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  • richardmitnick 3:06 pm on January 19, 2018 Permalink | Reply
    Tags: , , Fermilab delivers first cryomodule for ultrapowerful X-ray laser at SLAC, , , X-ray Technology   

    From FNAL: “Fermilab delivers first cryomodule for ultrapowerful X-ray laser at SLAC” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    January 19, 2018

    Science contact
    Rich Stanek
    rstanek@fnal.gov
    630-840-3519

    Media contact
    Andre Salles, Fermilab Office of Communication,
    asalles@fnal.gov
    630-840-6733

    A Fermilab team built and tested the first new superconducting accelerator cryomodule for the LCLS-II project, which will be the nation’s only X-ray free-electron laser facility.

    1
    The first cryomodule for SLAC’s LCLS-II X-ray laser departed Fermilab on Jan. 16. Photo: Reidar Hahn

    Earlier this week, scientists and engineers at the U.S. Department of Energy’s Fermilab in Illinois loaded one of the most advanced superconducting radio-frequency cryomodules ever created onto a truck and sent it heading west.

    Today, that cryomodule arrived at the U.S. DOE’s SLAC National Accelerator Laboratory in California, where it will become the first of 37 powering a three-mile-long machine that will revolutionize atomic X-ray imaging. The modules are the product of many years of innovation in accelerator technology, and the first cryomodule Fermilab developed for this project set a world record in energy efficiency.

    These modules, when lined up end to end, will make up the bulk of the accelerator that will power a massive upgrade to the capabilities of the Linac Coherent Light Source at SLAC, a unique X-ray microscope that will use the brightest X-ray pulses ever made to provide unprecedented details of the atomic world. Fermilab will provide 22 of the cryomodules, with the rest built and tested at the U.S. DOE’s Thomas Jefferson National Accelerator Facility in Virginia.

    The quality factor achieved in these components is unprecedented for superconducting radio-frequency cryomodules. The higher the quality factor, the lower the cryogenic load, and the more efficiently the cavity imparts energy to the particle beam. Fermilab’s record-setting cryomodule doubled the quality factor compared to the previous state-of-the-art.

    “LCLS-II represents an important technological step which demonstrates that we can build more efficient and more powerful accelerators,” said Fermilab Director Nigel Lockyer. “This is a major milestone for our accelerator program, for our productive collaboration with SLAC and Jefferson Lab and for the worldwide accelerator community.”

    Today’s arrival is merely the first. From now into 2019, the teams at Fermilab and Jefferson Lab will build the remaining cryomodules, including spares, and scrutinize them from top to bottom, sending them to SLAC only after they pass the rigorous review.

    “It’s safe to say that this is the most advanced machine of its type,” said Elvin Harms, a Fermilab accelerator physicist working on the project. “This upgrade will boost the power of LCLS, allowing it to deliver X-ray laser beams that are 10,000 times brighter than it can give us right now.”

    With short, ultrabright pulses that will arrive up to a million times per second, LCLS-II will further sharpen our view of how nature works at the smallest scales and help advance transformative technologies of the future, including novel electronics, life-saving drugs and innovative energy solutions. Hundreds of scientists use LCLS each year to catch a glimpse of nature’s fundamental processes.

    To meet the machine’s standards, each Fermilab-built cryomodule must be tested in nearly identical conditions as in the actual accelerator. Each large metal cylinder — up to 40 feet in length and 4 feet in diameter — contains accelerating cavities through which electrons zip at nearly the speed of light. But the cavities, made of superconducting metal, must be kept at a temperature of 2 Kelvin (minus 456 degrees Fahrenheit).

    2
    Thirty-seven cryomodules lined end to end — half from Fermilab and half from Jefferson Lab — will make up the bulk of the LCLS-II accelerator. Photo: Reidar Hahn

    To achieve this, ultracold liquid helium flows through pipes in the cryomodule, and keeping that temperature steady is part of the testing process.

    “The difference between room temperature and a few Kelvin creates a problem, one that manifests as vibrations in the cryomodule,” said Genfa Wu, a Fermilab scientist working on LCLS-II. “And vibrations are bad for linear accelerator operation.”

    In initial tests of the prototype cryomodule, scientists found vibration levels that were higher than specification. To diagnose the problem, they used geophones — the same kind of equipment that can detect earthquakes — to rule out external vibration sources. They determined that the cause was inside the cryomodule and made a number of changes, including adjusting the path of the flow of liquid helium. The changes worked, substantially reducing vibration levels — to a 10th of what they were originally — and have been successfully applied to subsequent cryomodules.

    Fermilab scientists and engineers are also ensuring that unwanted magnetic fields in the cryomodule are kept to a minimum, since excessive magnetic fields reduce the operating efficiency.

    “At Fermilab, we are building this machine from head to toe,” Lockyer said. “From nanoengineering the cavity surface to the integration of thousands of complex components, we have come a long way to the successful delivery of LCLS-II’s first cryomodule.”

    Fermilab has tested seven cryomodules, plus one built and previously tested at Jefferson Lab, with great success. Each of those, along with the modules yet to be built and tested, will get its own cross-country trip in the months and years to come.

    Read more about the LCLS-II project in SLAC’s press release.

    This project is supported by DOE’s Office of Science. LCLS is a DOE Office of Science user facility.

    See the full article here .

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    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

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  • richardmitnick 5:36 pm on January 10, 2018 Permalink | Reply
    Tags: , , , , , , , , , Organic chemistry, STXM-scanning transmission X-ray microscope, We’re looking at the organic ingredients that can lead to the origin of life” including the amino acids needed to form proteins, X-ray Technology   

    From LBNL: “Ingredients for Life Revealed in Meteorites That Fell to Earth” 

    Berkeley Logo

    Berkeley Lab

    January 10, 2018
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    1
    A blue crystal recovered from a meteorite that fell near Morocco in 1998. The scale bar represents 200 microns (millionths of a meter). (Credit: Queenie Chan/The Open University, U.K.)

    Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

    A detailed study of the chemical makeup within tiny blue and purple salt crystals sampled from these meteorites, which included results from X-ray experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), also found evidence for the pair’s past intermingling and likely parents. These include Ceres, a brown dwarf planet that is the largest object in the asteroid belt, and the asteroid Hebe, a major source of meteorites that fall on Earth.

    The study, published Jan. 10 in the journal Science Advances, provides the first comprehensive chemical exploration of organic matter and liquid water in salt crystals found in Earth-impacting meteorites. The study treads new ground in the narrative of our solar system’s early history and asteroid geology while surfacing exciting possibilities for the existence of life elsewhere in Earth’s neighborhood.

    “It’s like a fly in amber,” said David Kilcoyne, a scientist at Berkeley Lab’s Advanced Light Source (ALS), which provided X-rays that were used to scan the samples’ organic chemical components, including carbon, oxygen, and nitrogen.

    LBNL/ALS

    Kilcoyne was part of the international research team that prepared the study.

    While the rich deposits of organic remnants recovered from the meteorites don’t provide any proof of life outside of Earth, Kilcoyne said the meteorites’ encapsulation of rich chemistry is analogous to the preservation of prehistoric insects in solidified sap droplets.

    Queenie Chan, a planetary scientist and postdoctoral research associate at The Open University in the U.K. who was the study’s lead author, said, “This is really the first time we have found abundant organic matter also associated with liquid water that is really crucial to the origin of life and the origin of complex organic compounds in space.”

    She added, “We’re looking at the organic ingredients that can lead to the origin of life,” including the amino acids needed to form proteins.

    If life did exist in some form in the early solar system, the study notes that these salt crystal-containing meteorites raise the “possibility of trapping life and/or biomolecules” within their salt crystals. The crystals carried microscopic traces of water that is believed to date back to the infancy of our solar system – about 4.5 billion years ago.

