and stay away from light that is too energetic and potentially harmful.

    For their investigation, the scientists sent a stream of tiny PYP crystals into a sample chamber. There, each crystal was struck by a flash of optical laser light and then, almost immediately after, an X-ray pulse was used to interrogate the protein’s structural response to the light at the atomic level. The structure is determined indirectly from the intricate pattern of X-ray light scattered from the crystal. By varying the time between the two pulses, scientists were able to see how the protein morphed over time. “By placing the various obtained molecular structures in order of the time delay between the optical and X-ray flashes we obtain a molecular movie of the reaction as it evolves from the first step at 100 femtoseconds to several thousand femtoseconds,” explained the first author of the paper, Kanupriya Pande, also from the University of Wisconsin and now at the Center for Free-Electron Laser Science CFEL at DESY.

    “The absorption of light leaves PYP in an excited state from which it relaxes very quickly,” explained Schmidt, the study’s principal investigator. “It does so by rearranging its atomic structure in what is known as trans-to-cis isomerisation. We’re the first to succeed in taking real-time snapshots of this type of reaction.” This type of isomerisation is also what gives vision – in that case the retinal chromophore undergoes a cis-to-trans isomerisation that ultimately leads to neuronal excitation in the eye.

    “We were able to obtain detailed structures at incredibly short time points after the initial absorption event by taking flash X-ray snapshots with the world’s brightest X-ray source,” said co-author Henry Chapman from CFEL at DESY. But, as Pande pointed out, “these are very challenging experiments, where we needed considerable innovation to assign the correct time stamps to hundreds of thousands of X-ray patterns.”

    The researchers had already studied light-induced structural changes in PYP at LCLS before, revealing atomic motions as fast as 10 billionths of a second (10 nanoseconds). By tweaking their experiment with a faster optical laser and better timing tools and sorting, they were now able to improve their speed limit 100,000 times and capture reactions in the protein that are 1,000 times faster than any seen in an X-ray experiment before.

    “The new data show for the first time how the bacterial sensor reacts immediately after it absorbs light,” says co-author Andy Aquila from SLAC. “The initial response, which is almost instantaneous, is absolutely crucial because it creates a ripple effect in the protein, setting the stage for its biological function.”

    The technique could prove valuable to unveil a number of other important ultrafast light-driven processes, for instance how visual pigments in the human eye respond to light, and how absorbing too much of it damages them; how photosynthetic organisms turn light into chemical energy, a process that could serve as a model for the development of new energy technologies; or how atomic structures respond to light pulses of different shape and duration, an important first step toward controlling chemical reactions with light.

    Together with the University of Wisconsin, Milwaukee, SLAC and DESY, the following institutions were involved in this study: Imperial College London, the University of Jyväskylä in Finland, Arizona State University, Max Planck Institute for Structure and Dynamics of Matter in Hamburg, State University of New York at Buffalo, University of Chicago, Lawrence Livermore National Laboratory and University of Hamburg.

    *Science paper:
    Femtosecond structural dynamics drives the trans/cis isomerization in photoactive yellow protein

    See the full article here .

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    desi

    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 5:46 am on April 21, 2016 Permalink | Reply
    Tags: , , SLAC LCLS,   

    From Stanford: “Peering deep into materials with ultrafast science” 

    Stanford University Name
    Stanford University

    March 31, 2016 [Just appeared in social media]
    Glenn Roberts Jr.

    1
    New techniques developed at SLAC and Stanford allow scientists to observe changes at the nanoscale that occur in fractions of a second in response to light. This artist’s conception depicts the first step in the photovoltaic response that light produces in lead titanate.

    Laser light exposes the properties of materials used in batteries and electronics

    Creating the batteries or electronics of the future requires understanding materials that are just a few atoms thick and that change their fundamental physical properties in fractions of a second. Cutting-edge facilities at SLAC National Accelerator Laboratory and Stanford University have allowed researchers like Aaron Lindenberg to visualize properties of these nanoscale materials at ultrafast time scales.

    In one experiment, a team led by Lindenberg showed atoms shifting in trillionths of a second to produce a wrinkle in a 3-atom-thick sample of a material that might someday be used in flexible electronics. Another study observed semiconductor crystals — called “quantum dots” because they defy classical physics at the nanoscale — expand and shrink in response to ultrafast pulses of laser light.

    2
    A three-atom-thick material wrinkles in response to a laser pulse. Understanding these dynamic ripples could provide crucial clues for the development of next-generation solar cells, electronics and catalysts.

