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  • richardmitnick 6:49 pm on September 23, 2020 Permalink | Reply
    Tags: "New Molecules from GOTHAM", , An Attack from All Angles, , , , Chemistry, , Hiding in Slow Motion, The Search for New Chemistry   

    From AAS NOVA: “New Molecules from GOTHAM” 

    AASNOVA

    From AAS NOVA

    23 September 2020
    Susanna Kohler

    1
    Infrared view of the Taurus Molecular Cloud complex captured with Herschel. [ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech).]

    ESA/Herschel spacecraft active from 2009 to 2013.

    What as-yet unidentified molecules lurk in the dark clouds of our nearby universe? Answering this requires observation, experiment, and theory — and GOTHAM is on the case.

    The Search for New Chemistry

    2
    Another view of the Taurus Molecular Cloud, captured here in millimeter wavelengths by the APEX telescope. [ESO.]

    ESO/MPIfR APEX high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft).

    In the census of the molecular makeup of our universe, the interstellar medium (ISM) is the best target for diversity: we’ve spotted just over 200 different molecules in our galaxy’s ISM. We expect that there are many more out there, however — and identifying where these different molecules are found will help us to understand when and how they form.

    To this end, a team of scientists is undertaking the GOTHAM project [GBT Observations of TMC-1: Hunting Aromatic Molecules]: a radio search of a cold, dark cloud located 450 light-years away called the Taurus Molecular Cloud 1 (TMC-1). This chilly cloud has not yet collapsed to form a star, providing us with an opportunity to identify new molecules that are able to form in a cold, pre-stellar environment.

    Hiding in Slow Motion

    Green Bank Radio Telescope, West Virginia, USA, now the center piece of the GBO, Green Bank Observatory, being cut loose by the NSF, supported by Breakthrough Listen.

    But the hunt for molecules in a cold, dark cloud is challenging! We generally identify molecules by searching for their signature transition lines in ISM spectra. But in cold clouds, molecules aren’t moving much, which makes their spectral lines very narrow. This means that we need extremely high-spectral-resolution telescopes to be able to identify them. Fortunately, GOTHAM leverages the 100-meter Green Bank Telescope (GBT), which is up to the task!

    In a new article led by Brett McGuire (MIT, NRAO, and Center for Astrophysics | Harvard & Smithsonian), a team of scientists details the GOTHAM project and its early science results. This is just one of six new articles that describe the first molecular detections by GOTHAM.

    An Attack from All Angles

    How does a new molecular detection work? As an example, we can look at GOTHAM’s discovery of propargyl cyanide (HCCCH2CN) in TMC-1.

    First, due to the GBT’s high spectral resolution, the team needed to produce new, fine-detail guides for the forest of spectral lines expected from propargyl cyanide. This required new laboratory measurements of the molecule.

    4
    Individual line detections of propargyl cyanide in the GOTHAM data. [McGuire et al. 2020.]

    Next, the team had to search for these lines in the GBT data. Propargyl cyanide has 3,700 transitions that fall within GOTHAM’s observing range, all contributing to the total flux seen for this molecule. Teasing out these signatures requires complex data analysis.

    Finally, after achieving a significant detection of the molecule, the team had to do a sanity check. They conducted simulations of TMC-1 using astrochemical codes and included different channels that could form and destroy propargyl cyanide. They then checked that the abundances they measured for this molecule matched expectations from the simulations.

    More Discoveries Ahead

    This multi-faceted process has already led to a number of new detections in addition to propargyl cyanide. The detections are announced across a set of six articles — including an additional ApJ Letters publication, in which Ci Xue (University of Virginia, Charlottesville) and collaborators detail the first astronomical detection of isocyanodiacetylene (HC4NC) and the implications for how this molecule and others like it form in the ISM.

    What’s more, all of these new results still only make up 30% of the eventual data that will be collected for the GOTHAM project. There’s plenty more to look forward to in the future as we continue to expand our understanding of the chemistry of the universe around us.

    Citation

    “Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH2CN) in TMC-1,” Brett A. McGuire et al 2020 ApJL 900 L10.
    https://iopscience.iop.org/article/10.3847/2041-8213/aba632

    “Detection of Interstellar HC4NC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 Conditions,” Ci Xue et al 2020 ApJL 900 L9 [above].

    See the full article here .


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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 5:19 pm on September 15, 2020 Permalink | Reply
    Tags: "Quantum computer models a chemical reaction", , Chemistry, Google’s superconducting processor simulates molecules with the help of a classical computer and a method to deal with errors., , The Hartree–Fock method   

    From Physics Today: “Quantum computer models a chemical reaction” 

    Physics Today bloc

    From Physics Today

    8 Sep 2020
    Heather Hill

    Google’s superconducting processor simulates molecules with the help of a classical computer and a method to deal with errors.

    Google 54-qubit Sycamore superconducting processor quantum computer.

    The Google AI Quantum team made a big media splash a year ago when it announced quantum supremacy [Nature], the point at which a quantum device can solve a problem that a classical computer can’t in a reasonable time frame. But quantum computing still faces many challenges before it becomes practical. As academic and industrial researchers work to increase the number of qubits, reduce error rates, and find more effective error-mitigation strategies, they’ve also become interested in near-term quantum devices, which work with current capabilities.

    In that spirit, the Google team has now applied its 54-qubit Sycamore superconducting processor, shown in the above photo, to chemistry simulations. The researchers are the first to include a quantum computer in the modeling of a chemical reaction, and their Hartree–Fock calculations are a performance yardstick for a combined quantum and classical computation.

    The Hartree–Fock method assumes that the wavefunction for a system of electrons can be written in terms of single-electron functions, without electron–electron interactions, and that each electron feels the average electric field from other electrons. The wavefunction is then adjusted to minimize its energy.

    In the Google team’s calculations, each qubit represents a single-electron wavefunction, or orbital. The researchers apply a series of rotation logic gates to effectively rewrite the system’s wavefunction as a sum of those orbitals. The qubits’ degrees of excitation—between 0 and 1—indicate the probability that each orbital is filled. The wavefunction’s energy is measured and fed into a classical computer, which sets new rotation parameters for the gates. The parameters are repeatedly tweaked to find the minimum energy.

    The researchers used that method for two common electronic-structure benchmarks: distinguishing the pathways for a diazene molecule, HNNH, to transform between cis and trans isomers and finding the binding energy of stretched linear hydrogen chains for lengths of 6, 8, 10, and 12 atoms. Previous electronic-structure calculations by quantum computers required only up to 6 qubits, but here the researchers used as many as 12 qubits interacting through 72 two-qubit logic gates.