    Chan said the similarity of the crystals found in the meteorites – one of which smashed into the ground near a children’s basketball game in Texas in March 1998 and the other which hit near Morocco in August 1998 – suggest that their asteroid hosts may have crossed paths and mixed materials.

    There are also structural clues of an impact – perhaps by a small asteroid fragment impacting a larger asteroid, Chan said.

    This opens up many possibilities for how organic matter may be passed from one host to another in space, and scientists may need to rethink the processes that led to the complex suite of organic compounds on these meteorites.

    “Things are not as simple as we thought they were,” Chan said.

    There are also clues, based on the organic chemistry and space observations, that the crystals may have originally been seeded by ice- or water-spewing volcanic activity on Ceres, she said.

    “Everything leads to the conclusion that the origin of life is really possible elsewhere,” Chan said. “There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system’s organic composition.”

    Chan said the two meteorites that yielded the 2-millimeter-sized salt crystals were carefully preserved at NASA’s Johnson Space Center in Texas, and the tiny crystals containing organic solids and water traces measure just a fraction of the width of a human hair. Chan meticulously collected these crystals in a dust-controlled room, splitting off tiny sample fragments with metal instruments resembling dental picks.

    2
    These ALS X-ray images show organic matter (magenta, bottom) sampled from a meteorite, and carbon (top). (Credit: Berkeley Lab)

    “What makes our analysis so special is that we combined a lot of different state-of-the-art techniques to comprehensively study the organic components of these tiny salt crystals,” Chan said.

    Yoko Kebukawa, an associate professor of engineering at Yokohama National University in Japan, carried out experiments for the study at Berkeley Lab’s ALS in May 2016 with Aiko Nakato, a postdoctoral researcher at Kyoto University in Japan. Kilcoyne helped to train the researchers to use the ALS X-ray beamline and microscope.

    The beamline equipped with this X-ray microscope (a scanning transmission X-ray microscope, or STXM) is used in combination with a technique known as XANES (X-ray absorption near edge structure spectroscopy) to measure the presence of specific elements with a precision of tens of nanometers (tens of billionths of a meter).

    “We revealed that the organic matter was somewhat similar to that found in primitive meteorites, but contained more oxygen-bearing chemistry,” Kebukawa said. “Combined with other evidence, the results support the idea that the organic matter originated from a water-rich, or previously water-rich parent body – an ocean world in the early solar system, possibly Ceres.”

    Kebukawa also used the same STXM technique to study samples at the Photon Factory, a research site in Japan. And the research team enlisted a variety of other chemical experimental techniques to explore the samples’ makeup in different ways and at different scales.

    Chan noted that there are some other well-preserved crystals from the meteorites that haven’t yet been studied, and there are plans for follow-up studies to identify if any of those crystals may also contain water and complex organic molecules.

    3
    Ceres, a dwarf planet in the asteroid belt pictured here in this false-color image, may be the source of organic matter found in two meteorites that crashed to Earth in 1998. (Credit: NASA)

    Kebukawa said she looks forward to continuing studies of these samples at the ALS and other sites: “We may find more variations in organic chemistry.”

    The Advanced Light Source is a DOE Office of Science User Facility.

    Scientists at NASA Johnson Space Center, Kochi Institute for Core Sample Research in Japan, Carnegie Institution of Washington, Hiroshima University, The University of Tokyo, the High-Energy Accelerator Research Organization (KEK) in Japan, and The Graduate University for Advanced Studies (SOKENDAI) in Japan also participated in the study. The work was supported by the U.S. DOE Office of Science, the Universities Space Research Association, NASA, the National Institutes of Natural Sciences in Japan, Japan Society for the Promotion of Science, and The Mitsubishi Foundation.

    See the full article here .

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  • richardmitnick 5:00 pm on January 3, 2018 Permalink | Reply
    Tags: , Bottom-up nanofabrication or molecular self-assembly, Center for Functional Nanomaterials(CFN), Directed self-assembly - combining the two approaches, Gregory Doerk at CFN, Lithography is generally faster–and more reliably produces the designed structures–but requires expensive complex tools, , , , , Self-assembly is often slower and less predictive but it is inexpensive and can be easier, Top-down nanofabrication, X-ray scattering experiments, X-ray Technology   

    From BNL- “CFN Scientist Spotlight: Gregory Doerk Guides the Self-Assembly of Materials to Make Diverse Nanoscale Patterns” 

    Brookhaven Lab

    December 7, 2017 [They just now put this up n social media.]
    Interview with a CFN scientist

    1
    Materials scientist Gregory Doerk in the materials processing lab at CFN.

    Some materials have the unique ability to self-assemble into organized molecular patterns and structures. Materials scientist Gregory Doerk of the Electronic Nanomaterials Group at the Center for Functional Nanomaterials (CFN)—a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory—takes advantage of this ability in materials called block copolymers. Using these self-assembling materials, which have chains of two or more distinct molecules linked together by chemical bonds, Doerk directs the formation of such patterns and structures at the nanoscale. The ultimate goal is to leverage these nanoscale architectures to control the properties of materials for applications including solar energy conversion and storage, catalysis, and optics.

    Self-assembly has gained a lot of attention recently as a nanofabrication approach. How does it differ from the approach that has been traditionally used?

    Broadly speaking, there are two platforms for nanofabrication. One platform is top-down nanofabrication, which is the traditional approach used to make computer chips and other microelectronics. Light is used to create patterns that are then carved into silicon wafers. The patterning technique using light is called optical lithography. The other approach is bottom-up nanofabrication, or molecular self-assembly. The properties of the materials are encoded in their weak interactions, which drive certain materials to come together and form specific configurations—kind of like Lego bricks but the bricks all build up on their own to form some structure.

    Lithography is generally faster–and more reliably produces the designed structures–but requires expensive, complex tools. Self-assembly is often slower and less predictive but it is inexpensive and can be easier. There are ways of combining the two approaches, and that combination is known as directed self-assembly. Self-assembling materials such as thin films of block copolymers are ordered using templates patterned by standard lithography. Directed self-assembly enhances current manufacturing processes, expanding the spectrum of pattern geometries that are possible, and lowers the cost of nanofabrication.

    Your self-assembly research is focused on block copolymers. What makes these materials so special?

    3
    The length of the polymer blocks (red and blue squiggly lines) and the strength of their interaction determine the shape of the resulting patterns in block copolymer self-assembly: (from left to right) spheres, cylinders, and lamellae (sheets).

    Since the 1950s, people have been using triblock copolymers (three polymers joined together) in materials like synthetic rubber. Most polymers will not mix. Trying to mix polymers is kind of like trying to mix oil and water.

    But in block copolymers, the polymer chains are chemically bound to each other. For example, diblock (two) copolymer chains are joined through a covalent bond. This bonding frustrates their drive to “demix.” Instead, if block copolymers are given energy to mobilize their chains—for example by annealing (heating) the polymer film on a hot plate to above its glass transition temperature (when a polymer transitions from a hard, glassy material to a soft, rubbery one)—the chains will reconfigure and assemble into nanoscale phase-separated domains. These domains are ordered into nanoscale patterns based on inherent traits of the block copolymer. For example, let us say we have two polymers, A and B, joined together (diblock copolymer). The length of block A relative to the length of both blocks, the overall length of the polymer chains, and the properties of the polymers and the strength of their interaction (how much the polymers want to pull apart) govern the size and morphology, or shape, of the resulting structures. If the chains are too short or their repulsive interactions are too weak, the polymers will mix, causing the ordered state to become a disordered state and thus no pattern will form.

    At CFN, a major part of our work is to transfer the patterns and structures made through self-assembly, electron-beam lithography, or optical lithography at our Nanofabrication Facility into other materials to control material properties. A great example of this is CFN Director Chuck Black’s work using block copolymers to create a self-assembled pattern that serves as a template for etching nanosized cones onto silicon surfaces. With these nanotextures, the silicon surfaces transformed from reflective mirrors to entirely black. That is one way we can use block copolymers.