    Revealing such intriguing properties at the nanoscale gives clues about the fundamental nature of materials and how they perform in applications we rely on for energy or information.

    “Even though some of these materials are completely embedded in everyday technologies, not a lot is understood about how they work,” says Lindenberg, who is an associate professor of materials science and engineering and of photon science. He is also a principal investigator for two SLAC/Stanford joint institutes — Stanford Institute for Materials and Energy Sciences and Stanford PULSE Institute.

    “Part of the reason some phenomena are not well understood is because they happen so fast – in billionths, trillionths or even quadrillionths of a second. For the first time, we have tools that allow us to see these things,” he says.

    Working at the intersection of materials science and engineering, Lindenberg and his team have a particular focus on finding promising materials for next-generation electronics, light-based data storage technologies and energy applications.

    “There are a broad range of new properties that emerge at the nanoscale,” Lindenberg says. “The tiniest samples, with just tens or hundreds of atoms, can have nearly flawless structures that make them ideal test tubes for very fundamental questions about what happens when a material transforms.”

    The team uses different types of laser light at SLAC and Stanford labs to learn how simple tweaks in the size, shape and design of materials can change their basic properties in unexpected ways, which could lead to new applications. Taking advantage of the powerful X-rays at SLAC facilities, including the Linac Coherent Light Source [LCLS] and the Stanford Synchrotron Radiation Lightsource [SSRL] , they explore ultrafast changes in nanoscale samples.

    SLAC/LCLS
    SLAC/LCLS

    SLAC/SSRL
    SLAC/SSRL

    “We are trying to understand how electrons or atoms move in materials, which in turn determines, for example, the efficiency of solar cells and other energy-related materials, and how materials switch between different forms,” he says. “Ultrafast techniques allow you to see these kinds of things in a completely new way.”

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 11:33 am on April 7, 2016 Permalink | Reply
    Tags: , , SLAC LCLS, World’s Fastest Electron Diffraction Snapshots of Atomic Motions in Gases   

    From SLAC: “World’s Fastest Electron Diffraction Snapshots of Atomic Motions in Gases” 


    SLAC Lab

    April 5, 2016

    1
    Researchers have taken the world’s fastest “electron images” of rotating nitrogen molecules with SLAC’s new instrument for ultrafast electron diffraction (UED), demonstrating the technology’s potential for making real-time molecular movies of chemical reactions. (SLAC National Accelerator Laboratory)


    Ultrafast Electron Diffraction. How it works.
    This animation explains how researchers use high-energy electrons at SLAC to study ultrafast motions of atoms and molecules relevant to important material properties and chemical processes. (SLAC National Accelerator Laboratory)
    Access mp4 video here .

    High-Speed ‘Electron Camera’ Complements SLAC’s Toolbox for Studies of Ultrafast Processes in Nature

    Scientists have made a significant advance toward making movies of extremely fast atomic processes with potential applications in energy production, chemistry, medicine, materials science and more. Using a superfast, high-resolution “electron camera,” a new instrument for ultrafast electron diffraction (UED) at the Department of Energy’s SLAC National Accelerator Laboratory, researchers have captured the world’s fastest UED images of nitrogen molecules rotating in a gas, with a record shutter speed of 100 quadrillionths of a second.

    Scientists have long dreamed of watching nature’s smallest and speediest phenomena in real time. For instance, watching biomolecules facilitate life-sustaining chemical reactions at high speed and in atomic detail could teach scientists new ways of producing efficient chemical catalysts. However, most available techniques excel at speed or detail, not both.

    “Our new UED instrument can do both: It achieves an unprecedented combination of atomic resolution and extraordinary speed,” said researcher Xijie Wang, SLAC’s UED team lead and co-author of a new study published today in Nature Communications. “We’ve taken UED snapshots of atomic motions in gases faster than ever before and demonstrated the technology’s potential for making molecular movies of chemical reactions.”

    SLAC Electron Camera UED
    SLAC Electron Camera UED

    SLAC Director Chi-Chang Kao said, “UED is a major addition to the lab’s outstanding portfolio of ultrafast techniques, complementing our X-ray laser, the Linac Coherent Light Source, and enabling groundbreaking research on complex dynamic systems with wide-ranging implications for chemistry, the biosciences and future materials.” LCLS is a DOE Office of Science User Facility.