    With all those qubits and gates, error mitigation was essential. The team kept only measurements in which the number of particles stayed the same; a change in that number is a clear sign of an error. The researchers also looked at the one-particle densities, and if the wavefunction didn’t yield the expected 0 and 1 eigenvalues, they projected it onto the closest state that did. They were able to get an accuracy that was high enough to make chemical predictions with 99% fidelity for the logic gates and 97% fidelity for readout.

    Science paper:
    Hartree-Fock on a superconducting qubit quantum computer
    Science

    See the full article here .

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    “Our mission

    The mission of Physics Today is to be a unifying influence for the diverse areas of physics and the physics-related sciences.

    It does that in three ways:

    • by providing authoritative, engaging coverage of physical science research and its applications without regard to disciplinary boundaries;
    • by providing authoritative, engaging coverage of the often complex interactions of the physical sciences with each other and with other spheres of human endeavor; and
    • by providing a forum for the exchange of ideas within the scientific community.”

     
  • richardmitnick 2:46 pm on September 15, 2020 Permalink | Reply
    Tags: "Growing metallic crystals in liquid metal", , Chemistry, Fleet ARC Center of Excellence AU, , , , , The researchers at at the University of New South Wales (UNSW) School of Chemical Engineering looked at liquid metals from a different angle.   

    From Fleet ARC Center of Excellence AU via phys.org: “Growing metallic crystals in liquid metal” 

    From Fleet ARC Center of Excellence AU

    via


    From phys.org

    1
    Experimental set up. Credit: FLEET.

    Imagine an alien world with oceans of liquid metal.

    If such a world exists, metallic elements are likely the sources of the dissolved materials and particles in these oceans. Everything would be made of metallic elements, even lifeforms.

    It may sound like a concept pulled straight out of a science fiction movie, but some basic elements of this fantastical vision can still be easily realized on our planet.

    We are all familiar with growing crystals in water. The most obvious example is the growth of sugar crystals that many of us have done during our time at school. Here, sugar solute in a water solvent can precipitate as crystals out of the solution.

    Now, Australian researchers have shown the possibility of an analogous observation with liquid metals as a solvent and published an exciting report in the journal ACS Nano.

    It is known that metallic elements can dissolve and form solutes in liquid metal solvents. It is also known that these secondary metals can form clusters of metallic crystals inside the metallic solvent. This is in fact the base of the well-established field of metallurgy. However, in metallurgy the primary interest is in solidifying solvents and solutes together to create solid alloys for a variety of applications.

    The researchers at at the University of New South Wales (UNSW), School of Chemical Engineering looked at liquid metals from a different angle.

    They used gallium, which is liquid at near room temperature, like mercury, and dissolved different metals into it.

    Small crystals of these metallic elements formed inside the liquid metal.

    However, as the surface tension of liquid metal is quite high, these metallic crystals remained trapped inside the liquid metals.

    High surface tension means that liquid metals are immiscible in other liquids and as such it is not possible for the metallic crystals to naturally free themselves into the surrounding.

    The researchers discovered a new method to extract these metallic crystals out of the liquid alloy. By applying a voltage to the surface of a liquid metal droplet, they were able to reduce the surface tension sufficiently to allow the metallic crystals to be pulled out.

    “We were able to make very small crystals that were of a metallic and metal oxide nature,” said Dr. Mohannad Mayyas, author of the paper. “We dissolved indium, tin, and zinc into gallium liquid and precipitated them out of the media by applying a voltage in a specific set-up. The method is really advantageous as making such crystals generally requires hazardous precursors and harsh synthesis conditions.”

    “Other researchers can continue our work and explore the many possibilities that liquid metal solvents offer,” suggested Prof Kourosh Kalantar-Zadeh, the corresponding author of the paper. “For example, liquid metals are super catalytic. While the formation of crystals in aqueous solutions may take a long time, the creation of the metallic elements inside liquid metal can take place instantly. Additionally, liquid metals offer opportunities for intriguing interfacial chemistry that do not exist for any other systems.”

    See the full article here.

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    FLEET addresses a grand challenge: reducing the energy used in information technology, which now accounts for 8% of the electricity use on Earth, and is doubling every 10 years.

    The current, silicon-based technology will stop becoming more efficient in the next decade as Moore’s law comes to an end.

    FLEET is the ARC Centre of Excellence in Future Low-Energy Electronics Technologies

     
  • richardmitnick 1:45 pm on September 15, 2020 Permalink | Reply
    Tags: "Elements of surprise: Neutron stars contribute little but something's making gold research finds", All the hydrogen in the universe—including every molecule of it on Earth—was created in the Big Bang which also produced a lot of helium and lithium but not much else., , ARC Centres of Excellence for All Sky Astrophysics in 3D AU, , , , Chemistry, , Current models can't explain the amount of gold in the cosmos—creating an astronomical mystery., Neutron star collisions do not create the quantity of chemical elements previously assumed a new analysis of galaxy evolution finds., Neutron star mergers did not produce enough heavy elements in the early life of the universe and they still don't now 14 billion years later., , , Researchers found that heavy elements needed to be created by unusual supernovae that collapse while spinning at high speed and generating strong magnetic fields., Silver is over-produced but gold is under-produced in the model compared with observations., The new modeling the researchers say will substantially change the presently accepted model of how the universe evolved., The rest of the naturally occurring elements are made by nuclear processes happening inside stars., We built this new model to explain all elements at once and found enough silver but not enough gold.   

    From ARC Centres of Excellence for All Sky Astrophysics in 3D AU: “Elements of surprise: Neutron stars contribute little, but something’s making gold, research finds” 

    arc-centers-of-excellence-bloc

    From ARC Centres of Excellence for All Sky Astrophysics in 3D AU

    1
    The Periodic Table, showing naturally occurring elements up to uranium. Shading indicates stellar origin. Credit: Content: Chiaki Kobayashi et al Artwork: Sahm Keily.

    Periodic Table 2014 NIST. For comparison.

    Neutron star collisions do not create the quantity of chemical elements previously assumed, a new analysis of galaxy evolution finds. The research also reveals that current models can’t explain the amount of gold in the cosmos—creating an astronomical mystery. The work has produced a new-look Periodic Table showing the stellar origins of naturally occurring elements from carbon to uranium.

    All the hydrogen in the universe—including every molecule of it on Earth—was created in the Big Bang, which also produced a lot of helium and lithium, but not much else. The rest of the naturally occurring elements are made by nuclear processes happening inside stars. Mass governs exactly which elements are forged, but they are all released into galaxies in each star’s final moments—explosively, in the case of really big ones, or as dense outflows, similar to solar wind, for ones in the same class as the sun.

    “We can think of stars as giant pressure cookers where new elements are created,” explained co-author Associate Professor Karakas from Australia’s ARC Center of Excellence for All Sky Astrophysics in Three Dimensions (ASTRO 3-D).