    But we want to expand the range of things we can do with self-assembly—and thus the range of applications. Diversifying the patterns possible with block copolymer self-assembly is a big part of my research.

    Have you been able to expand this range?

    One way I am interested in expanding what we can do through self-assembly is by creating inorganic replicas of the self-assembled structures. We can accomplish this replication through a process called infiltration synthesis.

    4
    Plan view (top) and cross-sectional (bottom) scanning electron microscope images of an inorganic nanomesh created through iterative self-assembly and infiltration synthesis.

    For example, say you have a block copolymer that forms lamellae (stripes) perpendicular to a substrate. Using an atomic-layer-deposition tool, it is possible to infiltrate those lamellae with a metal oxide and then remove the polymer, leaving behind metal oxide lines in a pattern determined by the polymer self-assembly. It is even possible to perform self-assembly and replica formation on top of previous replicas in an iterative way. What is really interesting is that the topography from the initial layer actually acts as a template dictating how polymer domains in the next layer line up. In the case of a second layer of lamellae perpendicular with the substrate, a self-assembled nanomesh is naturally created.

    What other ways can you expand the range of self-assembled patterns?

    One area in which I have collaborated with other members of the Electronic Nanomaterials Group is to study the blending of block copolymers that form lamellae with block copolymers that form cylinders. The really cool thing we learned is that you can precisely control which of these two patterns emerge in different areas of a substrate through an approach we call selective directed self-assembly. In a diblock copolymer, one of the blocks may be relatively more hydrophobic (water repelling) and the other may be relatively more hydrophilic (water attracting). So if a chemical pattern was made up of alternating hydrophobic and hydrophilic lines, the block copolymer molecules would self-assemble accordingly. By changing the spacing and width of the chemical line gratings (patterns) on the substrate, we were able to direct the self-assembling blocks into specific arrangements—either forming striped patterns (lamellae) or hexagonal dot arrays (cylinders). We can locally adjust the spacing and linewidth of the underlying chemical template to precisely control exactly where these line or dot patterns form on the same substrate, too.

    How big are the features of these self-assembled nanoscale patterns?

    Block copolymers typically self-assemble into ordered periodic structures with a tunable repeat spacing between around 25 to 50 nanometers. Actually, one of the projects I am currently working on is to increase the size range over which block copolymers form patterns. There is a lot of work in the scientific community to go to smaller and smaller sizes (approaching a few nanometers) for lithographic applications such as making computer chips. But for certain applications, you need larger sizes.

    For example, the wavelength range of visible light is about 400 (purple) to 700 (red) nanometers. Even 400 nanometers is still about 10 times larger than the approximately 40-nanometer length scale possible with most block copolymers. As a result, light does not “see” the individual features of block copolymers.

    However, patterns with features closer to 200 nanometers in size can influence light in new ways, and I am working to scale block copolymer assembly to these sizes. One exciting application is using this approach to make “structural colors.” Colors are typically made using dyes or pigments. However, structural colors emerge from the way the light interacts with the nanomaterial—and so potentially one could make new types of lower-power displays through structural color.

    Unfortunately, the process of forming patterns from block copolymers slows drastically, and even stops altogether, for these larger sizes. The development of self-assembled patterns is impeded by defective structures that form at the start of self-assembly. For these defects to “heal,” the block polymer must reconfigure, which involves pulling one chain through the domain of the other polymer, overcoming a large energy barrier to do so. As the size of the polymers increases, the energy barrier goes up exponentially—so exponentially slower healing!

    Have you come up with any solutions to overcome this challenge?

    My colleagues and I found that blending small-molecular-weight homopolymers (polymers made up of the same type of molecules) with the block copolymers makes it easier for the block copolymer chains to move around. Adding homopolymers promotes dramatic increases in the size of well-ordered pattern areas, or “grains.” However, this addition alone does not let us form patterns with larger-size features from block copolymers. We also need to anneal the materials in a solvent vapor. Solvent vapor annealing involves putting a volatile solvent in the region of the diblock copolymer, causing the polymer film to swell. As the polymer film swells, the solvent molecules intersperse between polymer chains. This process has a plasticizing effect, making it easier for the polymer to move. So both mixing the block copolymer with a homopolymer and swelling it with a solvent are needed to speed the formation of large-scale patterns.

    5
    Without blending, the size of grains (single-color regions) of a diblock copolymer with a molecular weight of 36 kilograms/mole barely changes with thermal annealing over time (top row). Blending the block copolymer with homopolymers increases the grain size and speeds up the ordering process (bottom row).

    After annealing, we image the resulting patterns with scanning electron microscopes at CFN. We also perform x-ray scattering experiments at the Complex Materials Scattering beamline at Brookhaven Lab’s National Synchrotron Light Source II [also a DOE Office of Science User Facility] to get a measure of the periodicity during the annealing process so we can determine how quickly the material self-assembles into an ordered pattern.

    BNL NSLS-II

    BNL NSLS-II

    How do all of the different self-assembled patterns you generate translate to possible applications?

    6
    A comparison of scanning electron microscope images after solvent vapor annealing of a large block copolymer (top left) and the same copolymer with added homopolymer (top right) shows that the homopolymer can significantly improve pattern quality. The bottom image is a cross-sectional image of the top right sample.

    The work we do at CFN establishes the basis for producing new materials. For example, consider the mesh pattern I described. My colleague Chang-Yong Nam and I are working on making a mesh of zinc oxide nanowires through infiltration synthesis of block copolymers. Zinc oxide is a versatile semiconducting material, and these nanowires have a lot of surface area, making them attractive for a number of applications—including photoelectrochemical water splitting (a way of converting sunlight into fuel by splitting water into hydrogen and oxygen). These semiconducting nanowires are also very responsive to environmental cues like light or chemicals. Given their large area uniformity, the meshes could be easily integrated into widely deployable gas sensors.

    How did you come to join CFN?

    After graduate school, I completed a postdoctoral appointment working at IBM in California. It was there that I learned about block copolymers, using them to make patterns for microelectronics. I did that for three years, and then in 2013 I joined a research group at HGST, a subsidiary of Western Digital that sells hard disk and solid-state drives. At first, I worked on a project to create patterned nanoscale magnetic media onto which data is written to and read from, in order to enhance data density and stability.

    Following that project, I moved into another area that was not very research oriented. At about this time, the current CFN Director, Chuck Black, gave a talk at HGST. Chuck’s talk piqued my interest in CFN, and soon thereafter a position that very well fit my skills opened up. I applied, and joined CFN in 2015.

    What was it like coming from industry to a national lab setting?

    It definitely takes some getting used to. There is a lot less pressure in some ways but more pressure in other ways. At CFN, you are expected to develop a lot more on your own as far as what direction you need to pursue on the basis of what is valuable to the lab. In industry, the goals of the project are clear, and there are deliverables to keep you on the narrow path to achieving those goals. This is not to say that I did not do exploratory research for a portion of my time in industry.

    The other difference at CFN is that I am more involved with the academic and industrial community at large. I have to manage my time so that I can perform my own research and help users with their research. I find it really cool that researchers from all over the world come to CFN. The talent and expertise of the staff are what make the CFN so great. The staff know backwards and forwards what they are doing in the areas they specialize in, and they are dedicated to helping others.

    What are some of the ways you have helped users?

    I regularly show users how to do block copolymer self-assembly and the etching process to transfer patterns into a substrate. Some users have employed these patterns as superhydrophobic textures to manipulate the flow of liquids in microfluidic devices, for example. In many cases, I help users develop a process when they need self-assembled patterns of varying sizes or shapes, to be applied to different substrates.

    I also help with the lithographic patterning of unusual materials. For example, one user I am working with is trying to pattern protein hydrogels, looking at how they mechanically respond to swelling and de-swelling to understand how they might operate if injected into the body. Such protein hydrogels could have applications in biosensing, drug delivery, and wound healing.

