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  • richardmitnick 5:45 pm on September 23, 2020 Permalink | Reply
    Tags: "UCLA scientists create world’s smallest ‘refrigerator’", An additional distinguishing feature of the team’s nanoscale “refrigerator” is that it can respond almost instantly., , At larger scales the same technology is used to cool computers and other electronic devices., Indium nanoparticles which the team used as thermometers., Nanotechnology, , The scientific instruments on NASA’s Voyager spacecraft have been powered for 40 years by electricity from thermoelectric devices wrapped around heat-producing plutonium., Thermoelectric coolers that are only 100 nanometers thick., UC Los Angeles, When heat is applied one side becomes hot and the other remains cool; that temperature difference can be used to generate electricity.   

    From UC Los Angeles: “UCLA scientists create world’s smallest ‘refrigerator’” 

    UCLA bloc

    From UC Los Angeles

    September 22, 2020

    Lisa Garibay
    310-825-1040
    lgaribay@ucla.edu

    1
    Dewdrop forms on thermoelectric cooler. A team led by UCLA physics professor Chris Regan has succeeded in creating thermoelectric coolers that are only 100 nanometers thick — roughly one ten-millionth of a meter — and have developed an innovative new technique for measuring their cooling performance. Credit: UCLA/Regan Group.

    2
    This electron microscope image shows the cooler’s two semiconductors — one flake of bismuth telluride and one of antimony-bismuth telluride — overlapping at the dark area in the middle, which is where most of the cooling occurs. The small “dots” are indium nanoparticles, which the team used as thermometers. UCLA/Regan Group

    How do you keep the world’s tiniest soda cold? UCLA scientists may have the answer.

    A team led by UCLA physics professor Chris Regan has succeeded in creating thermoelectric coolers that are only 100 nanometers thick — roughly one ten-millionth of a meter — and have developed an innovative new technique for measuring their cooling performance.

    “We have made the world’s smallest refrigerator,” said Regan, the lead author of a paper on the research published recently in the journal ACS Nano.

    To be clear, these miniscule devices aren’t refrigerators in the everyday sense — there are no doors or crisper drawers. But at larger scales, the same technology is used to cool computers and other electronic devices, to regulate temperature in fiber-optic networks, and to reduce image “noise” in high-end telescopes and digital cameras.

    What are thermoelectric devices and how do they work?

    Made by sandwiching two different semiconductors between metalized plates, these devices work in two ways. When heat is applied, one side becomes hot and the other remains cool; that temperature difference can be used to generate electricity. The scientific instruments on NASA’s Voyager spacecraft, for instance, have been powered for 40 years by electricity from thermoelectric devices wrapped around heat-producing plutonium. In the future, similar devices might be used to help capture heat from your car’s exhaust to power its air conditioner.

    3
    A standard thermoelectric device, which is made of two semiconductor materials sandwiched between metalized plates. Wikimedia Commons.

    But that process can also be run in reverse. When an electrical current is applied to the device, one side becomes hot and the other cold, enabling it to serve as a cooler or refrigerator. This technology scaled up might one day replace the vapor-compression system in your fridge and keep your real-life soda frosty.

    What the UCLA team did

    To create their thermoelectric coolers, Regan’s team, which included six UCLA undergraduates, used two standard semiconductor materials: bismuth telluride and antimony-bismuth telluride. They attached regular Scotch tape to hunks of the conventional bulk materials, peeled it off and then harvested thin, single-cystal flakes from the material still stuck to the tape. From these flakes, they made functional devices that are only 100 nanometers thick and have a total active volume of about 1 cubic micrometer, invisible to the naked eye.

    To put this tiny volume in perspective: Your fingernails grow by thousands of cubic micrometers every second. If your cuticles were manufacturing these tiny coolers instead of fingernails, each finger would be churning out more than 5,000 devices per second.

    “We beat the record for the world’s smallest thermoelectric cooler by a factor of more than ten thousand,” said Xin Yi Ling, one of the paper’s authors and a former undergraduate student in Regan’s research group.

    While thermoelectric devices have been used in niche applications due to advantages such as their small size, their lack of moving parts and their reliability, their low efficiency compared with conventional compression-based systems has prevented widespread adoption of the technology. Simply put, at larger scales, thermoelectric devices don’t generate enough electricity, or stay cold enough — yet.

    But by focusing on nanostructures — devices with at least one dimension in the range of 1 to 100 nanometers — Regan and his team hope to discover new ways of synthesizing better-performing bulk materials. The sought-after properties for materials in high-performance thermoelectric coolers are good electrical conductivity and poor thermal conductivity, but these properties are almost always mutually exclusive. However, a winning combination might be found in nearly two-dimensional structures like those Regan’s team has created.

    An additional distinguishing feature of the team’s nanoscale “refrigerator” is that it can respond almost instantly.

    “Its small size makes it millions of times faster than a fridge that has a volume of a millimeter cubed, and that would be already be millions of times faster than the fridge you have in your kitchen,” Regan said.

    “Once we understand how thermoelectric coolers work at the atomic and near-atomic level,” he said, “we can scale up to the macroscale, where the big payoff is.”

    Measuring how cold the devices become

    Measuring temperature in such tiny devices is a challenge. Optical thermometers have poor resolution at such small scales, while scanning probe techniques require specialized, expensive equipment. Both approaches require painstaking calibrations.

    In 2015, Regan’s research group developed a thermometry technique called PEET, or plasmon energy expansion thermometry, which uses a transmission electron microscope to determine temperatures at the nanoscale by measuring changes in density.

    To measure the temperature of their thermoelectric coolers, the researchers deposited nanoparticles made of the element indium on each one and selected one specific particle to be their thermometer. As the team varied the amount of power applied to the coolers, the devices heated and cooled, and the indium correspondingly expanded and contracted. By measuring the indium’s density, the researchers were able to determine the precise temperature of the nanoparticle and thus the cooler.

    “PEET has the spatial resolution to map thermal gradients at the few-nanometer scale — an almost unexplored regime for nanostructured thermoelectric materials,” said Regan, who is a member of the California NanoSystems Institute at UCLA.

    To supplement the PEET measurements, the researchers invented a technique called condensation thermometry. The basic idea is simple: When normal air cools to a certain temperature — the dew point — water vapor in the air condenses into liquid droplets, either dew or rain. The team exploited this effect by powering their device while watching it with an optical microscope. When the device reached the dew point, tiny dewdrops instantly formed on its surface.

    Regan praised the work of his student researchers in helping to develop and measure the performance the nanoscale devices.

    “Connecting advanced materials science and electron microscopy to physics in everyday areas, like refrigeration and dew formation, helps students get traction on the problems very quickly,” Regan said. “Watching them learn and innovate gives me a lot of hope for the future of thermoelectrics.”

    See the full article here .