    “The reactions that make these elements also provide the energy that keeps stars shining brightly for billions of years. As stars age, they produce heavier and heavier elements as their insides heat up.”

    Half of all the elements that are heavier than iron—such as thorium and uranium—were thought to be made when neutron stars, the superdense remains of burnt-out suns, crashed into one another. Long theorized, neutron star collisions were not confirmed until 2017. Now, however, fresh analysis by Karakas and fellow astronomers Chiaki Kobayashi and Maria Lugaro reveals that the role of neutron stars may have been considerably overestimated—and that another stellar process altogether is responsible for making most of the heavy elements.

    “Neutron star mergers did not produce enough heavy elements in the early life of the universe, and they still don’t now, 14 billion years later,” said Karakas. “The universe didn’t make them fast enough to account for their presence in very ancient stars, and, overall, there are simply not enough collisions going on to account for the abundance of these elements around today.”

    Instead, the researchers found that heavy elements needed to be created by an entirely different sort of stellar phenomenon—unusual supernovae that collapse while spinning at high speed and generating strong magnetic fields. The finding is one of several to emerge from their research, which has just been published in The Astrophysical Journal. Their study is the first time that the stellar origins of all naturally occurring elements from carbon to uranium have been calculated from first principles.

    The new modeling, the researchers say, will substantially change the presently accepted model of how the universe evolved.”For example, we built this new model to explain all elements at once, and found enough silver but not enough gold,” said co-author Associate Professor Kobayashi, from the University of Hertfordshire in the UK.

    “Silver is over-produced but gold is under-produced in the model compared with observations. This means that we might need to identify a new type of stellar explosion or nuclear reaction.” The study refines previous studies that calculate the relative roles of star mass, age and arrangement in the production of elements. For instance, the researchers established that stars smaller than about eight times the mass of the sun produce carbon, nitrogen and fluorine, as well as half of all the elements heavier than iron. Massive stars over about eight times the sun’s mass that also explode as supernovae at the end of their lives produce many of the elements from carbon through to iron, including most of the oxygen and calcium needed for life.

    “Apart from hydrogen, there is no single element that can be formed only by one type of star,” explained Kobayashi.

    “Half of carbon is produced from dying low-mass stars, but the other half comes from supernovae. And half the iron comes from normal supernovae of massive stars, but the other half needs another form, known as Type Ia supernovae. These are produced in binary systems of low mass stars.”

    Pairs of massive stars bound by gravity, in contrast, can transform into neutron stars. When these smash into each other, the impact produces some of the heaviest elements found in nature, including gold.

    On the new modeling, however, the numbers simply don’t add up.

    “Even the most optimistic estimates of neutron star collision frequency simply can’t account for the sheer abundance of these elements in the universe,” said Karakas. “This was a surprise. It looks like spinning supernovae with strong magnetic fields are the real source of most of these elements.”

    Co-author Dr. Maria Lugaro, who holds positions at Hungary’s Konkoly Observatory and Australia’s Monash University, thinks the mystery of the missing gold may be solved quite soon. “New discoveries are to be expected from nuclear facilities around the world, including Europe, the U.S. and Japan, currently targeting rare nuclei associated with neutron star mergers,” she said. “The properties of these nuclei are unknown, but they heavily control the production of the heavy element abundances. The astrophysical problem of the missing gold may indeed be solved by a nuclear physics experiment.”

    The researchers concede that future research might find that neutron star collisions are more frequent than the evidence so far suggests, in which case their contribution to the elements that make up everything from mobile phone screens to the fuel for nuclear reactors might be revised upward again.

    For the moment, however, they appear to deliver much less buck for their bangs.

    See the full article here .

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    Stem Education Coalition

    The ARC Centre of Excellence in All Sky Astrophysics in 3 Dimensions AU unifies over 200 world-leading astronomers to understand the evolution of the matter, light, and elements from the Big Bang to the present day.

    We are combining Australian innovative 3D optical and radio technology with new theoretical supercomputer simulations on a massive scale, requiring new big data techniques.

    Through our nationwide training and education programs, we are training young scientific leaders and inspiring high-school students into STEM sciences to prepare Australia for the next generation of telescopes: the Square Kilometre Array and the Extremely Large Optical telescopes.

    The objectives for the ARC Centres of Excellence are to to:

    undertake highly innovative and potentially transformational research that aims to achieve international standing in the fields of research envisaged and leads to a significant advancement of capabilities and knowledge
    link existing Australian research strengths and build critical mass with new capacity for interdisciplinary, collaborative approaches to address the most challenging and significant research problems
    develope relationships and build new networks with major national and international centres and research programs to help strengthen research, achieve global competitiveness and gain recognition for Australian research
    build Australia’s human capacity in a range of research areas by attracting and retaining, from within Australia and abroad, researchers of high international standing as well as the most promising research students
    provide high-quality postgraduate and postdoctoral training environments for the next generation of researchers
    offer Australian researchers opportunities to work on large-scale problems over long periods of time
    establish Centres that have an impact on the wider community through interaction with higher education institutes, governments, industry and the private and non-profit sector.

     
  • richardmitnick 10:35 am on September 15, 2020 Permalink | Reply
    Tags: "Meteorite strikes may create unexpected form of silica", , , , Chemistry, ,   

    From Carnegie Institution for Science: “Meteorite strikes may create unexpected form of silica” 

    Carnegie Institution for Science
    From Carnegie Institution for Science

    August 26, 2020

    1
    A photograph of a meteorite strike site in Coconino County, Arizona. New work from Carnegie’s Sally June Tracy and collaborators Stefan Turneaure of Washington State University and Thomas Duffy of Princeton University reveals an unexpected new form of silica created in the type of extreme conditions caused by an impact. Image is courtesy of Shutterstock.

    2
    X-ray diffraction images showing the new form of silica created by sending an intense shock wave through a sample of quartz using a specialized gas gun. When the x-rays bounce off repeating planes of a crystalline structure, they scatter. This creates a distinctive ring pattern. Each ring is associated with a different plane and together this data can tell researchers about the material’s atomic-level architecture. Image is courtesy of Sally June Tracy, Stefan Turneaure, and Thomas Duffy.

    When a meteorite hurtles through the atmosphere and crashes to Earth, how does its violent impact alter the minerals found at the landing site? What can the short-lived chemical phases created by these extreme impacts teach scientists about the minerals existing at the high-temperature and pressure conditions found deep inside the planet?

    New work led by Carnegie’s Sally June Tracy examined the crystal structure of the silica mineral quartz under shock compression and is challenging longstanding assumptions about how this ubiquitous material behaves under such intense conditions. The results are published in Science Advances.