    Some users are interested in solvent vapor annealing, which is a very tricky process to control. So I am building a system with feedback control that can be set to maintain a solvent fraction of any given solvent. Otherwise, if the amount of solvent varies over time, the self-assembly might not work at all (too little solvent) or result in a disordered state (too much solvent).

    How did you become interested in research?

    As an undergraduate at Case Western Reserve University, I majored in chemical engineering. One of my summer internships involved doing fuel cell work at a research lab. This internship led to another one at a fuel cell start-up, where I worked on sensors and solar cells. These internships gave me the opportunity to come up with ideas of my own and try different things. This exploration spurred me to pursue a doctoral degree at the University of California, Berkeley, where I continued my studies in chemical engineering.

    I also think my undergraduate studies in philosophy, which I minored in, gave me a new understanding of the way science works. I really enjoyed reading about the philosophy of science, including books like Kuhn’s The Structure of Scientific Revolutions. I learned how the views we often have are naïve or not accurate. There are lots of things people get wrong for a long time. But that does not mean they were not learning. Science is not perfect—but that is okay.

    I was not the kid who grew up knowing he wanted to be a scientist. I liked philosophy and delving into critical thought. But I began to realize there is a lot of commonality between philosophy and science—in both fields, the aim is to gain knowledge about the world around us. But science is better because you can actually test things!

    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 4:27 pm on January 3, 2018 Permalink | Reply
    Tags: , , , , , TPL-two-photon lithography, X-ray Technology   

    From LLNL: “Lab unlocks secrets of nanoscale 3D printing” 


    Lawrence Livermore National Laboratory

    Jan. 3, 2018
    Jeremy Thomas
    thomas244@llnl.gov
    925-422-5539

    1
    Through the two-photon lithography (TPL) 3D printing process, researchers can print woodpile lattices with submicron features a fraction of the width of a human hair. Image by Jacob Long and Adam Connell/LLNL.

    Lawrence Livermore National Laboratory (LLNL) researchers have discovered novel ways to extend the capabilities of two-photon lithography (TPL), a high-resolution 3D printing technique capable of producing nanoscale features smaller than one-hundredth the width of a human hair.

    The findings, recently published on the cover of the journal ACS Applied Materials & Interfaces , also unleashes the potential for X-ray computed tomography (CT) to analyze stress or defects noninvasively in embedded 3D-printed medical devices or implants.

    Two-photon lithography typically requires a thin glass slide, a lens and an immersion oil to help the laser light focus to a fine point where curing and printing occurs. It differs from other 3D-printing methods in resolution, because it can produce features smaller than the laser light spot, a scale no other printing process can match. The technique bypasses the usual diffraction limit of other methods because the photoresist material that cures and hardens to create structures — previously a trade secret — simultaneously absorbs two photons instead of one.

    2
    LLNL researchers printed octet truss structures with submicron features on top of a solid base with a diameter similar to human hair. Photo by James Oakdale/LLNL.

    In the paper, LLNL researchers describe cracking the code on resist materials optimized for two-photon lithography and forming 3D microstructures with features less than 150 nanometers. Previous techniques built structures from the ground up, limiting the height of objects because the distance between the glass slide and lens is usually 200 microns or less. By turning the process on its head — putting the resist material directly on the lens and focusing the laser through the resist — researchers can now print objects multiple millimeters in height. Furthermore, researchers were able to tune and increase the amount of X-rays the photopolymer resists could absorb, improving attenuation by more than 10 times over the photoresists commonly used for the technique.

    “In this paper, we have unlocked the secrets to making custom materials on two-photon lithography systems without losing resolution,” said LLNL researcher James Oakdale, a co-author on the paper.

    Because the laser light refracts as it passes through the photoresist material, the linchpin to solving the puzzle, the researchers said, was “index matching” – discovering how to match the refractive index of the resist material to the immersion medium of the lens so the laser could pass through unimpeded. Index matching opens the possibility of printing larger parts, they said, with features as small as 100 nanometers.

    “Most researchers who want to use two-photon lithography for printing functional 3D structures want parts taller than 100 microns,” said Sourabh Saha, the paper’s lead author. “With these index-matched resists, you can print structures as tall as you want. The only limitation is the speed. It’s a tradeoff, but now that we know how to do this, we can diagnose and improve the process.”

    3
    Through the two-photon lithography (TPL) 3D printing process, researchers can print woodpile lattices with submicron features a fraction of the width of a human hair. Photo by James Oakdale/LLNL.

    By tuning the material’s X-ray absorption, researchers can now use X-ray-computed tomography as a diagnostic tool to image the inside of parts without cutting them open or to investigate 3D-printed objects embedded inside the body, such as stents, joint replacements or bone scaffolds. These techniques also could be used to produce and probe the internal structure of targets for the National Ignition Facility, as well as optical and mechanical metamaterials and 3D-printed electrochemical batteries.

    The only limiting factor is the time it takes to build, so researchers will next look to parallelize and speed up the process. They intend to move into even smaller features and add more functionality in the future, using the technique to build real, mission-critical parts.

    “It’s a very small piece of the puzzle that we solved, but we are much more confident in our abilities to start playing in this field now,” Saha said. “We’re on a path where we know we have a potential solution for different types of applications. Our push for smaller and smaller features in larger and larger structures is bringing us closer to the forefront of scientific research that the rest of the world is doing. And on the application side, we’re developing new practical ways of printing things.”

    The work was funded through the Laboratory Directed Research and Development (LDRD) program. Other LLNL researchers who contributed to the project include Jefferson Cuadra, Chuck Divin, Jianchao Ye, Jean-Baptiste Forien, Leonardus Bayu Aji, Juergen Biener and Will Smith.

    See the full article here .

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  • richardmitnick 4:21 pm on December 29, 2017 Permalink | Reply
    Tags: Beamlne 28-ID-2 is one of the few places they could do their experiment, , , , , We’re already able to suggest several ways to improve scintillators and samples are being made by our collaborator for our group to study, X-ray imaging, X-ray Technology, X-rays can be harmful to patients if they are received in large or multiple doses   

    From BNL: “Scientists Solve Fundamental Puzzle in Medical Imaging” 

    Brookhaven Lab

    October 23, 2017
    Stephanie Kossman
    skossman

    1
    Researchers from Stony Brook University used the National Synchrotron Light Source II to characterize the physics of how light moves within scintillators. They’re the first group to directly measure this phenomenon. Adrian Howansky (center), a Ph.D. candidate at SBU’s Health Sciences Center, is shown holding one type of scintillator the group studied.

    Scientists from Stony Brook University (SBU) have used a novel technique at the National Synchrotron Light Source II (NSLS-II)—a U.S. Department of Energy (DOE) Office of Science User Facility located at Brookhaven National Laboratory—to answer longstanding questions in medical imaging.

    BNL NSLS-II

    BNL NSLS-II

    The research team used individual x-rays to characterize the physics of how light moves within scintillators—a component of x-ray detectors—for the very first time. Their findings could aid the development of more efficient x-ray detectors for improved medical diagnoses.

    X-ray imaging is a widespread technique for viewing the internal structures of matter. In the medical field, x-ray imaging is used to generate images of the body’s internal structure for diagnostic and interventional purposes. The method works by projecting x-rays though a patient and capturing them with an x-ray detector to produce a “shadow image” of the patient’s body. While x-ray imaging works similarly across all its applications, it presents a distinct problem to the medical industry.

    “There are competing challenges in medical x-ray imaging,” said Adrian Howansky, a Ph.D. candidate at SBU’s Health Sciences Center. “You want to detect as many x-rays as possible to produce a high-quality image and make the best diagnosis, but you also need to limit the number of x-rays you put through the patient to minimize their safety risk.”