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    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 10:18 am on September 21, 2020 Permalink | Reply
    Tags: "High-sensitivity nanoscale chemical imaging with hard x-ray nano-XANES", , EELS-Electron energy-loss spectroscopy, Nanotechnology, , TEM-Transmission electron microscopy, , XAS-X-ray absorption spectrometry   

    From phys.org and Brookhaven National Laboratory: “High-sensitivity nanoscale chemical imaging with hard x-ray nano-XANES” 


    From phys.org

    and

    Brookhaven National Laboratory

    September 21, 2020
    Thamarasee Jeewandara

    1
    Acquisition of nano-XANES. (A) Schematic of the hard x-ray nanoprobe beamline of NSLS-II [below]. As the sample is raster-scanned by a nanobeam produced from a Fresnel zone plate (FZP), diffraction (not used for samples studied in this work), fluorescence, and transmitted signals can all be collected simultaneously. At energy points along the absorption edge, a series of x-ray fluorescence [nano–x-ray fluorescence (XRF)] maps (B) and phase images from ptychography reconstruction (C) are obtained. (D) Representative fluorescence-yield single-pixel XANES fitted with reference standards. Credit: Science Advances, doi: 10.1126/sciadv.abb3615.

    X-rays with excellent penetration power and high chemical sensitivity are suited to understand heterogeneous materials. In a new report on Science Advances, A. Pattammattel, and a team of scientists at the BNL NSLS-II in New York, U.S., described nanoscale chemical speciation by combining scanning nanoprobe and fluorescence-yield X-ray absorption near-edge structure—known as nano-XANES. The team showed the resolving power of nano-XANES by mapping states of iron of a reference sample composed of stainless steel and hematite nanoparticles using 50-nanometer scanning steps. Using nano-XANES, the team also studied the trace secondary phases of lithium iron phosphate (LFP) particles and noted the individual iron(Fe)-phosphide nanoparticles within the pristine lithium iron phosphate, while partially delithiated particles showed Fe-phosphide nanonetworks. This work on nano-XANES highlight the contradictory reports on iron-phosphide morphology within the existing literature and will bridge the capability gap of spectromicroscopy methods to provide exciting research opportunities.

    Multidisciplinarity of nanotechnology

    Nanotechnology is a rapidly growing field and has expanded to multidisciplinary research fields in the past two decades. The field has also unveiled microscopic characterization tools to understand the chemical and physical properties of materials with a significant role in materials science. Researchers have developed a myriad of techniques to study the spectrum of nanomaterials including transmission electron microscopy (TEM) for imaging at atomic resolution and electron energy-loss spectroscopy (EELS) to detect element-specific chemical states and data. However, EELS is limited by poor penetration depth and plural scattering, while in contrast, X-rays have a wide energy range alongside excellent penetration power and high chemical sensitivity. For example, X-ray absorption spectrometry (XAS) is widely used to investigate the chemical state of the absorbing atom. The quantitative chemical imaging achieved with a hard X-ray nanoprobe and single pixel XANES (X-ray absorption near-edge structure) at the nanoscale is still an unchartered territory. In this work, Pattammattel et al. therefore detailed the fluorescence-yield hard X-ray XANES at the nanoscale, hitherto referred to as nano-XANES.

    2
    Quality of nano-XANES and comparison with micro-XANES. A) Fe K-edge nanoXANES spectra of hematite [Fe(III)] and stainless steel [Fe(0)] particles with different integration areas. B) A comparison of nano-XANES Fe(III) and Fe(0) spectra with micro-XANES and the hematite and stainless steel reference standards (collected at the microprobe beamline) showing identical features. Credit: Science Advances, doi: 10.1126/sciadv.abb3615.

    Nano-XANES acquisition

    The scientists demonstrated the technique by performing a benchmark experiment using a reference sample containing mixed stainless steel and hematite nanoparticles. They then applied the technique to characterize the chemical species (i.e. speciation) of lithium battery particles (containing LixFePO4, abbreviated LFP), with a trace secondary Fe-phosphide/Fe-phosphocarbide phase. The high spatial resolution and detection sensitivity of nano-XANES provided unique insight into materials properties under complex environments. The team conducted the nano-XANES experiment at the Hard X-ray Nanoprobe Beamline at the NSLS-II, at the Brookhaven National Laboratory. Using the simultaneously acquired far-field diffraction patterns, Pattammattel et al. generated phase images with a higher spatial resolution through ptychography reconstruction. They then aligned the elemental maps by using an imaging software and created a three-dimensional (3-D) image stack to produce spatially resolved chemical state information. The reference sample used in the work contained stainless steel nanoparticles, hematite nanoparticles and a mixture of the two with a varying thickness from tens to a few hundred nanometers. The team chose the Fe(0)/Fe(III) reference system due to two reasons, which included the distinguishable spectral features and the accuracy of the fitting method.

    3
    Chemical imaging with nano-XANES. (A) Comparison of summed Fe K-edge nano-XANES spectra of Fe(III) and Fe(0) nanoparticles with the bulk ones. (B) and (C) are Fe-Kα XRF and ptychography phase images of hematite [Fe(III)] and stainless steel [Fe(0)] nanoparticle aggregate. (D) Representative single-pixel spectra and their fittings at different locations of the particle are marked in (E), which shows the chemical state map of Fe. (F) XRF map of chromium (alloyed with Fe), overlaid with Fe(0). It confirms the fidelity of the fitting. Scale bars, 800 nm. Data collection details: 120 × 80 points, 50-nm steps, 40-ms dwell time, 77 energy points, and ~8.2 hours total acquisition time. Credit: Science Advances, doi: 10.1126/sciadv.abb3615.

    Troubleshooting nano-XANES acquisition

    The biggest challenge of the technique was maintaining beam stability as the energy varied so that the size and position of the nanobeam did not change, while the illumination of the lens remained constant. The scientists overcame the challenges by aligning the system to predefined energy points, and by creating a look-up table to correct motor positions. The stability of the associated microscope was also critical in the long-term since many acquisitions took up to 10 hours. The team assessed the quality of nano-XANES by comparing the spectrum of each species with a bulk measurement conducted at the X-ray fluorescence microprobe beamline. Pattammattel et al. compared the results with additional techniques for spectromicroscopic imaging to conclude that the fluorescence-yield nano-XANES provided the highest sensitivity.

    Detecting trace secondary phases in lithium iron phosphate particles

    The scientists then used nano-XANES to follow single-particle phase transformations in lithium-ion battery materials. They identified olivine-structured lithium iron phosphate (LiFePO4, LFP) with high chemical contrast and spatial resolution to image chemical changes during battery performance. The LFP is a cathode material commercially used in Li-ion batteries due to its long lifecycle, cost-effectiveness, and low-environmental toxicity. Carbon-coated LFP particles can enhance electronic conductivity but also cause unexpected side reactions including the formation of nanostructured iron-rich compounds (classified in this work as Fe-phosphides).