    “Quartz is one of the most abundant minerals in Earth’s crust, found in a multitude of different rock types,” Tracy explained. “In the lab, we can mimic a meteorite impact and see what happens.”

    Tracy and her colleagues—Washington State University’s (WSU) Stefan Turneaure and Princeton University’s Thomas Duffy, a former Carnegie Fellow—used specialized impact facilities to accelerate projectiles into quartz samples at extremely high speeds—several times faster than a bullet fired from a rifle. Special x-ray instruments were used to discern the crystal structure of the material that forms less than one-millionth of a second after impact. Experiments were carried out at the Dynamic Compression Sector (DCS), which is operated by WSU and located at the Advanced Photon Source, Argonne National Laboratory.

    Quartz is made up of one silicon atom and two oxygen atoms arranged in a tetrahedral lattice structure. Because these elements are also common in the silicate-rich mantle of the Earth, discovering the changes quartz undergoes at high-pressure and -temperature conditions, like those found in the Earth’s interior, could also reveal details about the planet’s geologic history.

    When a material is subjected to extreme pressures and temperatures, its internal atomic structure can be re-shaped, causing its properties to shift. For example, both graphite and diamond are made from carbon. But graphite, which forms at low pressure, is soft and opaque, and diamond, which forms at high pressure, is super-hard and transparent. The different arrangements of carbon atoms determine their structures and their properties, and that in turn affects how we engage with and use them.

    Despite decades of research, there has been a long-standing debate in the scientific community about what form silica would take during an impact event, or under dynamic compression conditions such as those deployed by Tracy and her collaborators. Under shock loading, silica is often assumed to transform to a dense crystalline form known as stishovite—a structure believed to exist in the deep Earth. Others have argued that because of the fast timescale of the shock the material will instead adopt a dense, glassy structure.

    Tracy and her team were able to demonstrate that counter to expectations, when subjected to a dynamic shock of greater than 300,000 times normal atmospheric pressure, quartz undergoes a transition to a novel disordered crystalline phase, whose structure is intermediate between fully crystalline stishovite and a fully disordered glass. However, the new structure cannot last once the burst of intense pressure has subsided.

    “Dynamic compression experiments allowed us to put this longstanding debate to bed,” Tracy concluded. “What’s more, impact events are an important part of understanding planetary formation and evolution and continued investigations can reveal new information about these processes.”

    This work is based on experiments performed at the Dynamic Compression Sector, operated by WSU under a DOE/ NNSA award. This research used the resources of the Advanced Photon Source, a Department of Energy Office of Science User Facility operated for the DOE Office of Science by the Argonne National Laboratory.


    ANL Advanced Photon Source.

    See the full article here .


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    Carnegie Institution of Washington Bldg

    Carnegie Institution for Science

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile. over 2,500 m (8,200 ft) high.


    Carnegie Las Campanas 2.5 meter Irénée Dupont telescope, Atacama Desert, over 2,500 m (8,200 ft) high approximately 100 kilometres (62 mi) northeast of the city of La Serena,Chile.

    Carnegie Institution 1-meter Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena, near the north end of a 7 km (4.3 mi) long mountain ridge, Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile.

     
  • richardmitnick 10:24 am on September 4, 2020 Permalink | Reply
    Tags: "Microwaving new materials", , , , Chemistry, Jayan used x-ray pair distribution function (PDF) analysis., Microwaving tailor-made ceramic materials with new electronic thermal and mechanical properties., Reeja Jayan,   

    From Carnegie Mellon University and Brookhaven National Lab: Women in STEM- Reeja Jayan “Microwaving new materials” 


    From Carnegie Mellon University

    and

    From Brookhaven National Lab

    9.4.20
    Sherry Stokes

    1
    Reeja Jayan

    Reeja Jayan has made a breakthrough in our understanding of how microwaves affect materials chemistry, laying the groundwork for tailor-made ceramic materials with new electronic, thermal, and mechanical properties.

    Microwave ovens are the mainstay of cooking appliances in our homes. Five years ago, when Reeja Jayan was a new professor at Carnegie Mellon University, she was intrigued by the idea of using microwaves to grow materials. She and other researchers had shown that microwave radiation enabled temperature crystallization and growth of ceramic oxides. Exactly how microwaves did this was not well understood, and this mystery inspired Jayan to reengineer a $30 microwave oven so she could investigate the dynamics effects of microwave radiation on the growth of materials.

    2
    If you look carefully in the center of this photo, you will see the $30 microwave oven that Reeja Jayan reengineered to start her experiments.
    Source credit: Reeja Jayan.

    Today, Jayan, who is now an associate professor of mechanical engineering, has made a breakthrough in our understanding of how microwaves affect materials chemistry. She and her student Nathan Nakamura exposed tin oxide (a ceramic) to 2.45 GHz microwave radiation and figured out how to monitor (in situ) atomic structural changes as they occurred. This discovery is important because she demonstrated that microwaves affected the tin oxide’s oxygen sublattice via distortions introduced in the local atomic structure. Such distortions do not occur during conventional materials synthesis (where energy is directly applied as heat).

    Unlike prior studies, which suffered from the inability to monitor structural changes while the microwaves were applied, Jayan developed novel tools (a custom-designed microwave reactor enabling in-situ synchrotron x-ray scattering) for studying these dynamic, field-driven changes in local atomic structure as they happen. By revealing the dynamics of how microwaves affect specific chemical bonds during the synthesis, Jayan is laying the groundwork for tailor-made ceramic materials with new electronic, thermal, and mechanical properties.

    3
    In-situ PDF Data Collection: Waveguide installed at 28-ID-2 beamline at the National Synchrotron Light Source II, Brookhaven National Laboratory. The results in Jayan’s paper [below] came from the custom-built microwave reactor, which offers precise engineering controls. (Source: Reeja Jayan.)

    “Once we know the dynamics, we can use this knowledge to make materials that are far away from equilibrium, as well as devise new energy efficient processes for existing materials, such as 3D printing of ceramics,” she says. The commercialization of additive manufacturing of metals and plastics is widespread, but the same cannot be said for ceramic materials. 3D printing of ceramics could advance industries ranging from healthcare—imagine artificial bones and dental implants—to industrial tooling and electronics—ceramics can survive high temperatures that metals can’t. However, integrating ceramic materials with today’s 3D printing technologies is difficult because ceramics are brittle, ultrahigh temperatures are required, and we don’t understand how to control their properties during printing processes.