    X-rays can be harmful to patients if they are received in large or multiple doses. That’s why the SBU team sought to optimize x-ray detectors by understanding the physics of how they work. If they could define the exact way these detectors produce an image, the team could identify methods for improving the images without increasing the number of x-rays sent through the patient. To do this, the scientists studied the most crucial component of the x-ray detector, called the scintillator. This material, whose thickness can be as little as 200 micrometers, is responsible for absorbing x-rays and turning them into bursts of visible light.

    “Up until our experiment here at NSLS-II, nobody has been able to precisely describe how light moves within scintillators to form an image,” Howansky said.

    2
    Adrian Howansky is pictured with equipment at NSLS-II’s x-ray powder diffraction beamline, where the Stony Brook group conducted their research. The team’s EMCCD camera is also shown.

    What scientists did know is that when light bounces around a scintillator before it is detected, it produces “blur” that reduces image resolution. Random variations in that blur can also contribute additional noise to the x-ray image. If this phenomenon could be directly observed and understood, scientists could identify ways to improve the performance of x-ray detectors and the quality of the images they produce—and reduce the number of x-rays needed to make usable images.

    The SBU team searched for the sources of this noise by analyzing different types of scintillators at beamline 28-ID-2 at NSLS-II. Using a novel approach, the scientists imaged individual x-rays at known points in the scintillator to eliminate confounding factors.

    “By putting single x-rays at precise depths inside of the scintillators, we were able to characterize exactly how light scatters and gets collected from different points of origin. This allows us to pinpoint each source of noise in the images that scintillators make,” Howansky said. “We’re the first group to be able to directly measure this phenomenon because of the resources at NSLS-II.”

    Rick Lubinsky, an assistant research professor in radiology at SBU, said, “It’s amazing what we are able to do with the help of beamline scientists at NSLS-II. They created the perfect x-ray beam for our research—just the right energy level and just the right shape. The beam was so thin that we could actually move it up and down inside of the scintillator and resolve what was happening. The brightness and intensity of the beam is incredible.”

    NSLS-II was one of the few places the SBU team could find the high spatial resolution and variable high-energy x-rays they needed to conduct their research. “But the proposal this team brought to NSLS-II was not within the scope of the beamline’s scientific program,” said Sanjit Ghose, the beamline scientist at 28-ID-2. “The irony is that this beamline is one of the few places they could do their experiment.” Ghose and Eric Dooryhee—the group leader for the scientific program that includes beamline 28-ID-2—worked hard to ensure the SBU team would be able to conduct this critically important research at NSLS-II. Ghose noted that other scientists whose research does not fit within the scientific programs at NSLS-II beamlines can reach out to the beamline scientists to discuss research opportunities and potentially test the feasibility of their experiments.

    3
    The Stony Brook team studies data with NSLS-II beamline scientist Sanjit Ghose. Pictured from left to right: Adrian Howansy, Rick Lubinsky, Wei Zhao, and Sanjit Ghose.

    “The arrangement of this user facility makes a lot of research possible that otherwise wouldn’t be,” said Wei Zhao, a professor of radiology and biomedical engineering at SBU.

    Now that the SBU team has gained fundamental knowledge of the physics of scintillators, they have already begun to research deeper questions, and are working with industry to produce the next generation of x-ray detectors.

    “The study has drawn attention from the medical community and our industrial collaborator that makes high resolution scintillators,” said Zhao. “We’re already able to suggest several ways to improve scintillators, and samples are being made by our collaborator for our group to study.”

    In addition to improving x-ray detectors for medical diagnoses, the results of this study [SPIE] could improve x-ray detectors across the board, including those for dental imaging, security imaging, and synchrotron science.

    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 3:57 pm on December 29, 2017 Permalink | Reply
    Tags: , , , , ISS-Inner-Shell Spectroscopy beamline, , Scientists have designed a new type of cathode that could make the mass production of sodium batteries more feasible, The ISS beamline was the first operational x-ray spectroscopy beamline at NSLS-II, X-ray Technology   

    From BNL: “Scientists Design Promising New Cathode for Sodium-based Batteries” 2017 

    Brookhaven Lab

    July 20, 2017
    Stephanie Kossman
    skossman

    1
    Xiao-Qing Yang (left) and Enyuan Hu (center) of Brookhaven’s Chemistry Department, pictured with beamline physicist Eli Stavitski (right) at the ISS beamline at NSLS-II.

    Scientists have designed a new type of cathode that could make the mass production of sodium batteries more feasible. Batteries based on plentiful and low-cost sodium are of great interest to both scientists and industry as they could facilitate a more cost-efficient production process for grid-scale energy storage systems, consumer electronics and electric vehicles. The discovery was a collaborative effort between researchers at the Institute of Chemistry (IOC) of Chinese Academy of Sciences (CAS) and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory.

    Lithium batteries are commonly found in consumer electronics such as smartphones and laptop computers, but in recent years, the electric vehicle industry also began using lithium batteries, significantly increasing the demand on existing lithium resources.

    “Just last year, the price of lithium carbonate tripled, because the Chinese electric vehicle market started booming,” said Xiao-Qing Yang, a physicist at the Chemistry Division of Brookhaven Lab and the lead Brookhaven researcher on this study.

    In addition, the development of new electrical grids that incorporate renewable energy sources like wind and solar is also driving the need for new battery chemistries. Because these energy sources are not always available, grid-scale energy storage systems are needed to store the excess energy produced when the sun is shining and the wind is blowing.

    Scientists have been searching for new battery chemistries using materials that are more readily available than lithium. Sodium is one of the most desirable options for researchers because it exists nearly everywhere and is far less toxic to humans than lithium.

    But sodium poses major challenges when incorporated into a traditional battery design. For example, a typical battery’s cathode is made up of metal and oxygen ions arranged in layers. When exposed to air, the metals in a sodium battery’s cathode can be oxidized, decreasing the performance of the battery or even rendering it completely inactive.

    The researchers at IOC of CAS and Jiangxi Normal University sought to resolve this issue by substituting different types of metals in the cathode and increasing the space between these metals. Then, using the Inner-Shell Spectroscopy (ISS) beamline at Brookhaven’s National Synchrotron Light Source II (NSLS-II)—a DOE Office of Science User Facility—Brookhaven’s researchers compared the structures of battery materials with unsubstituted materials to these new battery materials with substitute metals.

    “We use the beamline to determine how metals in the cathode material change oxidation states and how it correlates with the efficiency and lifetime of the battery’s structure,” says Eli Stavitski, a physicist at the ISS beamline.”

    The ISS beamline was the first operational x-ray spectroscopy beamline at NSLS-II. Here, researchers shine an ultra-bright x-ray beam through materials to observe how light is absorbed or reemitted. These observations allow researchers to study the structure of different materials, including their chemical and electronic states.

    The ISS beamline, which is specifically designed for high-speed experiments, allowed the researchers to measure real-time changes in the battery during the charge-discharge processes. Based on their observations made at the beamline, Brookhaven’s team discovered that oxidation was suppressed in the sodium batteries with substituted metals, indicating the newly designed sodium batteries were stable when exposed to air. This is a major step forward in enabling future mass production of sodium batteries.

    The researchers say this study[JACS] is the first of many that will use the ISS beamline at NSLS-II to advance the study of batteries.

    This study was supported by several Chinese research organizations, including the National Key R&D Program of China. The work at Brookhaven National Laboratory was supported by DOE’s Office of Energy Efficiency and Renewable Energy, the Vehicle Technology Office under Advanced Battery Material Research (BMR). DOE’s Office of Science (BES) also supports operations at NSLS-II.

    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 3:36 pm on December 29, 2017 Permalink | Reply
    Tags: -ray photoelectron and infrared reflection absorption spectroscopy, , , , , , , , We are the first team to trap a noble gas in a 2D porous structure at room temperature, X-ray Technology   

    From BNL: “Studying Argon Gas Trapped in Two-Dimensional Array of Tiny ‘Cages'” 

    Brookhaven Lab

    July 17, 2017
    Ariana Tantillo
    atantillo@bnl.gov
    (631) 344-2347

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

    Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation.