    4
    Chemical imaging to identify Fe-rich phases in pristine (top) and partially lithiated LFP (bottom). (A and B) XRF map of Fe and P of pristine LFP particle. (C) Chemical state map produced by fitting with Fe(II) and Fe3P reference standards. (D) Phase image from ptychography reconstruction. (E) XANES spectra from selected regions displaying the spectral changes. Scale bars, 1 μm. Data collection details: 100 × 100 points, 60-nm steps, 30-ms dwell time, 53 energy points, and ~5 hours total acquisition time. (F and G) XRF map of Fe and P of the partially lithiated LFP particle. (H) Chemical state map produced by fitting with Fe(II), Fe(III), and Fe3P reference standards. (I) Phase image from ptychography reconstruction. (J to L) Deconvoluted distribution of Fe(II), Fe3P, and Fe(III). (M) XANES spectra from selected regions displaying the spectral changes with deconvoluted phases. Conductive carbon and polymer binder in the electrode are responsible for the background features seen in the phase images. Scale bars, 1.4 μm. Data collection details: 100 × 100 points, 70-nm steps, 30-ms dwell time, 65 energy points, and ~6 hours total acquisition time. Credit: Science Advances, doi: 10.1126/sciadv.abb3615.

    Nano-XANES with high spatial resolution provided a unique X-ray technique to detect chemical species of heterogenous matrices such as carbon-coated LFP (lithium iron phosphate). While spectroscopic differentiation was not possible between Fe-phosphides and carbides due to their similarity in local bonding, the team achieved chemical mapping along with Fe (II) and Fe (III) references. The pristine samples exhibited several 100 to 1000 nm particles of Fe-phosphides surrounding the LFP particle with clear grain boundaries and high resolution in agreement with electron microscopy studies. Since X-rays did not penetrate through the entire thickness of the sample, Pattammattel et al. could not determine if the Fe-phosphide network formed on the surface or inside the particle during this study. The nano-XANES technology provided a unique characterization tool with high penetration depth and detection sensitivity for future investigations.

    Applications of nano-XANES

    The hard X-ray nano-XANES technique can fluorescently bridge the capability gap of existing spectromicroscopy techniques. The team foresee broad applications of the method for nano-speciation of catalytic systems, electrode materials, environmental pollutants and bio-nanosystems. However, they must first overcome a few challenges of the method including self-absorption problems with thick and dense samples, radiation damage by the nanobeam and slow imaging speed. In this way, A. Pattammattel and colleagues expect an optimized tomographic nano-XANES technique to have broad impact on multidisciplinary nanotechnology research and the discovery of unexpected or hidden phases of materials in the future. The improved techniques will greatly enhance the detection capability of nano-XANES to identify trace chemical phases and realize higher chemical specificity as well as detect local bonding structures.

    Previous science paper:
    Nanoscale X-ray imaging
    Nature Photonics

    See the full article here .

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    Brookhaven Campus.


    BNL Center for Functional Nanomaterials.

    BNL NSLS-II.


    BNL NSLS II.


    BNL RHIC Campus.

    BNL/RHIC Star Detector.

    BNL/RHIC Phenix.

    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 3:06 pm on September 17, 2020 Permalink | Reply
    Tags: "Lighting the way to infrared detection", , , , Nanotechnology,   

    From École Polytechnique Fédérale de Lausanne: “Lighting the way to infrared detection” 


    From École Polytechnique Fédérale de Lausanne

    17.09.20
    Philippe Roelli

    1
    EPFL physicists propose a new path to detect infrared radiation with outstanding sensitivity, allowing detection of signals as low as that of a single quantum of light.

    When using our webcam or cell phone camera, we experience the tremendous capabilities of cheap and compact sensors developed in the past decades for the visible region of the electromagnetic spectrum. On the contrary, detection of lower frequency radiation not visible to the human eye (such as mid- and far-infrared radiation) requires complex and costly equipment. Lack of a compact technology impedes widespread access to sensors for the recognition of molecules and the imaging of thermal radiation naturally emitted by our bodies. A new conceptual breakthrough in this field may therefore have tremendous impacts in our daily lives.

    The most popular technique currently available to detect mid- and far-infrared radiation consists in bolometers, which are made up of arrays of small thermometers measuring the heat produced by absorption of radiation. They have many limitations, in particular being slow to respond and unable to detect weak levels of radiation.

    The novel approach proposed by the EPFL team led by Christophe Galland and Tobias Kippenberg follows a completely different route: first convert the invisible radiation into visible light, and then detect it with existing technologies. At the core of the new concept lie hybrid metal-molecule nanostructures. The metal is tailored to focus infrared radiation on the molecules, which are thereby brought into vibration. Next, the energy of the vibrating molecules is converted again into radiation, but this time at a much higher frequency, in the visible domain. The hybrid nanostructure, designed in collaboration with Diego Martin-Cano (Max-Planck Institute for Light, Erlangen, Germany), allows for high conversion efficiency while reducing the size of the device to dimensions significantly smaller than the wavelength of the infrared light.

    2
    Credit: P. Roelli (EPFL)

    Philippe Roelli, lead author on the study, highlights that, among the various conceptual advances envisioned by their scheme, the most intriguing aspect concerns its potential sensitivity: ‘The low level of noise added by the molecular vibration during the conversion process enables the detection of extremely weak signals at room temperature. With advanced devices, we anticipate to reach quantum limited conversion and have the unique opportunity to resolve the signal of single quanta of infrared light’.

    The EPFL study will inspire future works at the interface between surface science, nanotechnology and quantum optics to foster the development of novel devices with applications in infrared sensing and imaging.

    Science paper:
    Molecular Platform for Frequency Upconversion at the Single-Photon Level
    Physical Review X

    See the full article here .

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    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 12:17 pm on September 8, 2020 Permalink | Reply
    Tags: A quantum or squeezed light approach for atomic force microscopy that enables measurement of signals otherwise buried by noise., , Atomic force microscope microcantilever, , Nanotechnology, Nonlinear interferometry, ,   

    From Oak Ridge National Laboratory: “Quantum light squeezes the noise out of microscopy signals” 

    i1

    From Oak Ridge National Laboratory

    September 8, 2020

    Dawn M Levy
    levyd@ornl.gov
    865.576.6448

    Researchers at the Department of Energy’s Oak Ridge National Laboratory used quantum optics to advance state-of-the-art microscopy and illuminate a path to detecting material properties with greater sensitivity than is possible with traditional tools.

    1
    ORNL researchers developed a quantum, or squeezed, light approach for atomic force microscopy that enables measurement of signals otherwise buried by noise. Credit: Raphael Pooser/ORNL, U.S. Dept. of Energy.

    “We showed how to use squeezed light – a workhorse of quantum information science – as a practical resource for microscopy,” said Ben Lawrie of ORNL’s Materials Science and Technology Division, who led the research with Raphael Pooser of ORNL’s Computational Sciences and Engineering Division. “We measured the displacement of an atomic force microscope microcantilever with sensitivity better than the standard quantum limit.”