    Jayan’s findings were derived from unconventional experiments that relied on a combination of tools. She used x-ray pair distribution function (PDF) analysis to provide real-time, in situ structural information about tin oxide as it was being exposed to microwave radiation. She compared these results to tin oxide that was synthesized without electromagnetic field exposure. The comparisons revealed that the microwaves were influencing atomic-scale structure by disturbing the oxygen sublattice. “We were the first to prove that microwaves create such localized interactions by devising a method to watch them live during a chemical reaction,” says Jayan.

    4
    The custom-built microwave reactor was integrated into the X-ray Powder Diffraction (XPD) beamline located at the US Department of Energy Brookhaven National Laboratory. Source: US Department of Energy Brookhaven National Laboratory.

    These experiments were extremely difficult to conduct and required a custom-built microwave reactor. (This represented a significant upgrade in cost and engineering compared to the original domestic oven). The reactor was designed in collaboration with Gerling Applied Engineering, and the experiments were conducted at the US Department of Energy Brookhaven National Laboratory (BNL). Dr. Sanjit Ghose and Dr. Jianming Bai, lead scientists at BNL, were instrumental in helping Jayan’s team integrate the microwave reactor into the beamline.

    “Another takeaway from this research is that microwaves can do more than just heating. They can have a non-thermal effect, which can rearrange the structure of materials like a jigsaw puzzle,” says Jayan. Building on this concept, she is investigating how to use microwaves to engineer new materials.

    The results of Jayan’s research were published in the Journal of Materials Chemistry A. The paper was recognized as part of the 2020 Emerging Investigators Issue of the journal. Jayan’s work was supported by a Young Investigator grant from the U.S. Department of Defense, Air Force Office of Scientific Research.

    See the full article here .

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    BNL Campus

    Brookhaven campus

    BNL Center for Functional Nanomaterials

    BNL NSLS-II


    BNL NSLS II

    BNL RHIC Campus

    BNL/RHIC Star Detector

    BNL Phenix Detector

    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.

    Carnegie Mellon University (CMU) is a global research university with more than 12,000 students, 95,000 alumni, and 5,000 faculty and staff.
    CMU has been a birthplace of innovation since its founding in 1900.
    Today, we are a global leader bringing groundbreaking ideas to market and creating successful startup businesses.
    Our award-winning faculty members are renowned for working closely with students to solve major scientific, technological and societal challenges. We put a strong emphasis on creating things—from art to robots. Our students are recruited by some of the world’s most innovative companies.
    We have campuses in Pittsburgh, Qatar and Silicon Valley, and degree-granting programs around the world, including Africa, Asia, Australia, Europe and Latin America.

     
  • richardmitnick 9:03 am on September 4, 2020 Permalink | Reply
    Tags: "A step towards a better understanding of molecular dynamics", , Attosecond scale-1×10^18 of a second (one quintillionth of a second), , Chemistry, , Femtosecond 1x10^15 or 1⁄1 000 000 000 000 000 of a second; that is one quadrillionth- or one millionth of one billionth- of a second., , Polyatomic molecules – molecules made up of several atoms.,   

    From École Polytechnique Fédérale de Lausanne: “A step towards a better understanding of molecular dynamics” 


    From École Polytechnique Fédérale de Lausanne

    04.09.20 [9.4.20]
    Sarah Perrin

    1
    EPFL researchers, working at the boundary between classical and quantum physics, have developed a method for quickly spotting molecules with particularly interesting electron properties.

    Laser technology is giving scientists an ever-closer look into molecular structures, and this sometimes leads to very interesting surprises. At EPFL’s Laboratory of Theoretical Physical Chemistry (LCPT), a research team studying the dynamics of polyatomic molecules – molecules made up of several atoms – came across one such surprise. They found that electrons in these molecules move quite differently from what would be expected in isolated atoms.

    In isolated atoms, the oscillations of electron density are regular, but in most polyatomic molecules, the oscillations quickly become damped. This process is known as decoherence. However, in some molecules the oscillations last longer before decoherence sets in. The EPFL researchers developed a method which captures the physical mechanism behind decoherence, which consequently enables them to identify molecules with long-lasting coherences. Their method could prove interesting in the development of new electron-based technology or studying quantum effects in biomolecules. The findings were recently published in Physical Review Letters.

    “Electron movement takes place extremely rapidly – on an attosecond scale [1×10^18 of a second (one quintillionth of a second)] – so it’s very difficult to observe,” says Nikolay Golubev, a post-doc at LCPT and the study’s lead author. Furthermore, electron motion is strongly coupled to other processes in a molecule. This is why the research team incorporated additional piece of information into their study: the slower dynamics of the atomic nuclei and its influence on that of electrons. It was found that in most molecular structures the slow nuclear rearrangement damps the initially coherent oscillations of electrons and makes them disappear in a few femtoseconds [10^15 or ​1⁄1 000 000 000 000 000 of a second; that is, one quadrillionth, or one millionth of one billionth, of a second].

    A semiclassical approach

    To determine whether this phenomenon is actually taking place, the researchers developed a theoretical technique for an accurate and efficient description of the dynamics of electrons and nuclei after the molecules are ionized by ultrashort laser pulses. They used what’s considered a semiclassical approach in that it combines quantum features, like the simultaneous existence of several states, and classical features, namely classical trajectories guiding the molecular wavefunctions. This method allows scientists to detect the decoherence process much faster, making it easier to analyze many molecules and therefore spot ones that could potentially have long-lasting coherences.

    “Solving the Schrödinger equation for the quantum evolution of a polyatomic molecule’s wavefunction exactly is impossible, even with the world’s largest supercomputers,” says Jiri Vanicek, head of the LCPT. “The semiclassical approach makes it possible to replace the untreatable quantum problem with a still difficult, but solvable, problem, and provides a simple interpretation in which the molecule can be viewed as a ball rolling on a high-dimensional landscape.”

    To illustrate their method, the researchers applied it to two compounds: propiolic acid, whose molecules present long lasting coherence, and propiolamide (a propiolic acid derivative), in which the decoherence is fast. The team hopes to soon be able to test their method on hundreds of other compounds as well.

    Their discovery marks an important step towards a deeper understanding of molecular structures and dynamics, and stands to be a useful tool for observing long-lived electronic coherence in molecules. Backed with a better understanding of the decoherence process, scientists could one day be able to observe exactly how molecules act in biological tissue, for example, or create new kinds of electronic circuits.

    See the full article here .

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    Please help promote STEM in your local schools.

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    EPFL bloc

    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

     
  • richardmitnick 8:13 am on September 4, 2020 Permalink | Reply
    Tags: "A chemist who plays with space", Alison Wendlandt, , Chemistry, Enantioselective catalysis, , Stereochemistry,   

    From MIT News: Women in STEM- “A chemist who plays with space” Alison Wendlandt 

    MIT News

    From MIT News

    September 3, 2020
    Fernanda Ferreira | School of Science

    Alison Wendlandt explores how the layout of atoms in molecules, such as sugars and drugs, can affect their nature and our bodies.