    1
    (Left to right) Anibal Boscoboinik, Jian-Qiang Zhong, Dario Stacchiola, Nusnin Akter, Taejin Kim, Deyu Lu, and Mengen Wang at Brookhaven Lab’s Center for Functional Nanomaterials (CFN). The team of scientists (including John Kestell and Alejandro Boscoboinik) carried out experiments at CFN, at Brookhaven’s National Synchrotron Light Source I and II, and in the Lab’s Chemistry Division to study the trapping of individual argon gas atoms (blue prop in Stacchiola’s hand) in two-dimensional (2D) nanoporous frameworks like the one Boscoboinik and Zhong are holding. They had been using these 2D frameworks as analogues to study catalysis in 3D porous materials called zeolites (structural model on the table), which speed up many important reactions such as the conversion of nitrogen-oxide emissions into nitrogen.

    Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory had just finished an experiment with a two-dimensional (2D) structure they synthesized for catalysis research when, to their surprise, they discovered that atoms of argon gas had gotten trapped inside the structure’s nanosized pores. Argon and other noble gases have previously been trapped in three-dimensional (3D) porous materials, but immobilizing them on surfaces had only been achieved by either cooling the gases to very low temperatures to condense them, or by accelerating gas ions to implant them directly into materials.

    “We are the first team to trap a noble gas in a 2D porous structure at room temperature,” said Anibal Boscoboinik, a materials scientist at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility where part of the research was conducted.

    This achievement, reported in a paper published today in Nature Communications, will enable scientists to use traditional surface-science tools—such as x-ray photoelectron and infrared reflection absorption spectroscopy—to perform detailed studies of single gas atoms in confinement. The knowledge gained from such research could inform the design, selection, and improvement of adsorbent materials and membranes for capturing gases such as radioactive krypton and xenon generated by nuclear power plants.

    The team of scientists from Brookhaven Lab, Stony Brook University, and the National University of San Luis in Argentina synthesized 2D aluminosilicate (composed of aluminum, silicon, and oxygen) films on top of a ruthenium metal surface. The scientists created this 2D model catalyst material to study the chemical processes happening in the industrially used 3D catalyst (called a zeolite), which has a cage-like structure with open pores and channels the size of small molecules. Because the catalytically active surface is enclosed within these cavities, it is difficult to probe with traditional surface-science tools. The 2D analogue material has the same chemical composition and active site as the 3D porous zeolite but its active site is exposed on a flat surface, which is easier to access with such tools.

    2
    An artistic rendering of an argon (Ar) atom trapped in a nanocage that has a silicon (Si)-oxygen (O) framework.

    To confirm that the argon atoms were trapped in these “nanocages,” the scientists exposed the 2D material to argon gas and measured the kinetic energy and number of electrons ejected from the surface after striking it with an x-ray beam. They performed these studies at the former National Synchrotron Light Source I (NSLS-I) and its successor facility, NSLS-II (both DOE Office of Science User Facilities at Brookhaven), with an instrument developed and operated by the CFN.

    BNL NSLS

    BNL NSLS-II

    BNL NSLS II

    Because the binding energies of core electrons are unique to each chemical element, the resulting spectra reveal the presence and concentration of elements on the surface. In a separate experiment conducted at the CFN, they grazed a beam of infrared light over the surface while introducing argon gas. When atoms absorb light of a specific wavelength, they undergo changes in their vibrational motions that are specific to that element’s molecular structure and chemical bonds.

    To get a better understanding of how the framework itself contributes to caging, the scientists investigated the trapping mechanism with silicate films, which are similar in structure to the aluminosilicates but contain no aluminum. In this case, they discovered that not all of the argon gets trapped in the cages—a small amount goes to the interface between the framework and ruthenium surface. This interface is too compressed in the aluminosilicate films for argon to squeeze in.

    After studying adsorption, the scientists examined the reverse process of desorption by incrementally increasing the temperature until the argon atoms completely released from the surface at 350 degrees Fahrenheit. They corroborated their experimental spectra with theoretical calculations of the amount of energy associated with argon entering and leaving the cages.

    In another infrared spectroscopy experiment conducted in Brookhaven’s Chemistry Division, they explored how the presence of argon in the cages affects the passage of carbon monoxide molecules through the framework. They found that argon restricts the number of molecules that adsorb onto the ruthenium surface.

    “In addition to trapping small atoms, the cages could be used as molecular sieves for filtering carbon monoxide and other small molecules, such as hydrogen and oxygen,” said first author Jian-Qiang Zhong, a CFN research associate.

    While their main goal going forward will be to continue investigating zeolite catalytic processes on the 2D material, the scientists are interested in learning the impact of different pore sizes on the materials’ ability to trap and filter gas molecules.

    “As we seek to better understand the material, interesting and unexpected findings keep coming up,” said Boscoboinik. “The ability to use surface-science methods to understand how a single atom of gas behaves when it is confined in a very small space opens up lots of interesting questions for researchers to answer.”

    This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility at Lawrence Berkeley National Laboratory, and was supported by Brookhaven’s Laboratory Directed Research and Development program and the National Scientific and Technical Research Council (CONICET) of Argentina.

    NERSC Cray XC40 Cori II supercomputer

    LBL NERSC Cray XC30 Edison supercomputer


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF


    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    See the full article here .

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    BNL Campus

    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 3:35 pm on December 28, 2017 Permalink | Reply
    Tags: Femtosecond X-ray lasers, Inelastic X-ray scattering, , , , , , X-ray Technology, XFELs   

    From Optics & Photonics: “X-Ray Studies Probe Water’s Elusive Properties” 

    Optics & Photonics

    28 December 2017
    Stewart Wills

    1
    Unlike most substances, liquid water is denser than its solid phase, ice. [Image: Stockholm University]

    In two different X-ray investigations, researchers have dug into some of the exotic properties of that most familiar of substances—water.

    In one study, researchers from Sweden, Japan and South Korea used a femtosecond X-ray laser to investigate the behavior of evaporatively supercooled liquid water, and to confirm the long-suspected view that water at low temperatures can exist in two different liquid phases (Science). In the other, a U.S.-Japanese team used high-resolution inelastic X-ray scattering to probe the dynamics of water molecules and how the liquid’s hydrogen bonds contribute to its unusual characteristics (Science Advances).

    Burst pipes and floating cubes

    Anyone who has confronted a burst water pipe on a frozen winter morning has firsthand knowledge of one of H20’s unusual characteristics. Whereas most substances increase in density as they go from a liquid to a solid state, water reaches its maximum density at 4°C, above its nominal freezing point of 0°C. That’s also the reason that the ice cubes float at the top of your water glass rather than sinking to the bottom.

    Grappling with this anomalous behavior, a research team at Boston University suggested around 25 years ago, based on computer simulations, that in a metastable, supercooled state, water might actually coexist in two liquid phases—a low-density liquid and a high-density liquid. Those two phases, the researchers proposed, merged into a single phase at a critical point in water phase diagram at around –44°C (analogous to the better-known critical point at a higher temperature between water’s liquid and gas phases).

    3
    Experiments using femtosecond X-ray free-electron lasers illuminated fluctuations between two different phases of liquid water—a high-density liquid (red) and a low-density liquid (blue)—as a function of temperature in the supercooled regime. [Image: Stockholm University]

    Actually getting liquid water to that frigid point has, however, seemed a bit of a pipe dream. While very pure liquid water can be rapidly supercooled to temperatures moderately below 0°C relatively easily, the proposed critical point lies far below that temperature range, in what researchers have dubbed a “no-man’s land” in which ice crystalizes much faster than the timescale of conventional lab measurements.