    SLAC LCLS Inside
    SLAC/LCLS Inside

    An ‘Electron Camera’ For Ultrasmall, Ultrafast Vision

    UED uses a focused beam of highly energetic electrons to probe samples – in this case, a stream of laser-excited nitrogen gas. Gases are ideal model systems for studying processes in chemistry. Electrons scatter off atoms in the sample and generate a pattern on a detector that researchers use to determine where the sample’s atoms are located. By varying the time between the laser excitation and the electron beam, which comes in very short electron bundles, scientists can track rapid changes in the pattern that correspond to quick motions of the atoms.

    While the technique itself is not new – UED has been under development by several groups throughout the world since the 1980s – it has never been done at this speed for gases.

    “When it comes to studies of gases, SLAC’s instrument is about five times faster than any other UED machine before,” said Jie Yang from the University of Nebraska, Lincoln, who led the study with Markus Guehr, a researcher at SLAC and at Potsdam University in Germany. “This leap in performance is due to the instrument’s superior high-energy electron source, which was originally developed for SLAC’s LCLS. It will help us better understand a whole new range of speedy processes on the atomic level.”

    Taking Snapshots of ‘Molecular Echoes’

    In the new study, the research team demonstrated the instrument’s superb performance by capturing the rapid rotation of nitrogen molecules in a gas.

    Each molecule consists of two nitrogen atoms connected via a strong chemical bond. As the molecules in the gas tumble around, they normally point in random directions. But hitting them with an extremely short laser pulse makes them briefly all point in the same direction. Although they quickly fall out of alignment, they periodically line up again in a sort of “molecular echo.”

    3
    UED study of laser-induced alignment of molecules in nitrogen gas. The red curve shows how the distribution of molecular orientations in the gas changes over time. (1) Nitrogen molecules, which consist of two strongly bound nitrogen atoms, normally point in random directions when they tumble in a gas. (2) With an extremely short laser pulse, scientists orient the molecules so that they all point in the same direction. (3-6) This ordered state only lasts for a very brief moment before it disperses, but the rotating molecules periodically return to it, forming “molecular echoes” during which the nitrogen molecules align again. During the echoes, the molecules also switch rapidly from being aligned in one orientation to being aligned in another one that is perpendicular to the first (3-4 and 5-6). Using SLAC’s new UED instrument, the researchers have for the first time visualized this ultrafast transition (3-4, UED signals shown at the top) in real time and with atomic resolution. (SLAC National Accelerator Laboratory)

    “When the nitrogen molecules do line up again, they also rapidly switch from pointing in one direction to pointing in the perpendicular direction,” Yang said. “This transition takes only 300 quadrillionths of a second.” The team was able to capture this process because the “shutter speed” of the UED instrument was three times faster than the changes in alignment.

    Guehr said, “The entire process had been studied with other methods before, but our research is the first to visualize it both in real time and with a resolution detailed enough to separate the positions of the two nitrogen nuclei in the molecules.”

    Toward Movies of Chemistry in Action

    The researchers hope to use the technology in the near future to film molecules as they vibrate and watch chemical bonds break and form during chemical reactions.

    “We are also looking forward to combining UED with complementary ultrafast studies at LCLS,” Wang said. “Electrons tell us about a material’s structure, whereas X-rays tell us more about its function. Putting both together will give us a more complete picture in groundbreaking studies of all kinds of complex dynamic processes in nature.”

    The research was supported by the DOE Office of Science, the SLAC UED/UEM Initiative Program Development Fund and the National Science Foundation.

    Science Paper:
    Diffractive imaging of a rotational wavepacket in nitrogen molecules with femtosecond megaelectronvolt electron pulses

    Science team:
    Jie Yang, Markus Guehr, Theodore Vecchione, Matthew S. Robinson, Renkai Li, Nick Hartmann, Xiaozhe Shen, Ryan Coffee, Jeff Corbett, Alan Fry, Kelly Gaffney, Tais Gorkhover, Carsten Hast, Keith Jobe, Igor Makasyuk, Alexander Reid, Joseph Robinson, Sharon Vetter, Fenglin Wang, Stephen Weathersby, Charles Yoneda, Martin Centurion & Xijie Wang .