    Unlike today’s classical microscopes, Pooser and Lawrie’s quantum microscope requires quantum theory to describe its sensitivity. The nonlinear amplifiers in ORNL’s microscope generate a special quantum light source known as squeezed light.

    “Imagine a blurry picture,” Pooser said. “It’s noisy and some fine details are hidden. Classical, noisy light prevents you from seeing those details. A ‘squeezed’ version is less blurry and reveals fine details that we couldn’t see before because of the noise.” He added, “We can use a squeezed light source instead of a laser to reduce the noise in our sensor readout.”

    The microcantilever of an atomic force microscope is a miniature diving board that methodically scans a sample and bends when it senses physical changes. With student interns Nick Savino, Emma Batson, Jeff Garcia and Jacob Beckey, Lawrie and Pooser showed that the quantum microscope they invented could measure the displacement of a microcantilever with 50% better sensitivity than is classically possible. For one-second long measurements, the quantum-enhanced sensitivity was 1.7 femtometers – about twice the diameter of a carbon nucleus.

    “Squeezed light sources have been used to provide quantum-enhanced sensitivity for the detection of gravitational waves generated by black hole mergers,” Pooser said. “Our work is helping to translate these quantum sensors from the cosmological scale to the nanoscale.”

    Their approach to quantum microscopy relies on control of waves of light. When waves combine, they can interfere constructively, meaning the amplitudes of peaks add to make the resulting wave bigger. Or they can interfere destructively, meaning trough amplitudes subtract from peak amplitudes to make the resulting wave smaller. This effect can be seen in waves in a pond or in an electromagnetic wave of light like a laser.

    “Interferometers split and then mix two light beams to measure small changes in phase that affect the interference of the two beams when they are recombined,” Lawrie said. “We employed nonlinear interferometers, which use nonlinear optical amplifiers to do the splitting and mixing to achieve classically inaccessible sensitivity.”

    The interdisciplinary study, which is published in Physical Review Letters, is the first practical application of nonlinear interferometry.

    A well-known aspect of quantum mechanics, the Heisenberg uncertainty principle, makes it impossible to define both the position and momentum of a particle with absolute certainty. A similar uncertainty relationship exists for the amplitude and phase of light.

    That fact creates a problem for sensors that rely on classical light sources like lasers: The highest sensitivity they can achieve minimizes the Heisenberg uncertainty relationship with equal uncertainty in each variable. Squeezed light sources reduce the uncertainty in one variable while increasing the uncertainty in the other variable, thus “squeezing” the uncertainty distribution. For that reason, the scientific community has used squeezing to study phenomena both great and small.

    The sensitivity in such quantum sensors is typically limited by optical losses. “Squeezed states are fragile quantum states,” Pooser said. “In this experiment, we were able to circumvent the problem by exploiting properties of entanglement.” Entanglement means independent objects behaving as one. Einstein called it “spooky action at a distance.” In this case, the intensities of the light beams are correlated with each other at the quantum level.

    “Because of entanglement, if we measure the power of one beam of light, it would allow us to predict the power of the other one without measuring it,” he continued. “Because of entanglement, these measurements are less noisy, and that provides us with a higher signal to noise ratio.”

    ORNL’s approach to quantum microscopy is broadly relevant to any optimized sensor that conventionally uses lasers for signal readout. “For instance, conventional interferometers could be replaced by nonlinear interferometry to achieve quantum-enhanced sensitivity for biochemical sensing, dark matter detection or the characterization of magnetic properties of materials,” Lawrie said.

    See the full article here .


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  • richardmitnick 4:05 pm on September 4, 2020 Permalink | Reply
    Tags: "New evidence that the quantum world is even stranger than we thought", Anyons display this behavior only as collective crowds of electrons where many electrons behave as one under very extreme and specific conditions., Anyons maintain a "memory" of their interactions with other quasiparticles by inducing quantum mechanical phase changes., Anyons respond as if they have a fractional charge and even more interestingly create a nontrivial phase change as they braid around one another., , Experimental evidence of quasiparticles called anyons has been found by a team of scientists at Purdue University., In the case of our anyons the phase generated by braiding was 2π/3., Nanotechnology, , , Quasiparticles called "anyons", They are more robust in their properties than other quantum particles. This characteristic is said to be topological.   

    From Purdue University: “New evidence that the quantum world is even stranger than we thought” 

    From Purdue University

    September 4, 2020

    Writer, Media contact:
    Steve Tally
    steve@purdue.edu

    Sources:
    Michael Manfra
    mmanfra@purdue.edu

    James Nakamura
    jnakamur@purdue.edu

    1
    Experimental evidence of quasiparticles called anyons has been found by a team of scientists at Purdue University. Electrical interference in the experiment created a pattern which the researchers called a “pyjama plot”; jumps in the interference pattern were the signature of the presence of anyons. (Purdue University image/James Nakamura.)

    New experimental evidence of a collective behavior of electrons to form “quasiparticles” called “anyons” has been reported by a team of scientists at Purdue University.

    Anyons have characteristics not seen in other subatomic particles, including exhibiting fractional charge and fractional statistics that maintain a “memory” of their interactions with other quasiparticles by inducing quantum mechanical phase changes.

    Postdoctoral research associate James Nakamura, with assistance from research group members Shuang Liang and Geoffrey Gardner, made the discovery while working in the laboratory of professor Michael Manfra. Manfra is a Distinguished Professor of Physics and Astronomy, Purdue’s Bill and Dee O’Brien Chair Professor of Physics and Astronomy, professor of electrical and computer engineering, and professor of materials engineering. Although this work might eventually turn out to be relevant to the development of a quantum computer, for now, Manfra said, it is to be considered an important step in understanding the physics of quasiparticles.

    A research paper on the discovery was published in this week’s Nature Physics.

    Nobel Prize-winning theoretical physicist Frank Wilczek, professor of physics at MIT, gave these quasiparticles the tongue-in-cheek name “anyon” due to their strange behavior because unlike other types of particles, they can adopt “any” quantum phase when their positions are exchanged.

    2
    Scientists at Purdue have announced new experimental evidence of a collective behavior of electrons to form “quasiparticles” called “anyons.” The team was able to demonstrate this behavior by routing the electrons through a specific maze-like etched nanostructure in a nanoscale device called an interferometer. (Purdue University image/James Nakamura.)

    Before the growing evidence of anyons in 2020, physicists had categorized particles in the known world into two groups: fermions and bosons. Electrons are an example of fermions, and photons, which make up light and radio waves, are bosons. One characteristic difference between fermions and bosons is how the particles act when they are looped, or braided, around each other. Fermions respond in one straightforward way, and bosons in another expected and straightforward way.