    Leveraging ultrafast lasers

    To move past that barrier, a research team led by Anders Nilsson of Stockholm University, Sweden, turned to the rapid timescales enabled by femtosecond X-ray free-electron lasers (XFELs). At XFEL facilities in Korea and Japan [un-named], the team sent a stream of tiny water droplets (approximately 14 microns in diameter) into a vacuum chamber, and fired the XFEL at the droplets at varying distances from the water-dispensing nozzle to obtain ultrafast X-ray scattering data.

    The tiny size of the droplets meant that as they traveled through the vacuum they rapidly evaporatively cooled—with the amount of cooling related to the time they spent in vacuum under a well-established formula. Thus, by taking X-ray measurements at varying distances from the nozzle, the researchers could examine the structural behavior of the liquid water at multiple temperatures in the deep-supercooling regime, near the hypothesized critical point. “We were able to X-ray unimaginably fast before the ice froze,” Nilsson said in a press release, “and could observe how it fluctuated” between the two hypothesized metastable phases of liquid water.

    The experiments allowed the team to flesh out the phase diagram of liquid water in a supercooled region previously thought to be inaccessible to experiment. And the researchers believe that the use of femtosecond XFELs to probe thermodynamic functions and structural changes at extreme states “can be generalized to many supercooled liquids.”

    Illuminating water’s dynamics

    4
    A team led by scientists at the U.S. Oak Ridge National Laboratory used inelastic X-ray scattering to visualize and quantify the movement of water molecules in space and time. [Image: Jason Richards/Oak Ridge National Laboratory, US Dept. of Energy]

    A second set of experiments, from researchers at the U.S. Oak Ridge National Laboratory, the University of Tennessee, and the SPring-8 synchrotron laboratory in Japan, looked at water’s dynamics at room temperature, using inelastic X-ray scattering (IXS).

    SPring-8 synchrotron, located in Hyōgo Prefecture, Japan

    The researchers illuminated these dynamics through a series of experiments in which they trained radiation from the SPring-8 facility’s high-resolution IXS beamline, BL35XU, onto a 2-mm-thick sample of liquid water. Through multiple scattering measurements across a range of momentum and energy-transfer values, the team was able to build a detailed picture of the so-called Van Hove function, which describes the probability of interactions between a molecule and its nearest neighbors as a function of distance and time.

    The team found that water’s hydrogen bonds behave in a highly correlated fashion with respect to one another, which gives liquid water its high stability and explains its viscosity characteristics. And, in a press release, the researchers further speculated that the techniques used here could be extended to studying the dynamics and viscosity of a variety of other liquids. Some of those studies, they suggested, could prove useful in “the development of new types of semiconductor devices with liquid electrolyte insulating layers, better batteries and improved lubricants.”

    Here, the research team was interested in sussing out how water molecules interact in real time, and how the strongly directional hydrogen bonds of water molecules work together to determine properties such the liquid’s viscosity.

    See the full article here .

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    Optics & Photonics News (OPN) is The Optical Society’s monthly news magazine. It provides in-depth coverage of recent developments in the field of optics and offers busy professionals the tools they need to succeed in the optics industry, as well as informative pieces on a variety of topics such as science and society, education, technology and business. OPN strives to make the various facets of this diverse field accessible to researchers, engineers, businesspeople and students. Contributors include scientists and journalists who specialize in the field of optics. We welcome your submissions.

     
  • richardmitnick 12:40 pm on December 18, 2017 Permalink | Reply
    Tags: , , Major Technology Developments Boost LCLS X-Ray Laser’s Discovery Power, , , X-ray Technology   

    From SLAC: “Major Technology Developments Boost LCLS X-Ray Laser’s Discovery Power” 


    SLAC Lab

    December 18, 2017
    Manuel Gnida

    1
    Smart computer programs improve the efficiency of X-ray laser operations and optimizations, allowing increased experimental time and potentially leading to new types of experiments. (Terry Anderson/SLAC National Accelerator Laboratory)

    Innovations at SLAC, including the world’s shortest X-ray flashes, ultra-high-speed pulse trains and smart computer controls, promise to take ultrafast X-ray science to a whole new level.

    Accelerator experts at the Department of Energy’s SLAC National Accelerator Laboratory are developing ways to make the most powerful X-ray laser better than ever. They have created the world’s shortest X-ray pulses for capturing the motions of electrons, as well as ultra-high-speed trains of X-ray pulses for “filming” atomic motion, and have developed “smart” computer programs that maximize precious experimental time.

    With its X-rays a billion times brighter than those available before, SLAC’s Linac Coherent Light Source (LCLS) has already revolutionized the field of ultrafast science and has opened new avenues for research in chemistry, biology and materials science. The new developments enhance the X-ray laser’s capabilities even further.

    SLAC/LCLS

    “Creating new capabilities for LCLS is a very important ongoing effort at SLAC,” said Axel Brachmann, head of the Linac and FEL Division of the lab’s Accelerator Directorate, at the 2017 SSRL/LCLS Users’ Meeting in September, where some of these developments were presented. “Our engineers and scientists are working hard to push the limits of what’s technologically possible and to make sure that SLAC stays a world leader in X-ray science.”

    Snapshots in Billionths of a Billionth of a Second

    3
    Two methods independently invented by scientists in SLAC’s Accelerator Directorate have produced the world’s first attosecond hard X-ray laser pulses at the lab’s LCLS facility. In one method, the shapes of electron bunches used to generate X-rays were manipulated with a radiofrequency field so that part of each bunch (dense area on the left) emits X-ray pulses with shorter-than-ever pulse lengths. (Yuantao Ding/SLAC National Accelerator Laboratory)

    LCLS’s discovery power is packed into extremely bright flashes of X-ray light, each lasting only a few femtoseconds – millionths of a billionth of a second. Like a strobe light that freezes motions too fast to see with the naked eye, these flashes capture images of atomic nuclei rapidly jiggling around in molecules and materials. But researchers would like to go further and film the even faster motions of an atom’s electrons.

    “These ultrafast motions are very fundamental because they set the stage for all the slower processes,” says staff scientist Yuantao Ding. “However, they occur in less than a femtosecond, and we need a faster ‘camera’ to capture them.”

    Two SLAC teams, led by Ding and fellow accelerator physicist Agostino Marinelli, have now made an important step in that direction. They demonstrated two independent methods for the generation of X-ray pulses of a few hundred attoseconds, or billionths of a billionth of a second, setting a record for X-ray lasers.

    Both groups manipulated the tightly packed bunches of electrons that fly through a special set of magnets, called an undulator, to generate LCLS X-ray pulses. They tweaked the bunches so only part of each bunch emitted X-ray laser light – resulting in a much shorter pulse length.

    “This is a major step forward, and actually uses relatively simple methods of generating attosecond pulses of X-rays with relatively high energy,” Marinelli says. “To take this even further, LCLS users want to use softer X-rays to allow them to study an atom’s outer electrons, which are the ones involved in chemical reactions. It turns out creating soft X-ray attosecond pulses is a much more complex process.”

    That’s why Marinelli and others are working on a third method, called X-ray Laser-Enhanced Attosecond Pulses (XLEAP). In this approach the electron bunches interact with an infrared laser inside the undulator and are chopped up into thin slices. Simulations suggest that this method, which is currently being tested at LCLS, can produce soft X-ray pulses that are only 500 attoseconds long.

    New Ways of Filming Atoms with Multiple X-ray Flashes

    4
    This illustration shows how three X-ray pulses with different energies, or colors, are generated with the fresh-slice technique from a single electron bunch traversing three separate sections of a special magnet, called an undulator. (Greg Stewart/SLAC National Accelerator Laboratory)

    To make movies of ultrafast processes at LCLS, researchers use the pump-probe technique, in which they hit a sample with a “pump” pulse from a conventional laser to trigger an atomic response and then examine the response with a “probe” pulse from the X-ray laser. By varying the amount of time between the two pulses, they can create a stop-action movie that shows how the sample’s atomic structure changes over time.

    This works well as long as the process, such as the breaking of a chemical bond in a molecule, can be initiated with a conventional laser emitting visible, infrared or ultraviolet light. However, some reactions can only be set off by the higher energies of X-ray light pulses.