    1
    Alison Wendlandt, Green Career Development Assistant Professor of Chemistry. Credits: Photo: Justin Knight.

    2
    The image on the left shows the intensity of the blue LED light that drives the reaction of the synthesis of rare sugar isomers. The image on the right was taken with an orange filter, which removed blue light, to show the reaction setup itself. There are about 28 reaction vials screening a variety of variables. Credits: Image: Hayden Carder.

    Much of the earthy taste of rye bread is due to caraway seeds. These seeds get their flavor from carvone, a molecule made up of 10 carbon atoms, 14 hydrogen atoms, and one oxygen atom. But earthy isn’t the only taste that exact collection of atoms can create. The minty taste of spearmint is also due to carvone. Which flavor you get depends on the spatial distribution of the atoms in the molecule; if you placed both carvones side by side, you’d see them as mirror images of each other.

    The study of the spatial distribution of atoms in a molecule is called stereochemistry. Alison Wendlandt, the Green Career Development Assistant Professor of Chemistry at MIT, explains that when it comes to molecules, it’s not only the atoms that determine molecular properties, but also the very three-dimensional arrangement of the similarly connected atoms.

    This spatial distribution of atoms doesn’t just impact flavor. It can also determine the effectiveness of a drug molecule. Wendlandt’s work focuses on finding strategies for fine-tuning the stereochemistry of molecules and, in doing so, how quickly and thoroughly a drug treatment can work in patients.

    Mirror images

    When Wendlandt entered college, she wasn’t planning on majoring in chemistry; she was a math major. “But I ended up taking organic chemistry, and it just clicked as a language,” she says. Many students approach chemistry via memorization, but for Wendlandt the logic of chemistry innately made sense. “There was no memorizing, just understanding the rules,” she remembers. “And then at that point, there was nothing else I could do.”

    Wendlandt’s training is in catalysis, which involves designing a catalyst to get a desired reaction. “A catalyst is any kind of reagent that can promote a reaction but isn’t consumed in that reaction,” says Wendlandt. This can be a reaction that is hard to perform, or one that leads to a specific product or outcome. During her postdoc at Harvard University, she focused on enantioselective catalysis, where a specific enantiomer, one of a pair of mirror image molecules, is generated.

    There are a number of aspects of enantioselective catalysis that attract Wendlandt to the work, but two stand out. “One is the importance of chiral drug molecules,” she says. With drug molecules, it’s often the case that only one enantiomer has the drug properties of interest, while the other has no effect or, in some cases, a negative effect. “There are some famous catastrophes where our failure to control or acknowledge the off-target effects of enantiomers led to disasters.” Thalidomide, which was taken by pregnant women in the 1950s, is one such example. “One enantiomer was fine and treated morning sickness effectively, and the other enantiomer was a teratogen and led to birth defect issues,” says Wendlandt. “It was totally a stereochemistry problem.”

    Wendlandt is also attracted to the molecular design aspect of the work. “It allows us to make a very small energetic change to reaction coordinates,” she says. In terms of energy, Wendlandt explains, 1,000-2,000 calories — like the ones you consume and use for energy — can determine whether a product is a balanced mix of two enantiomers or whether it’s a pure mix of just the one enantiomer of interest. With catalysis, Wendlandt says, you can actually control the reaction’s path.

    Sugar rush

    Many molecules have stereochemistry, but the class of molecules Wendlandt is particularly interested in are sugars. She explains that, for molecules like amino acids and proteins, their properties are often determined by their functional groups, groupings of atoms on the molecule that give it a specific nature. This is not the case with sugars. “Many of the biological and physical properties of sugars are stereochemistry-related,” Wendlandt says. With some important exceptions, all sugars are isomers, meaning they share the same basic chemical formula. “They just differ in terms of their spatial connectivity.”

    In the body, sugars serve a number of functions, from energy and information storage to structure, and they’re also common components in pharmaceutical drugs. Some sugars, such as glucose and cellulose, are easy to come by, but others, particularly those that can be active ingredients in drugs, are harder to produce. These rare sugars “have to be made by chemical synthesis,” says Wendlandt.

    Despite the importance of sugars, studying them is hampered by subpar methods for producing rare sugars, says Wendlandt. “And the reason these methods are poor has to do with our inability to manage issues of selectivity,” she says. Because the property of sugars are determined by their stereochemistry, making a rare sugar often comes down to moving a specific atom from one location on the molecule to another. It’s a major challenge, but one Wendlandt is drawn to.

    In a January 2020 paper in Nature, Wendlandt and her lab made allose, a rare sugar, by modifying the spatial distribution of atoms in a glucose molecule. The process involved breaking a chemical bond in one spot and reforming it in another spot on the molecule, which goes against a chemical principle called microscopic reversibility. “It dictates that the way the bond is broken is the same way that the bond is formed,” explains Wendlandt. To get around this, the lab decoupled the bond-breaking and bond-forming process by using two catalysts: one to break the bond and another to form it. With these two separate catalysts and some blue light to drive catalysis, a hydrogen atom is removed from a specific spot on the sugar molecule while a new hydrogen atom is added to another stereochemical position on that same molecule. With this switch, common glucose became rare allose.

    Making allose is just the start. What drives the site selectivity of the reaction is not yet clear, and it’s a question Wendlandt and her lab are continuing to probe. “If we can understand why these reactions are selective, we can, in principle, design them to do other things,” says Wendlandt, such as breaking bonds at other sites on the molecule. Once predictability and stability is honed, this method can become a powerful tool in pharmaceuticals, including many FDA-approved antiviral, antibacterial, anti-cancer, and cardiac drugs. “A medicinal chemist can come in and say ‘OK, I want to edit this bond or that bond,’” imagines Wendlandt, letting them fine-tune sugars into potent pharmaceutical ingredients. This tinkering of atoms in a molecule can mean the difference between tragedy and safe, effective drugs.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition


    USPS “Forever” postage stamps celebrating Innovation at MIT

    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

     
  • richardmitnick 11:26 am on August 25, 2020 Permalink | Reply
    Tags: "Tracing the Cosmic Origin of Complex Organic Molecules with Their Radiofrequency Footprint", 45 m radio telescope of the Nobeyama Radio Observatory., A special organic molecule called acetonitrile (CH3CN)., , , , , , Chemistry, COMs in the low-density regions of molecular clouds emit less radio waves making it difficult for us to detect them., COMs-complex organic molecules, , Instead of going for radio wave emissions they focused on radio wave absorption., Many scientists have reported finding all sorts of COMs in molecular clouds-gigantic regions of interstellar space that contain various types of gases., , , Scientists confirm the presence of acetonitrile in a distant interstellar gas cloud using a radio telescope.,   

    From Tokyo University of Science: “Tracing the Cosmic Origin of Complex Organic Molecules with Their Radiofrequency Footprint” 

    From Tokyo University of Science

    2020.08.25

    Scientists confirm the presence of acetonitrile in a distant interstellar gas cloud using a radio telescope.