    Anyons respond as if they have a fractional charge, and even more interestingly, create a nontrivial phase change as they braid around one another. This can give the anyons a type of “memory” of their interaction.

    “Anyons only exist as collective excitations of electrons under special circumstances,” Manfra said. “But they do have these demonstrably cool properties including fractional charge and fractional statistics. It is funny, because you think, ‘How can they have less charge than the elementary charge of an electron?’ But they do.”

    Manfra said that when bosons or fermions are exchanged, they generate a phase factor of either plus one or minus one, respectively.

    “In the case of our anyons the phase generated by braiding was 2π/3,” he said. “That’s different than what’s been seen in nature before.”

    Anyons display this behavior only as collective crowds of electrons, where many electrons behave as one under very extreme and specific conditions, so they are not thought to be found isolated in nature, Nakamura said.

    “Normally in the world of physics, we think about fundamental particles, such as protons and electrons, and all of the things that make up the periodic table,” he said. “But we study the existence of quasiparticles, which emerge from a sea of electrons that are placed in certain extreme conditions.”

    Because this behavior depends on the number of times the particles are braided, or looped, around each other, they are more robust in their properties than other quantum particles. This characteristic is said to be topological [WolframMathWorld] because it depends on the geometry of the system and may eventually lead to much more sophisticated anyon structures that could be used to build stable, topological quantum computers.

    The team was able to demonstrate this behavior by routing the electrons through a specific maze-like etched nanostructure made of gallium arsenide and aluminum gallium arsenide. This device, called an interferometer, confined the electrons to move in a two-dimensional path. The device was cooled to within one-hundredth of a degree from absolute zero (10 millikelvin), and subjected to a powerful 9-Tesla magnetic field. The electrical resistance of the interferometer generated an interference pattern which the researchers called a “pyjama plot.” Jumps in the interference pattern were the signature of the presence of anyons.

    “It is definitely one of the more complex and complicated things to be done in experimental physics,” Chetan Nayak, theoretical physicist at the University of California, Santa Barbara told Science News.

    Nakamura said the facilities at Purdue created the environment for this discovery to happen.

    “We have the technology to grow the gallium arsenide semiconductor that’s needed to realize our electron system. We have the nanofabrication facilities in the Birck Nanotechnology Center to make the interferometer, the device we used in our experiments. In the physics department, we have the ability to measure ultra-low temperatures and to create strong magnetic fields.” he said. “So, we have all of the necessary components that allowed us to make this discovery all here at Purdue. That’s a great thing about doing research here and why we’ve been able to make this progress.”

    Manfra said the next step in the quasiparticle frontier will involve building more complicated interferometers.

    “In the new interferometers we will have the ability to control the location and number of quasiparticles in the chamber,” he said. “Then we will be able to change the number of quasiparticles inside the interferometer on demand and change the interference pattern as we choose.”

    This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under award number DE-SC0020138.

    See the full article here .

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    Stem Education Coalition

    Purdue University is a public research university in West Lafayette, Indiana, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donated land and money to establish a college of science, technology, and agriculture in his name. The first classes were held on September 16, 1874, with six instructors and 39 students.

    The main campus in West Lafayette offers more than 200 majors for undergraduates, over 69 masters and doctoral programs, and professional degrees in pharmacy and veterinary medicine. In addition, Purdue has 18 intercollegiate sports teams and more than 900 student organizations. Purdue is a member of the Big Ten Conference and enrolls the second largest student body of any university in Indiana, as well as the fourth largest foreign student population of any university in the United States.

     
  • richardmitnick 9:27 am on September 1, 2020 Permalink | Reply
    Tags: "Tiny tweezer developed at Vanderbilt can trap molecules on a nanoscale creating powerful research capabilities into cancer metastasis and neurodegenerative diseases", , , Nanotechnology, OTET-opto-thermo-electrohydrodynamic tweezers,   

    From Vanderbilt University: “Tiny tweezer developed at Vanderbilt can trap molecules on a nanoscale, creating powerful research capabilities into cancer metastasis, neurodegenerative diseases” 

    Vanderbilt U Bloc

    From Vanderbilt University

    Aug. 31, 2020
    Marissa Shapiro

    In 2018, one-half of the Nobel Prize was awarded to Arthur Ashkin, the physicist who developed optical tweezers, the use of a tightly focused laser beam to isolate and move micron-scale objects (the size of red blood cells). Now Justus Ndukaife, assistant professor of electrical engineering at Vanderbilt University, has developed the first-ever opto-thermo-electrohydrodynamic tweezers, optical nanotweezers that can trap and manipulate objects on an even smaller scale.

    The article, “Stand-off trapping and manipulation of sub-10 nm objects and biomolecules using opto-thermo-electrohydrodynamic tweezers” was published online in the journal Nature Nanotechnology on August 31, 2020.

    The article was authored by Ndukaife and graduate students Chuchuan Hong and Sen Yang, who are conducting research in Ndukaife’s lab.

    Micron-scale optical tweezers represent a significant advancement in biological research but are limited in the size of the objects they can work with. This is because the laser beam that acts as the pincer of an optical tweezer can only focus the laser light to a certain diameter (about half the laser’s wavelength). In the case of red light with a wavelength of 700 nanometers, the tweezer can focus on and manipulate only objects with a diameter of approximately 350 nanometers or greater using low power. Of course, size is relative, so while a size of 350 nanometers is extremely small, it leaves out the even smaller molecules such as viruses, which come in at 100 nanometers, or DNA and proteins that measure less than 10 nanometers.

    The technique that Ndukaife established with OTET leaves several microns between the laser beam and the molecule it is trapping, another important element of how these new, tiny tweezers work. “We have developed a strategy that enables us to tweeze extremely small objects without exposing them to high-intensity light or heat that can damage a molecule’s function,” Ndukaife said. “The ability to trap and manipulate such small objects gives us the ability to understand the way our DNA and other biological molecules behave in great detail, on a singular level.”

    Before OTET, molecules such as extracellular vesicles could only be isolated using high-speed centrifuges. However, the technology’s high cost has inhibited wide adoption. OTET, on the other hand, has the potential to become broadly available to researchers with smaller budgets. The tweezers can also sort objects based on their size, an approach that is important when looking for specific exosomes, extracellular vesicles secreted by cells that can cause cancers to metastasize. Exosomes range in size from 30 to 150 nanometers, and sorting and investigating specific exosomes has typically proven challenging.

    1
    Nanotweezer (Justus Ndukaife).

    Other applications of OTET that Ndukaife envisions include detecting pathogens by trapping viruses for study and researching proteins that contribute to conditions associated with neurodegenerative diseases such as Alzheimer’s. Both applications could contribute to early detection of disease because the tweezers can effectively capture low levels of molecules, meaning a disease does not have to be full-blown before disease-causing molecules can be researched. OTET can also be combined with other research techniques such as biofluorescence and spectroscopy.