    Affiliations

    Department of Physics and Astronomy, University of Nebraska-Lincoln, 855 N 16th Street, Lincoln, Nebraska 68588, USA
    Jie Yang, Matthew S. Robinson & Martin Centurion
    PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
    Markus Guehr
    Institute of Physics and Astronomy, Potsdam University, Potsdam 14476, Germany
    Markus Guehr
    SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
    Theodore Vecchione, Renkai Li, Nick Hartmann, Xiaozhe Shen, Ryan Coffee, Jeff Corbett, Alan Fry, Kelly Gaffney, Tais Gorkhover, Carsten Hast, Keith Jobe, Igor Makasyuk, Alexander Reid, Joseph Robinson, Sharon Vetter, Fenglin Wang, Stephen Weathersby, Charles Yoneda & Xijie Wang

    Contributions

    J.Y., M.G., T.V., M.S.R., R.L., X.S., T.G., F.W., S.W. and X.W. carried out the experiments. N.H., R. C., J.C., I.M., S.V. and A.F. developed the laser system. M.G. and J.Y. constructed the setup for gas phase experiments. C.H., K.J., A.R. and C.Y. helped on experimental setup. J.Y. performed the data analysis and simulations. The experiment was conceived by M.G., M.C. and X.W. The manuscript was prepared by J.Y., M.C., M.S.R. and M.G. with discussion and improvements from all authors. M.C. and X.W. supervised the work.

    See the full article here .

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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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  • richardmitnick 12:58 pm on April 4, 2016 Permalink | Reply
    Tags: , , SLAC LCLS, , ,   

    From SLAC: “Major Upgrade Will Boost Power of World’s Brightest X-ray Laser” 


    SLAC Lab

    April 4, 2016

    Construction begins today on a major upgrade to a unique X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory. The project will add a second X-ray laser beam that’s 10,000 times brighter, on average, than the first one and fires 8,000 times faster, up to a million pulses per second.

    The project, known as LCLS-II, will greatly increase the power and capacity of SLAC’s Linac Coherent Light Source (LCLS) for experiments that sharpen our view of how nature works on the atomic level and on ultrafast timescales.

    SLAC/LCLS
    SLAC/LCLS

    “LCLS-II will take X-ray science to the next level, opening the door to a whole new range of studies of the ultrafast and ultrasmall,” said LCLS Director Mike Dunne.

    SLAC/LCLS II schematic
    SLAC/LCLS II schematic

    “This will tremendously advance our ability to develop transformative technologies of the future, including novel electronics, life-saving drugs and innovative energy solutions.”

    SLAC Director Chi-Chang Kao said, “Our lab has a long tradition of building and operating premier X-ray sources that help users from around the world pursue cutting-edge research in chemistry, materials science, biology and energy research. LCLS-II will keep the U.S. at the forefront of X-ray science.”


    Access mp4 video here .
    This movie introduces LCLS-II, a future light source at SLAC. It will generate over 8,000 times more light pulses per second than today’s most powerful X-ray laser, LCLS, and produce an almost continuous X-ray beam that on average will be 10,000 times brighter. These unrivaled capabilities will help researchers address a number of grand challenges in science by capturing detailed snapshots of rapid processes that are beyond the reach of other light sources. (SLAC National Accelerator Laboratory)

    A Superior X-ray Microscope

    When LCLS opened six years ago as a DOE Office of Science User Facility, it was the first light source of its kind – a unique X-ray microscope that uses the brightest and fastest X-ray pulses ever made to provide unprecedented details of the atomic world.

    Hundreds of scientists use LCLS each year to catch a glimpse of nature’s fundamental processes in unprecedented detail. Molecular movies reveal how chemical bonds form and break; ultrafast snapshots capture electric charges as they rapidly rearrange in materials and change their properties; and sharp 3-D images of disease-related proteins provide atomic-level details that could hold the key for discovering potential cures.

    The new X-ray laser will work in parallel with the existing one, with each occupying one-third of SLAC’s 2-mile-long linear accelerator tunnel. Together they will allow researchers to make observations over a wider energy range, capture detailed snapshots of rapid processes, probe delicate samples that are beyond the reach of other light sources and gather more data in less time, thus greatly increasing the number of experiments that can be performed at this pioneering facility.

    “The upgrade will benefit X-ray experiments in many different ways, and I’m very excited to use the new capabilities for my own research,” said Brown University Professor Peter Weber, who co-led an LCLS study that used X-ray scattering to track ultrafast structural changes as ring-shaped gas molecules burst open in a chemical reaction vital to many processes in nature. “With LCLS-II, we’ll be able to bring the motions of atoms much more into focus, which will help us better understand the dynamics of crucial chemical reactions.”