    In principle, these experiments could be done at LCLS now, but the time between pulses would limit studies to processes slower than 8 milliseconds. Even with the future LCLS-II upgrade, which will “fire” up to a million pulses per second, this limit would still be a microsecond. Therefore, accelerator physicists are inventing methods that generate ultra-high-speed trains of X-ray flashes for the exploration of much faster processes.

    “SLAC is testing and implementing a number of multi-pulse techniques for X-ray pump-probe experiments with soft and hard X-rays, such as the split-undulator, twin-bunch, fresh-slice and two-bucket schemes,” says staff scientist Alberto Lutman. “Together they cover a broad range of very short pulse delays – from zero delay, meaning the pump and probe X-ray pulses hit the sample at the same time, to delays of just a few femtoseconds, and then all the way to more than 100 nanoseconds between pulses.”

    Lutman is spearheading the development of the fresh-slice technique, in which the head, tail and center of a single electron bunch can produce separate X-ray pulses in separate sections of the undulator. “This is an extremely flexible method,” he says. “It lets us finely vary the delay between the pulses, and it also allows us to tweak the color and polarization of each X-ray pulse individually.”

    Experiments with pulses of multiple colors, or X-ray energies, can, for example, enhance details in studies of the 3-D atomic structures and functions of molecules, such as medically important proteins. The fresh-slice method has also the potential to boost the power of extremely short X-ray pulses, and it has been used in seeding techniques that improve X-ray laser performance by making its light less noisy.

    Most of the multi-pulse methods have been demonstrated for rapid sequences of two or three X-ray flashes, but the use of even more pulses is on the horizon. A team led by accelerator physicist Franz-Josef Decker is currently working on a technique that uses multiple laser pulses for the generation of trains of up to eight X-ray pulses. This would allow researchers to follow the complex evolution of how a material responds to high-pressure shocks, for example in the study of meteorite collisions.

    ‘Smart’ Control of a Complex Discovery Machine

    Underpinning all of the above research is the need to find new ways of running LCLS in the most efficient way so more experiments can be accommodated. The facility is one of only five hard X-ray lasers operating in the world, and access to it is extremely competitive. One path to increasing the amount of experimental time is to minimize the time spent tuning the machine to meet the needs of specific experiments.

    “Each year we spend many hours optimizing the machine, which involves tedious adjustments of a large number of LCLS magnets,” says SLAC staff scientist Daniel Ratner. “We want to automate this procedure to free time for the activities that actually require human involvement.”

    Until about a year ago, he says, all fine-tuning was done manually. Now it’s done with the aid of computers, which has already cut the optimization time in half. But the lab’s accelerator experts want to take automation to the next level by using a type of artificial intelligence known as “machine learning” – an approach where “smart” computer programs learn from past X-ray laser optimizations instead of repeating the same routine every time.

    “This will lead to significant additional time savings,” says accelerator physicist Joseph Duris, who leads the machine learning initiative of SLAC’s Accelerator Directorate. “Smarter optimization algorithms will also help us explore completely new LCLS configurations to prepare for future experiments.”

    Last but not least, machine learning will help the lab efficiently operate two complex X-ray lasers side by side when the LCLS-II upgrade is complete.

    Financial support for this research was provided by the DOE Office of Science. Parts of these projects are supported by DOE’s Laboratory Directed Research and Development (LDRD) Program. To enhance LCLS performance and create new capabilities, SLAC’s Accelerator Directorate partners with X-ray instrument scientists of the LCLS Directorate and other groups across the lab, as well as with many members of the LCLS user community. LCLS is a DOE Office of Science user facility.

    See the full article here .

    Please help promote STEM in your local schools.

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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.

     
  • richardmitnick 10:55 pm on November 27, 2017 Permalink | Reply
    Tags: , , , SLAC-led Study Shows Potential for Efficiently Controlling 2-D Materials With Light, X-ray Technology   

    From SLAC: “SLAC-led Study Shows Potential for Efficiently Controlling 2-D Materials With Light” 


    SLAC Lab

    November 27, 2017
    Manuel Gnida

    In experiments with the lab’s ultrafast ‘electron camera,’ laser light hitting a material is almost completely converted into nuclear vibrations, which are key to switching a material’s properties on and off for future electronics and other applications.

    1
    Simulation of a laser pulse’s effect on two layers of molybdenum diselenide. (Hiroyuki Kumazoe/USC)

    Materials that are only a few atomic layers thick have generated a lot of excitement in recent years. These 2-D materials can have intriguing properties, such as extraordinary mechanical strength and superior electrical and heat conductivity, and could benefit a number of next-generation applications, including flexible electronics, data storage devices, solar cells, light-emitting diodes and chemical catalysts. Researchers also think they may be able to customize the properties of these materials by using light pulses to rapidly switch them from one state, or phase, to another, for example from an insulating to a conducting state.

    However, the ability to do this depends on how efficiently the light’s energy is transferred to the material’s atomic nuclei. Now, a team led by researchers from the Department of Energy’s SLAC National Accelerator Laboratory has demonstrated for the first time that the energy transfer is very fast and extremely efficient.

    “Our data show that essentially all of the light energy gets converted into vibrations of the material’s atomic nuclei within a trillionth of a second,” says SLAC’s Ming-Fu Lin, the lead author of a study published Nov. 23 in Nature Communications. “This efficient energy conversion is crucial, because those nuclear motions can initiate what we call a phase transition in the material – a change that alters its properties.”

    The researchers looked at a sample made of two layers of molybdenum diselenide – a model system for 2-D materials that can potentially be switched from a semiconducting state to a metal state and vice versa. They first hit the sample with a very brief laser pulse and then observed how its energy spread into the material over time with SLAC’s ultrafast “electron camera” – an apparatus for ultrafast electron diffraction (UED) that uses a highly energetic electron beam to probe a sample’s atomic structure and nuclear motions.

    “UED is a powerful tool for studies of these very thin 2-D materials,” says SLAC staff scientist Xiaozhe Shen, a co-author of the paper. “The technique yields relatively strong signals, high spatial resolution, and it nicely complements X-ray laser studies in making movies of a material’s atomic structure.”

    Although the researchers didn’t see a phase transition in molybdenum diselenide, their results help them better understand the energy transfer from the laser light to the material.

    “It’s an important first step toward designing 2-D materials that we can control with light,” Lin says. “The next steps will be to find out if we can see light-induced phase transitions in other materials and if we can make materials whose properties we can alter in a controlled way by steering phase transitions in particular directions.”

    The results are also used for the validation of novel software developed by the Materials Genome Innovation for Computational Software (MAGICS) center, led by the University of Southern California, Los Angeles. Another MAGICS partner involved in the study was Rice University, where the 2-D material was synthesized.

    “Similar to biological genome projects that want to find out everything about the genomes of organisms, our goal is to learn everything about materials and to develop computational tools that allow us to make accurate predictions of material properties,” says SLAC’s Uwe Bergmann, the center’s associate director for validation and the principal investigator of the study. “MAGICS brings together researchers who develop advanced computer code, who take on the challenging synthesis of 2-D materials, and who provide the experimental data needed for testing the computer models. At SLAC, we’re doing UED experiments and ultrafast X-ray studies, but without the center’s team effort, this work wouldn’t be possible.”

    Experiments for this study were carried out by researchers from SLAC’s Linac Coherent Light Source (LCLS),

    SLAC/LCLS

    a DOE Office of Science User Facility; the Stanford PULSE Institute, which is jointly operated by SLAC and Stanford University; and the lab’s Accelerator Directorate. Samples came from Rice University, and computer simulations were done at USC. Additional MAGICS partners not involved in this study are DOE’s Lawrence Berkeley National Laboratory, the University of Missouri and the California Institute of Technology. The study was funded by the DOE Office of Science and the National Science Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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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