    “The sky is the limit when it comes to the applications of OTET,” said Ndukaife, who collaborated with the Center for Technology Transfer and Commercialization to file a patent on this technology. “I am looking forward to seeing how other researchers harness its capabilities in their work.”

    The research was funded by National Science Foundation (NSF) grant ECCS-1933109 and Vanderbilt University.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Commodore Cornelius Vanderbilt was in his 79th year when he decided to make the gift that founded Vanderbilt University in the spring of 1873.
    The $1 million that he gave to endow and build the university was the commodore’s only major philanthropy. Methodist Bishop Holland N. McTyeire of Nashville, husband of Amelia Townsend who was a cousin of the commodore’s young second wife Frank Crawford, went to New York for medical treatment early in 1873 and spent time recovering in the Vanderbilt mansion. He won the commodore’s admiration and support for the project of building a university in the South that would “contribute to strengthening the ties which should exist between all sections of our common country.”

    McTyeire chose the site for the campus, supervised the construction of buildings and personally planted many of the trees that today make Vanderbilt a national arboretum. At the outset, the university consisted of one Main Building (now Kirkland Hall), an astronomical observatory and houses for professors. Landon C. Garland was Vanderbilt’s first chancellor, serving from 1875 to 1893. He advised McTyeire in selecting the faculty, arranged the curriculum and set the policies of the university.

    For the first 40 years of its existence, Vanderbilt was under the auspices of the Methodist Episcopal Church, South. The Vanderbilt Board of Trust severed its ties with the church in June 1914 as a result of a dispute with the bishops over who would appoint university trustees.

    From the outset, Vanderbilt met two definitions of a university: It offered work in the liberal arts and sciences beyond the baccalaureate degree and it embraced several professional schools in addition to its college. James H. Kirkland, the longest serving chancellor in university history (1893-1937), followed Chancellor Garland. He guided Vanderbilt to rebuild after a fire in 1905 that consumed the main building, which was renamed in Kirkland’s honor, and all its contents. He also navigated the university through the separation from the Methodist Church. Notable advances in graduate studies were made under the third chancellor, Oliver Cromwell Carmichael (1937-46). He also created the Joint University Library, brought about by a coalition of Vanderbilt, Peabody College and Scarritt College.

    Remarkable continuity has characterized the government of Vanderbilt. The original charter, issued in 1872, was amended in 1873 to make the legal name of the corporation “The Vanderbilt University.” The charter has not been altered since.

    The university is self-governing under a Board of Trust that, since the beginning, has elected its own members and officers. The university’s general government is vested in the Board of Trust. The immediate government of the university is committed to the chancellor, who is elected by the Board of Trust.

    The original Vanderbilt campus consisted of 75 acres. By 1960, the campus had spread to about 260 acres of land. When George Peabody College for Teachers merged with Vanderbilt in 1979, about 53 acres were added.

    Vanderbilt’s student enrollment tended to double itself each 25 years during the first century of the university’s history: 307 in the fall of 1875; 754 in 1900; 1,377 in 1925; 3,529 in 1950; 7,034 in 1975. In the fall of 1999 the enrollment was 10,127.

    In the planning of Vanderbilt, the assumption seemed to be that it would be an all-male institution. Yet the board never enacted rules prohibiting women. At least one woman attended Vanderbilt classes every year from 1875 on. Most came to classes by courtesy of professors or as special or irregular (non-degree) students. From 1892 to 1901 women at Vanderbilt gained full legal equality except in one respect — access to dorms. In 1894 the faculty and board allowed women to compete for academic prizes. By 1897, four or five women entered with each freshman class. By 1913 the student body contained 78 women, or just more than 20 percent of the academic enrollment.

    National recognition of the university’s status came in 1949 with election of Vanderbilt to membership in the select Association of American Universities. In the 1950s Vanderbilt began to outgrow its provincial roots and to measure its achievements by national standards under the leadership of Chancellor Harvie Branscomb. By its 90th anniversary in 1963, Vanderbilt for the first time ranked in the top 20 private universities in the United States.

    Vanderbilt continued to excel in research, and the number of university buildings more than doubled under the leadership of Chancellors Alexander Heard (1963-1982) and Joe B. Wyatt (1982-2000), only the fifth and sixth chancellors in Vanderbilt’s long and distinguished history. Heard added three schools (Blair, the Owen Graduate School of Management and Peabody College) to the seven already existing and constructed three dozen buildings. During Wyatt’s tenure, Vanderbilt acquired or built one-third of the campus buildings and made great strides in diversity, volunteerism and technology.

    The university grew and changed significantly under its seventh chancellor, Gordon Gee, who served from 2000 to 2007. Vanderbilt led the country in the rate of growth for academic research funding, which increased to more than $450 million and became one of the most selective undergraduate institutions in the country.

    On March 1, 2008, Nicholas S. Zeppos was named Vanderbilt’s eighth chancellor after serving as interim chancellor beginning Aug. 1, 2007. Prior to that, he spent 2002-2008 as Vanderbilt’s provost, overseeing undergraduate, graduate and professional education programs as well as development, alumni relations and research efforts in liberal arts and sciences, engineering, music, education, business, law and divinity. He first came to Vanderbilt in 1987 as an assistant professor in the law school. In his first five years, Zeppos led the university through the most challenging economic times since the Great Depression, while continuing to attract the best students and faculty from across the country and around the world. Vanderbilt got through the economic crisis notably less scathed than many of its peers and began and remained committed to its much-praised enhanced financial aid policy for all undergraduates during the same timespan. The Martha Rivers Ingram Commons for first-year students opened in 2008 and College Halls, the next phase in the residential education system at Vanderbilt, is on track to open in the fall of 2014. During Zeppos’ first five years, Vanderbilt has drawn robust support from federal funding agencies, and the Medical Center entered into agreements with regional hospitals and health care systems in middle and east Tennessee that will bring Vanderbilt care to patients across the state.

    Today, Vanderbilt University is a private research university of about 6,500 undergraduates and 5,300 graduate and professional students. The university comprises 10 schools, a public policy center and The Freedom Forum First Amendment Center. Vanderbilt offers undergraduate programs in the liberal arts and sciences, engineering, music, education and human development as well as a full range of graduate and professional degrees. The university is consistently ranked as one of the nation’s top 20 universities by publications such as U.S. News & World Report, with several programs and disciplines ranking in the top 10.

    Cutting-edge research and liberal arts, combined with strong ties to a distinguished medical center, creates an invigorating atmosphere where students tailor their education to meet their goals and researchers collaborate to solve complex questions affecting our health, culture and society.

    Vanderbilt, an independent, privately supported university, and the separate, non-profit Vanderbilt University Medical Center share a respected name and enjoy close collaboration through education and research. Together, the number of people employed by these two organizations exceeds that of the largest private employer in the Middle Tennessee region.