    1
    The future LCLS-II X-ray laser (blue, at left) is shown alongside the existing LCLS (red, at right). LCLS uses the last third of SLAC’s 2-mile-long linear accelerator – a hollow copper structure that operates at room temperature and allows the generation of 120 X-ray pulses per second. For LCLS-II, the first third of the copper accelerator will be replaced with a superconducting one, capable of creating up to 1 million X-ray flashes per second. (SLAC National Accelerator Laboratory)

    A Big Leap in X-ray Laser Performance

    3
    This photo shows the prototype of a novel electron source for LCLS-II. Located at the future X-ray laser’s front end, it will produce bunches of electrons for the generation of X-ray pulses that are only quadrillionths of a second long, at rates of up to a million bunches per second. (R. Kaltschmidt/Berkeley Lab)

    Like the existing facility, LCLS-II will use electrons accelerated to nearly the speed of light to generate beams of extremely bright X-ray laser light. The electrons fly through a series of magnets, called an undulator, that forces them to travel a zigzag path and give off energy in the form of X-rays.

    But the way those electrons are accelerated will be quite different, and give LCLS-II much different capabilities.

    At present, electrons are accelerated down a copper pipe that operates at room temperature and allows the generation of 120 X-ray laser pulses per second.

    For LCLS-II, crews will install a superconducting accelerator. It’s called “superconducting” because its niobium metal cavities conduct electricity with nearly zero loss when chilled to minus 456 degrees Fahrenheit. Accelerating electrons through a series of these cavities allows the generation of an almost continuous X-ray laser beam with pulses that are 10,000 times brighter, on average, than those of LCLS and arrive up to a million times per second.

    4
    Electron bunches will gain energy in niobium cavities like these. Cooled to extremely low temperature, these “superconducting” cavities allow radiofrequency fields to boost electron energies without electrical resistance – a crucial property for the acceleration of electrons at a rate of up to a million bunches per second. (R. Hahn/Fermilab)

    In addition to a new accelerator, LCLS-II requires a number of other cutting-edge components, including a new electron source, two powerful cryoplants that produce refrigerant for the niobium structures, and two new undulators to generate X-rays.

    4
    This image shows a segment of an undulator magnet that will turn powerful beams of electrons into extremely bright X-ray light. Two undulators for generating low- and high-energy X-rays at SLAC’s future X-ray laser facility will consist of 21 and 32 segments, respectively. (R. Kaltschmidt/Berkeley Lab)

    6
    Illustration of the electron accelerator of SLAC’s future rapid-fire LCLS-II X-ray laser. No image credit

    Strong Partnerships for a Bright Future in X-ray Science

    6
    For LCLS-II, SLAC has teamed up with four other national labs – Argonne, Berkeley Lab, Fermilab and Jefferson Lab – and Cornell University, with each partner making key contributions to the many aspects of project planning as well as component design, acquisition and construction. (SLAC National Accelerator Laboratory)

    To make this major upgrade a reality, SLAC has teamed up with four other national labs – Argonne, Berkeley Lab, Fermilab and Jefferson Lab – and Cornell University, with each partner making key contributions to project planning as well as to component design, acquisition and construction.

    “We couldn’t do this without our collaborators,” said SLAC’s John Galayda, head of the LCLS-II project team. “To bring all the components together and succeed, we need the expertise of all partners, their key infrastructure and the commitment of their best people.”

    With favorable “Critical Decisions 2 and 3 (CD-2/3)” in March, DOE has formally approved construction of the $1 billion project, which is being funded by DOE’s Office of Science. SLAC is now clearing out the first third of the linac to make room for the superconducting accelerator, which is scheduled to begin operations in the early 2020s. In the meantime, LCLS will continue to serve the X-ray science community, except for a construction-related, six-month downtime in 2017 and a 12-month shutdown extending from 2018 into 2019.

    With the upgrades that are now moving forward, Dunne said, SLAC will have an X-ray laser facility that will enable groundbreaking research for years to come.

    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 9:23 pm on March 9, 2016 Permalink | Reply
    Tags: , SLAC LCLS, ,   

    From SLAC: “5 Ways SLAC’s X-ray Laser Can Change the Way We Live” 


    SLAC Lab

    March 9, 2016

    The First Five Years’ Points to a Bright Future of High-impact Discovery at LCLS

    SLAC LCLS
    LCLS

    SLAC LCLS-II line
    LCLS II

    If you’ve ever stood in a dark room wishing you had a flashlight, then you understand how scientists feel when faced with the mysteries of physical processes that happen at scales that are mind-bogglingly small and fast.

    The future of life-changing science – science that will spawn the electronic devices, medications and energy solutions of the future – depends on being able to see atoms and molecules at work.