    1

    How did organic matter reach the Earth in the first place? One way to ponder this question is by observing the distribution and abundance of complex organic molecules in interstellar gas clouds. However, detecting such molecules in the less dense regions of these gas clouds has been challenging. Now, scientists from Japan have found concluding evidence for the presence of a particular complex organic molecule in such a region for the first time.

    2
    The 45-meter radio telescope at the Nobeyama Radio Observatory in Japan.
    Photo courtesy: Dr Mitsunori Araki from Tokyo University of Science.

    The origin of life on Earth is a topic that has piqued human curiosity since probably before recorded history began. But how did the organic matter that constitutes lifeforms even arrive at our planet? Though this is still a subject of debate among scholars and practitioners in related fields, one approach to answering this question involves finding and studying complex organic molecules (COMs) in outer space.

    Many scientists have reported finding all sorts of COMs in molecular clouds-gigantic regions of interstellar space that contain various types of gases. This is generally done using radio telescopes, which measure and record radio frequency waves to provide a frequency profile of the incoming radiation called spectrum. Molecules in space are usually rotating in various directions, and they emit or absorb radio waves at very specific frequencies when their rotational speed changes. Current physics and chemistry models allow us to approximate the composition of what a radio telescope is pointed at, via analysis of the intensity of the incoming radiation at these frequencies.

    In a recent study published in Monthly Notices of the Royal Astronomical Society, Dr Mitsunori Araki from Tokyo University of Science, along with other scientists from across Japan, tackled a difficult question in the search for interstellar COMs: how can we assert the presence of COMs in the less dense regions of molecular clouds? Because molecules in space are mostly energized by collisions with hydrogen molecules, COMs in the low-density regions of molecular clouds emit less radio waves, making it difficult for us to detect them. However, Dr Araki and his team took a different approach based on a special organic molecule called acetonitrile (CH3CN).

    Acetonitrile is an elongated molecule that has two independent ways of rotating: around its long axis, like a spinning top, or as if it were a pencil spinning around your thumb. The latter type of rotation tends to spontaneously slow down due to the emission of radio waves and, in the low-density regions of molecular clouds, it naturally becomes less energetic or “cold.”

    In contrast, the other type of rotation does not emit radiation and therefore remains active without slowing down. This particular behavior of the acetonitrile molecule was the basis on which Dr Araki and his team managed to detect it. He explains:

    “In low-density regions of molecular clouds, the proportion of acetonitrile molecules rotating like a spinning top should be higher. Thus, it can be inferred that an extreme state in which a lot of them would be rotating in this way should exist. Our research team was, however, the first to predict its existence, select astronomical bodies that could be observed, and actually begin exploration.”

    Instead of going for radio wave emissions, they focused on radio wave absorption. The “cold” state of the low-density region, if populated by acetonitrile molecules, should have a predictable effect on the radiation that originates in celestial bodies like stars and goes through it. In other words, the spectrum of a radiating body that we perceive on Earth as being “behind” a low-density region would be filtered by acetonitrile molecules spinning like a top in a calculable way, before it reaches our telescope on earth. Therefore, Dr Araki and his team had to carefully select radiating bodies that could be used as an appropriate “background light” to see if the shadow of “cold” acetonitrile appeared in the measured spectrum. To this end, they used the 45 m radio telescope of the Nobeyama Radio Observatory, Japan, to explore this effect in a low-density region around the “Sagittarius molecular cloud Sgr B2(M),” one of the largest molecular clouds in the vicinity of the center of our galaxy.

    3
    Using radio wave absorption to detect acetonitrile in the molecular cloud of Sgr B2(M) at the center of our galaxy. Courtesy: Dr Mitsunori Araki from Tokyo University of Science.

    4
    The observation setup. Source: National Astronomical Observatory of Japan [NAOJ]. Photo courtesy: Mr Daitoshi Ishihara.

    After careful analysis of the spectra measured, the scientists concluded that the region analyzed was rich in acetonitrile molecules rotating like a spinning top; the proportion of molecules rotating this way was actually the highest ever recorded. Excited about the results, Dr Araki remarks:

    “By considering the special behavior of acetonitrile, its amount in the low-density region around Sgr B2(M) can be accurately determined. Because acetonitrile is a representative COM in space, knowing its amount and distribution though space can help us probe further into the overall distribution of organic matter.”

    Ultimately, this study may not only give us some clues about where the molecules that conform us came from, but also serve as data for the time when humans manage to venture outside the solar system.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Tokyo University of Science was founded in 1881 as The Tokyo Academy of Physics by 21 graduates of the Department of Physics in the Faculty of Science, University of Tokyo (then the Imperial University). In 1883, it was renamed the Tokyo College of Science, and in 1949, it attained university status and became the Tokyo University of Science. The leading character appearing in Japanese novelist Soseki Natsume’s novel Botchan graduated from Tokyo University of Science.

    As of 2016, it is the only private university in Japan that has produced a Nobel Prize winner and the only private university in Asia to produce Nobel Prize winners within the natural sciences field.

     
  • richardmitnick 5:31 pm on August 20, 2020 Permalink | Reply
    Tags: "A new X-ray detector snaps 1000 atomic-level pictures per second of nature's ultrafast processes", , , , Chemistry, , , , , The ePix10k detector, The new device can handle extremely bright X-ray beams as well as single photons., Time-resolved serial crystallography at Argonne's APS X-ray light source is an important application.,   

    From SLAC National Accelerator Lab: “A new X-ray detector snaps 1,000 atomic-level pictures per second of nature’s ultrafast processes” 

    From SLAC National Accelerator Lab

    August 20, 2020
    Manuel Gnida

    The ePix10k detector is ready to advance science at SLAC’s Linac Coherent Light Source X-ray laser [below] and at facilities around the world.

    Scientists around the world use synchrotrons and X-ray lasers to study some of nature’s fastest processes. These machines generate very bright and short X-ray flashes that, like giant strobe lights, “freeze” rapid motions and allow researchers to take sharp snapshots and make movies of atoms buzzing around in a sample.

    A new generation of X-ray detectors developed at the Department of Energy’s SLAC National Accelerator Laboratory, called ePix10k, can take up to 1,000 of these snapshots per second – almost 10 times more than previous generations – to make more efficient use of light sources that fire thousands of X-ray flashes per second. Compared to previous ePix and other detectors, this X-ray “camera” can also handle more X-ray intensity, is three times more sensitive, and is available with higher resolution – up to 2 megapixels.