     
  • richardmitnick 2:42 pm on August 20, 2020 Permalink | Reply
    Tags: "Stanford scientists slow and steer light with resonant nanoantennas", , “High-Q” resonators, Biosensing, , , Nanotechnology, , ,   

    From Stanford University: Women in STEM-“Stanford scientists slow and steer light with resonant nanoantennas” Jennifer Dionne 

    Stanford University Name
    From Stanford University

    August 17, 2020
    Media Contact
    Ker Than
    Stanford News Service:
    (650) 723-9820
    kerthan@stanford.edu

    Written By Lara Streiff

    Researchers have fashioned ultrathin silicon nanoantennas that trap and redirect light, for applications in quantum computing, LIDAR and even the detection of viruses.

    1
    An artist rendering of a high-Q metasurface beamsplitter. These “high-quality-factor” or “high-Q” resonators could lead to novel ways of manipulating and using light. (Image credit: Riley A. Suhar)

    Light is notoriously fast. Its speed is crucial for rapid information exchange, but as light zips through materials, its chances of interacting and exciting atoms and molecules can become very small. If scientists can put the brakes on light particles, or photons, it would open the door to a host of new technology applications.

    Now, in a paper published on Aug. 17, in Nature Nanotechnology, Stanford scientists demonstrate a new approach to slow light significantly, much like an echo chamber holds onto sound, and to direct it at will. Researchers in the lab of Jennifer Dionne, associate professor of materials science and engineering at Stanford, structured ultrathin silicon chips into nanoscale bars to resonantly trap light and then release or redirect it later. These “high-quality-factor” or “high-Q” resonators could lead to novel ways of manipulating and using light, including new applications for quantum computing, virtual reality and augmented reality; light-based WiFi; and even the detection of viruses like SARS-CoV-2.

    “We’re essentially trying to trap light in a tiny box that still allows the light to come and go from many different directions,” said postdoctoral fellow Mark Lawrence, who is also lead author of the paper. “It’s easy to trap light in a box with many sides, but not so easy if the sides are transparent – as is the case with many Silicon-based applications.”

    Make and manufacture

    Before they can manipulate light, the resonators need to be fabricated, and that poses a number of challenges.

    A central component of the device is an extremely thin layer of silicon, which traps light very efficiently and has low absorption in the near-infrared, the spectrum of light the scientists want to control. The silicon rests atop a wafer of transparent material (sapphire, in this case) into which the researchers direct an electron microscope “pen” to etch their nanoantenna pattern. The pattern must be drawn as smoothly as possible, as these antennas serve as the walls in the echo-chamber analogy, and imperfections inhibit the light-trapping ability.

    “High-Q resonances require the creation of extremely smooth sidewalls that don’t allow the light to leak out,” said Dionne, who is also Senior Associate Vice Provost of Research Platforms/Shared Facilities. “That can be achieved fairly routinely with larger micron-scale structures, but is very challenging with nanostructures which scatter light more.”

    Pattern design plays a key role in creating the high-Q nanostructures. “On a computer, I can draw ultra-smooth lines and blocks of any given geometry, but the fabrication is limited,” said Lawrence. “Ultimately, we had to find a design that gave good-light trapping performance but was within the realm of existing fabrication methods.”

    High quality (factor) applications

    Tinkering with the design has resulted in what Dionne and Lawrence describe as an important platform technology with numerous practical applications.

    The devices demonstrated so-called quality factors up to 2,500, which is two orders of magnitude (or 100 times) higher than any similar devices have previously achieved. Quality factors are a measure describing resonance behavior, which in this case is proportional to the lifetime of the light. “By achieving quality factors in the thousands, we’re already in a nice sweet spot from some very exciting technological applications,” said Dionne.

    For example, biosensing. A single biomolecule is so small that it is essentially invisible. But passing light over a molecule hundreds or thousands of times can greatly increase the chance of creating a detectable scattering effect.

    Dionne’s lab is working on applying this technique to detecting COVID-19 antigens – molecules that trigger an immune response – and antibodies – proteins produced by the immune system in response. “Our technology would give an optical readout like the doctors and clinicians are used to seeing,” said Dionne. “But we have the opportunity to detect a single virus or very low concentrations of a multitude of antibodies owing to the strong light-molecule interactions.” The design of the high-Q nanoresonators also allows each antenna to operate independently to detect different types of antibodies simultaneously.

    Though the pandemic spurred her interest in viral detection, Dionne is also excited about other applications, such as LIDAR – or Light Detection and Ranging, which is laser-based distance measuring technology often used in self-driving vehicles – that this new technology could contribute to. “A few years ago I couldn’t have imagined the immense application spaces that this work would touch upon,” said Dionne. “For me, this project has reinforced the importance of fundamental research – you can’t always predict where fundamental science is going to go or what it’s going to lead to, but it can provide critical solutions for future challenges.”

    This innovation could also be useful in quantum science. For example, splitting photons to create entangled photons that remain connected on a quantum level even when far apart would typically require large tabletop optical experiments with big expensive precisely polished crystals. “If we can do that, but use our nanostructures to control and shape that entangled light, maybe one day we will have an entanglement generator that you can hold in your hand,” Lawrence said. “With our results, we are excited to look at the new science that’s achievable now, but also trying to push the limits of what’s possible.”

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Stanford University campus. No image credit

    Stanford University

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

    Stanford University Seal

     
  • richardmitnick 4:17 pm on August 14, 2020 Permalink | Reply
    Tags: "A Light Bright and Tiny: NIST Scientists Build a Better Nanoscale LED", , Nanotechnology, , , The new device shows an increase in brightness of 100 to 1000 times over conventional tiny submicron-sized LED designs., Their tiny LED had actually become a tiny laser.   

    From NIST- “A Light Bright and Tiny: NIST Scientists Build a Better Nanoscale LED” 


    From NIST

    August 14, 2020
    Chad Boutin
    charles.boutin@nist.gov
    (301) 975-4261

    1
    Credit: B. Nikoobakht, N. Hanacek/NIST.

    A new design for light-emitting diodes (LEDs) developed by a team including scientists at the National Institute of Standards and Technology (NIST) may hold the key to overcoming a long-standing limitation in the light sources’ efficiency. The concept, demonstrated with microscopic LEDs in the lab, achieves a dramatic increase in brightness as well as the ability to create laser light — all characteristics that could make it valuable in a range of large-scale and miniaturized applications.

    The team, which also includes scientists from the University of Maryland, Rensselaer Polytechnic Institute and the IBM Thomas J. Watson Research Center, detailed its work in a paper published today in the peer-reviewed journal Science Advances. Their device shows an increase in brightness of 100 to 1,000 times over conventional tiny, submicron-sized LED designs.

    “It’s a new architecture for making LEDs,” said NIST’s Babak Nikoobakht, who conceived the new design. “We use the same materials as in conventional LEDs. The difference in ours is their shape.”