    To do that you need special light – such as X-ray light with a wavelength as small as an atom – that pulses at the rate of femtoseconds. A femtosecond is to a second what a second is to 32 million years. It is the timescale for the basic building blocks of chemistry, biology and materials science.

    That’s why, six years ago, the Department of Energy’s SLAC National Accelerator Laboratory answered a bold call by the scientific community: Build a transformative tool for discovery, an X-ray laser so bright and fast it can unravel the hidden dynamics of our physical world.

    Since it began operation in 2009, this singularly powerful “microscope” has generated molecular movies, gotten a glimpse of the birth of a chemical bond, traced electrons moving through materials and made 3-D pictures of proteins that are key to drug discovery. Known to scientists as an X-ray free-electron laser (XFEL), SLAC’s Linac Coherent Light Source, or LCLS, is a DOE Office of Science User Facility that draws many hundreds of scientists from around the world each year to perform innovative experiments.

    The success of LCLS has inspired the spread of such machines all over the world.

    The latest issue of Reviews of Modern Physics contains the most comprehensive scientific overview of its accomplishments in a paper entitled, Linac Coherent Light Source: The First Five Years.

    LCLS staff scientists devoted about a year to compiling the collection of reports, says LCLS Director Mike Dunne.

    “We hope this extensive paper will be a valuable go-to source for this new field of science,” he said. “It describes many of the major accomplishments of the first X-ray laser of its kind. It also testifies to the power of this unique tool for scientific discovery that will benefit society in many ways.”

    Here are five ways SLAC’s X-ray laser and the science it enables can impact our future.

    1. Next-generation Computers and the Power Grid

    LCLS studies are helping to home in on the most promising materials and methods for transforming the electric power grid and driving next-generation computer components beyond classical limits.

    To make computers and other electronics faster and smaller, scientists need to understand and control materials’ magnetism and electronic behavior in new and more precise ways.

    LCLS has given us new, nanoscale views of how laser light rapidly flips the magnetic state of materials, providing new insight on how to write data with light. It has pinpointed the speed of electrical switching – such as what occurs in semiconductor transistors – with trillionth-of-a-second precision.

    Researchers at LCLS have also discovered a new, 3-D phenomenon that may be linked to high-temperature superconductivity, which allows some exotic materials to conduct electricity with zero resistance.

    2. Better, Cleaner Fuels and Chemicals

    The ability to take direct measurements of never-before-seen steps in chemical reactions is what scientists need to design more efficient reactions to produce fuels, fertilizers and industrial chemicals.

    While we know the starting ingredients and outcomes of chemical reactions, the early and middle steps are hard to see in real time at the atomic scale.

    LCLS X-ray pulses are so fast that they allow us to observe and analyze these previously unseen steps. They work like ultrabright flashes to capture X-ray snapshots of chemical reactions as they happen.

    Researchers have used LCLS to see new details of a reaction in catalytic converters that neutralizes pollution from car exhaust, and to produce “molecular movies” of a molecule transforming after one of its chemical bonds breaks.

    3. More Effective Medication with Fewer Side Effects

    Half of the medications on the market target special receptor proteins in the outer layer of our cells. To figure out how drugs work so we can make them more effective and reduce side effects, we need to see how they dock with these receptors in atom-by-atom detail.

    The best way to see how they fit is to form the protein-drug complexes into crystals and study them with X-rays, but many important samples don’t form big enough crystals or are too damage-prone for conventional X-ray tools. LCLS, though, can study very tiny crystals under more natural conditions, making it possible to determine the 3-D atomic structure of important proteins that had been out of reach.

    Already, LCLS has revealed a potential weakness in a protein involved in the transmission of African sleeping sickness, provided the best 3-D atomic-scale look at how blood pressure medicines and painkillers interact with receptors in our cells, and pinpointed the mechanism that allows our brain to send ultrafast chemical signals.

    In more recent studies, LCLS has also been used to image living bacteria that are responsible for generating the oxygen in our atmosphere, demonstrating an entirely new X-ray imaging technique.

    4. Renewable Energy that Mimics Nature

    LCLS allows us to study how plants use energy from sunlight to release oxygen into the air we breathe during a process called photosynthesis. The X-ray laser is uniquely capable of mapping the individual sunlight-triggered steps. Early data is already giving us a detailed understanding of photosynthesis – information that’s crucial for developing renewable, clean sources of energy that mimic nature.