    1
    Four units of the ePix10k camera, ready to further X-ray science at SLAC’s Linac Coherent Light Source (LCLS) and facilities worldide. The camera can capture up to 1,000 X-ray images per second, almost 10 times more than previous detector generations. (Christopher Kenney/SLAC National Accelerator Laboratory.)

    The ePix10k will become the new workhorse for X-ray science at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser, and it’s also benefitting other facilities. Teams at the Advanced Photon Source (APS) at DOE’s Argonne National Laboratory and at European XFEL in Germany are already using the technology, and more groups could follow suit in the near future.

    “With the ePix10k, we pushed the state of the art and created a new camera with truly unique features,” says SLAC senior scientist Christopher Kenney, who led the camera construction project. “It’s a great development that is now available to facilities around the world.”

    Pushing the limits

    SLAC’s ePix X-ray cameras are designed to match the specific needs of scientists who use powerful X-ray light sources to study the atomic details of chemistry, biology and materials. They are fast, perform stably over long periods of time and are sensitive to a broad range of X-ray intensities, meaning they can handle extremely bright X-ray beams as well as single photons.

    The cameras consist of two major core parts: a light-sensitive sensor and an application-specific integrated circuit, or ASIC, that processes the signals picked up by the sensor and gives the camera its unique properties.

    Previous detectors, such as ePix100 used by LCLS scientists for several years, were tailored to maximize performance at the X-ray laser’s firing rate of 120 pulses per second. SLAC’s detector team further developed the technology so that it can now be used to capture up to 1,000 images per second.

    “When we started the project, we already knew that our ASICs could handle higher rates, but it wasn’t clear how far we could push the rest of the technology,” says SLAC electrical engineer Maciej Kwiatkowski.

    It turns out the path to a detector that can take images at a 10 times higher rate was relatively straightforward: Without the need to change any of the camera’s hardware, the team reached the new specifications by upgrading and tuning only the device’s firmware, which is similar to a program that is embedded in the camera and defines its functionality.

    “The real challenge was to adjust the camera’s parameters to operate at the new speed limit without degrading camera performance,” says SLAC physicist Gabriel Blaj, who was in charge of testing the new device. “But in the end, we were able to use the technology we’ve been developing for several years and run it faster.”

    Applications around the world

    To get the camera ready for its use at LCLS, the team tested it first with an X-ray tube at SLAC. Last year, they also took a prototype to the BioCARS beamline at APS, an experimental station for studies of processes in biology and chemistry.

    One of the techniques used at the beamline is time-resolved serial crystallography, in which researchers shoot laser light at a jet of tiny crystals and use APS X-rays to examine how the crystals’ atomic structure responds to the laser stimulus.

    “We apply this method to proteins to learn, for instance, how enzymes catalyze important biological reactions,” says BioCARS operations manager Robert Henning from the University of Chicago. “In principle, we could do these experiments with up to 1,000 X-ray pulses per second at APS, but most detectors can’t handle the full intensity associated with that rate.”


    The new ePix X-ray camera, capable of taking up to 1,000 images per second, has been tested at the BioCARS experimental station at Argonne National Laboratory’s Advanced Photon Source. This video, recorded with the camera during the tests, shows a changing pattern of X-rays scattered by crystals. (Robert Henning/University of Chicago, Gabriel Blaj/SLAC National Accelerator Laboratory)

    The new detector will let scientists use the X-ray source’s full firing power, saving them a lot of time.

    “To obtain a complete data set, we typically need to take thousands of X-ray shots,” Henning says. “Being able to use every single one of APS’s pulses will cut down the time it takes to accomplish that.”

    The new ePix detector is also already in use at the European XFEL, a powerful new X-ray laser in Germany that will eventually fire up to 27,000 times per second. SLAC has partnered with Rayonix, a company that develops X-ray detectors for research, to commercialize the technology under a DOE Small Business Innovation Research grant.

    Scalable in size

    One important feature of the ePix detector is that individual units can be tiled together into a larger detector, which improves the resolution of the X-ray images it takes. Last year’s tests at APS were done with a single unit containing 130,000 pixels. Henning’s team has now ordered a model that will combine 16 of these units into a 2.2-megapixel detector about a foot across.

    A new 16-unit version has also been installed at LCLS, which just came back online after a major upgrade of its undulator magnets. The upgrade, together with the new detector, will allow scientists to study the motions of atoms with higher resolution than before.

    3
    A 16-module, 2.2-megapixel ePix10k X-ray camera has been installed at SLAC’s Linac Coherent Light Source (LCLS) X-ray laser. (Tim van Driel/SLAC National Accelerator Laboratory)

    “The detector will become the new workhorse for our science,” says LCLS instrument scientist Tim van Driel. “It can handle 100 times more X-ray intensity and is much larger than the previous version, ePix100. It’ll also replace other large-area detectors that we’ve been using for the past 10 years.”

    Van Driel studies how molecules scatter and absorb X-rays in solution to learn more about chemical processes, such as bond breaking and formation, on an atomic level. But extracting this information is challenging.

    “The signals we’re looking for are subtle changes in X-ray intensity – a thousand times smaller than the background intensity,” he says. “So, we need a very flexible detector that can adjust its sensitivity so that it can handle tens of thousands of photons per second of background signals while detecting very few, even single photons associated with tiny chemical changes. The new device is designed to switch automatically between different sensitivities, so it’s just the right detector for the job.”

    Future challenges

    Delivering the ePix10k technology with a frame rate of 1,000 images per second is a major milestone, but the next challenge already awaits SLAC’s X-ray detector developers.

    The next-generation X-ray laser LCLS-II [depicted below], currently under construction at SLAC, will produce up to a million pulses per second, and no X-ray detector in the world today is able to keep up with that speed.

    “Our detector team has a plan,” says SLAC senior engineer Angelo Dragone, who is in charge of detector R&D strategic planning at the lab. “A new generation of detectors, ePixHR, will be able to take 5,000 and 25,000 images per second. It’s already in the prototyping phase, and our ultimate goal is to further push that technology to 100,000 images per second.”

    In addition, the team is working on a revolutionary new class of cameras, called SparkPix, which will be able to collect images at the same high rate at which LCLS-II will fire X-ray pulses and to process data in real time.

    This work was supported by the DOE Office of Science. LCLS and APS are Office of Science user facilities.

    See the full article here .


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    Please help promote STEM in your local schools.

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    SLAC National Accelerator Lab


    SLAC/LCLS


    SLAC/LCLS II projected view


    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.

    SSRL and LCLS are DOE Office of Science user facilities.

     
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