    Scientists are also using the tool to study how light affects other living things. Just as sunlight can be life-giving, it can also be damaging. Studies at LCLS have revealed how our DNA protects itself from the sun’s ultraviolet rays and how proteins in bacteria and in our eyes shift shape in response to light.

    5. Fusion Reactions and Seeing Inside Planets

    High-power laser systems at SLAC heat matter to millions of degrees and crush it with billions of tons of pressure per square inch. Scientists use LCLS to measure what happens to matter under these extreme conditions with high precision at very small scales, and over very short periods of time.

    Some studies test the resilience of materials, such as those used in jet engines, to see how they fail. Others have simulated and studied the shock effects of meteorite impacts and have reproduced the conditions that are believed to exist at the heart of giant gas planets, which improves our understanding of how solar systems form.

    The results also give scientists new insight into how to replicate the fusion reactions that fuel our sun, an essential step in the pursuit of fusion energy as a power source.
    Looking to the Future

    “Many of the methods developed over the first years of LCLS operations responded to the needs of science to address vital areas of discovery that promise to have a significant impact on our lives,” Dunne emphasizes. “We expect that the coming years of XFEL innovation will push us further into the future, as we look ever deeper into the dynamics of our natural world.”

    “The Linac Coherent Light Source: The First Five Years,” was authored by a team representative of the X-ray and accelerator science groups at SLAC during this pioneering period of XFEL science: Christoph Bostedt, Sébastien Boutet, David M. Fritz, Zhirong Huang, Hae Ja Lee, Henrik T. Lemke, Aymeric Robert, William F. Schlotter, Joshua J. Turner and Garth J. Williams.

    Citation: Bostedt, et al., Reviews of Modern Physics, 9 March 2016 (10.1103/RevModPhys.88.015007).

    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 2:07 pm on February 10, 2016 Permalink | Reply
    Tags: , Biomolecules, , , SLAC LCLS,   

    From DESY: “New method opens crystal clear views of biomolecules” 

    DESY
    DESY

    2016/02/11
    No writer credit found

    A scientific breakthrough gives researchers access to the blueprint of thousands of molecules of great relevance to medicine and biology. The novel technique, pioneered by a team led by DESY scientist Professor Henry Chapman from the Center for Free-Electron Laser Science CFEL and reported this week in the scientific journal Nature, opens up an easy way to determine the spatial structures of proteins and other molecules, many of which are practically inaccessible by existing methods. The structures of biomolecules reveal their modes of action and give insights into the workings of the machinery of life. Obtaining the molecular structure of particular proteins, for example, can provide the basis for the development of tailor-made drugs against many diseases. “Our discovery will allow us to directly view large protein complexes in atomic detail,” says Chapman, who is also a professor at the University of Hamburg and a member of the Hamburg Centre for Ultrafast Imaging CUI.

    Dimer crystals Detec of complex biomolecules like that of the photosystem II molecule shown here
    Slightly disordered crystals of complex biomolecules like that of the photosystem II molecule shown here produce a complex continous diffraction pattern (right, the disorder is greatly exaggerated) under X-ray light that contains far more information than the so-called Bragg peaks of a strongly ordered crystal alone (left). Credit: DESY, Eberhard Reimann

    To determine the spatial structure of a biomolecule, scientists mainly rely on a technique called crystallography. The new work offers a direct route to “read” the atomic structure of complex biomolecules by crystallography without the usual need for prior knowledge and chemical insight. “This discovery has the potential to become a true revolution for the crystallography of complex matter,” says the chairman of DESY’s board of directors, Professor Helmut Dosch.

    In crystallography, the structure of a crystal and of its constituents can be investigated by shining X-rays on it. The X-rays scatter from the crystal in many different directions, producing an intricate and characteristic pattern of numerous bright spots, called Bragg peaks (named after the British crystallography pioneers William Henry and William Lawrence Bragg). The positions and strengths of these spots contain information about the structure of the crystal and of its constituents. Using this approach, researchers have already determined the atomic structures of tens of thousands of proteins and other biomolecules.

    But the method suffers from two significant barriers, which make structure determination extremely difficult or sometimes impossible. The first is that the molecules must be formed into very high quality crystals. Most biomolecules do not naturally form crystals. However, without the necessary perfect, regular arrangement of the molecules in the crystal, only a limited number of Bragg peaks are visible. This means the structure cannot be determined, or at best only a fuzzy “low resolution” facsimile of the molecule can be found. This barrier is most severe for large protein complexes such as membrane proteins. These systems participate in a range of biological processes and many are the targets of today’s drugs. Great skill and quite some luck are needed to obtain high-quality crystals of them.

    Extreme Sudoku in three dimensions

    The second barrier is that the structure of a complex molecule is still extremely difficult to determine, even when good diffraction is available. “This task is like extreme Sudoku in three dimensions and a million boxes, but with only half the necessary clues,” explains Chapman. In crystallography, this puzzle is referred to as the phase problem. Without knowing the phase – the lag of the crests of one diffracted wave to another – it is not possible to compute an image of the molecule from the measured diffraction pattern. But phases can’t be measured. To solve the tricky phase puzzle, more information must be known than just the measured Bragg peaks. This additional information can sometimes be obtained by X-raying crystals of chemically modified molecules, or by already knowing the structure of a closely-related molecule.

    When thinking about why protein crystals do not always “diffract”, Chapman realised that imperfect crystals and the phase problem are linked. The key lies in a weak “continuous” scattering that arises when crystals become disordered. Usually, this non-Bragg, continuous diffraction is thought of as a nuisance, although it can be useful for providing insights into vibrations and dynamics of molecules. But when the disorder consists only of displacements of the individual molecules from their ideal positions in the crystal then the “background” takes on a much more complex character – and its rich structure is anything but diffuse. It then offers a much bigger prize than the analysis of the Bragg peaks: the continuously-modulated “background” fully encodes the diffracted waves from individual “single” molecules.

    “If you would shoot X-rays on a single molecule, it would produce a continuous diffraction pattern free of any Bragg spots,” explains lead author Dr. Kartik Ayyer from Chapman’s CFEL group at DESY. “The pattern would be extremely weak, however, and very difficult to measure. But the ‘background’ in our crystal analysis is like accumulating many shots from individually-aligned single molecules. We essentially just use the crystal as a way to get a lot of single molecules, aligned in common orientations, into the beam.” With imperfect, disordered crystals, the continuous diffraction fills in the gaps and beyond the Bragg peaks, giving vastly more information than in normal crystallography. With this additional gain in information, the phase problem can be uniquely solved without having to resort to other measurements or assumptions. In the analogy of the Sudoku puzzle, the measurements provide enough clues to always arrive at the right answer.

    The best crystals are imperfect crystals

    This novel concept leads to a paradigm shift in crystallography — the most ordered crystals are no longer the best to analyse with the novel method. Instead, the best crystals are imperfect crystals. “For the first time we have access to single molecule diffraction – we have never had this in crystallography before,” he explains. “But we have long known how to solve single-molecule diffraction if we could measure it.” The field of coherent diffractive imaging, spurred by the availability of laser-like beams from X-ray free-electron lasers, has developed powerful algorithms to directly solve the phase problem in this case, without having to know anything at all about the molecule. “You don’t even have to know chemistry,” says Chapman, “but you can learn it by looking at the three-dimensional image you get.”

    To demonstrate their novel analysis method, the Chapman group teamed up with the group of Professor Petra Fromme from the Arizona State University (ASU), and other colleagues from ASU, University of Wisconsin, the Greek Foundation for Research and Technology – Hellas FORTH, and SLAC National Accelerator Laboratory in the U.S. They used the world’s most powerful X-ray laser LCLS at SLAC to X-ray imperfect microcrystals of a membrane protein complex called Photosystem II that is part of the photosynthesis machinery in plants.

    SLAC LCLS Inside
    Inside LCLS

    Including the continuous diffraction pattern into the analysis immediately improved the spatial resolution around a quarter from 4.5 Ångström to 3.5 Ångström (an Ångström is 0.1 nanometres). The obtained image gave fine definition of molecular features that usually require fitting a chemical model to see. “That is a pretty big deal for biomolecules,” explains co-author Dr. Anton Barty from DESY. “And we can further improve the resolution if we take more patterns.” The team had only a few hours of measuring time for these experiments, while full-scale measuring campaigns usually last a couple of days.

    The scientists hope to obtain even clearer and higher resolution images of photosystem II and many other macromolecules with their new technique. “This kind of continuous diffraction has actually been seen for a long time from many different poorly-diffracting crystals,” says Chapman. “It wasn’t understood that you can get structural information from it and so analysis techniques suppressed it. We’re going to be busy to see if we can solve structures of molecules from old discarded data.”

    Reference:
    Macromolecular diffractive imaging using imperfect crystals; Kartik Ayyer et al.; Nature (2016); DOI: 10.1038/nature16949

    See the full article here .

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    desi

    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 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 .

    Please help promote STEM in your local schools.

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    desi

    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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