    LEDs have existed for decades, but the development of bright LEDs won a Nobel prize and ushered in a new era of lighting. However, even modern LEDs have a limitation that frustrates their designers. Up to a point, feeding an LED more electricity makes it shine more brightly, but soon the brightness drops off, making the LED highly inefficient. Called “efficiency droop” by the industry, the issue stands in the way of LEDs being used in a number of promising applications, from communications technology to killing viruses.

    While their novel LED design overcomes efficiency droop, the researchers did not initially set out to solve this problem. Their main goal was to create a microscopic LED for use in very small applications, such as the lab-on-a-chip technology that scientists at NIST and elsewhere are pursuing.

    The team experimented with a whole new design for the part of the LED that shines: Unlike the flat, planar design used in conventional LEDs, the researchers built a light source out of long, thin zinc oxide strands they refer to as fins. (Long and thin are relative terms: Each fin is only about 5 micrometers in length, stretching about a tenth of the way across an average human hair’s breadth.) Their fin array looks like a tiny comb that can extend to areas as large as 1 centimeter or more.

    “We saw an opportunity in fins, as I thought their elongated shape and large side facets might be able to receive more electrical current,” Nikoobakht said. “At first we just wanted to measure how much the new design could take. We started increasing the current and figured we’d drive it until it burned out, but it just kept getting brighter.”

    Their novel design shone brilliantly in wavelengths straddling the border between violet and ultraviolet, generating about 100 to 1,000 times as much power as typical tiny LEDs do. Nikoobakht characterizes the result as a significant fundamental discovery.

    “A typical LED of less than a square micrometer in area shines with about 22 nanowatts of power, but this one can produce up to 20 microwatts,” he said. “It suggests the design can overcome efficiency droop in LEDs for making brighter light sources.”

    “It’s one of the most efficient solutions I have seen,” said Grigory Simin, a professor of electrical engineering at the University of South Carolina who was not involved in the project. “The community has been working for years to improve LED efficiency, and other approaches often have technical issues when applied to submicrometer wavelength LEDs. This approach does the job well.”

    The team made another surprising discovery as they increased the current. While the LED shone in a range of wavelengths at first, its comparatively broad emission eventually narrowed to two wavelengths of intense violet color. The explanation grew clear: Their tiny LED had become a tiny laser.

    “Converting an LED into a laser takes a large effort. It usually requires coupling a LED to a resonance cavity that lets the light bounce around to make a laser,” Nikoobakht said. “It appears that the fin design can do the whole job on its own, without needing to add another cavity.”

    A tiny laser would be critical for chip-scale applications not only for chemical sensing, but also in next-generation hand-held communications products, high-definition displays and disinfection.

    “It’s got a lot of potential for being an important building block,” Nikoobakht said. “While this isn’t the smallest laser people have made, it’s a very bright one. The absence of efficiency droop could make it useful.”

    The research was supported in part by the U.S. Army Cooperative Research Agreement.

    See the full article here.

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    Please help promote STEM in your local schools.

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    NIST Campus, Gaitherberg, MD, USA

    NIST Mission, Vision, Core Competencies, and Core Values

    NIST’s mission

    To promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.
    NIST’s vision

    NIST will be the world’s leader in creating critical measurement solutions and promoting equitable standards. Our efforts stimulate innovation, foster industrial competitiveness, and improve the quality of life.
    NIST’s core competencies

    Measurement science
    Rigorous traceability
    Development and use of standards

    NIST’s core values

    NIST is an organization with strong values, reflected both in our history and our current work. NIST leadership and staff will uphold these values to ensure a high performing environment that is safe and respectful of all.

    Perseverance: We take the long view, planning the future with scientific knowledge and imagination to ensure continued impact and relevance for our stakeholders.
    Integrity: We are ethical, honest, independent, and provide an objective perspective.
    Inclusivity: We work collaboratively to harness the diversity of people and ideas, both inside and outside of NIST, to attain the best solutions to multidisciplinary challenges.
    Excellence: We apply rigor and critical thinking to achieve world-class results and continuous improvement in everything we do.

     
  • richardmitnick 4:07 pm on July 18, 2020 Permalink | Reply
    Tags: , , , , , , , Nanotechnology, , , , SLAC’s upgraded X-ray laser facility produces first light,   

    From SLAC National Accelerator Lab: Updated to add images- “SLAC’s upgraded X-ray laser facility produces first light” 

    From SLAC National Accelerator Lab

    July 17, 2020

    Marking the beginning of the LCLS-II era, the first phase of the major upgrade comes online.

    Just over a decade ago in April 2009, the world’s first hard X-ray free-electron laser (XFEL) produced its first light at the US Department of Energy’s SLAC National Accelerator Laboratory. The Linac Coherent Light Source (LCLS) generated X-ray pulses a billion times brighter than anything that had come before. Since then, its performance has enabled fundamental new insights in a number of scientific fields, from creating “molecular movies” of chemistry in action to studying the structure and motion of proteins for new generations of pharmaceuticals and replicating the processes that create “diamond rain” within giant planets in our solar system.

    The next major step in this field was set in motion in 2013, launching the LCLS-II upgrade project to increase the X-ray laser’s power by thousands of times, producing a million pulses per second compared to 120 per second today. This upgrade is due to be completed within the next two years.

    Today the first phase of the upgrade came into operation, producing an X-ray beam for the first time using one critical element of the newly installed equipment.

    “The LCLS-II project represents the combined effort of five national laboratories from across the US, along with many colleagues from the university community and DOE,” said SLAC Director Chi-Chang Kao. “Today’s success reflects the tremendous value of ongoing partnerships and collaboration that enable us to build unique world-leading tools and capabilities.”

    XFELs work in a two-step process. First, they accelerate a powerful electron beam to nearly the speed of light. They then pass this beam through an exquisitely tuned series of magnets within a device known as an undulator, which converts the electron energy into intense bursts of X-rays. The bursts are just millionths of a billionth of a second long – so short that they can capture the birth of a chemical bond and produce images with atomic resolution. The LCLS-II project will transform both elements of the facility – by installing an entirely new accelerator that uses cryogenic superconducting technology to achieve the unprecedented repetition rates, along with undulators that can provide exquisite control of the X-ray beam.

    Powerful and precise
    1
    Over the past 18 months, the original LCLS undulator system (above) was removed and replaced with two totally new systems that offer dramatic new capabilities (below). (Andy Freeberg/Alberto Gamazo/SLAC National Accelerator Laboratory)


    This video shows how a sequence of carefully designed springs works to counteract the magnetic forces in powerful magnetic devices known as hard X-ray undulator segments. The spring force must exactly match the manetic force in these segments to keep them aligned within millionths of an inch. These segments contain more than 500 magnets and are about 13 feet long. A chain of 32 of these undulator segments will be used at SLAC National Accelerator Laboratory’s LCLS-II X-ray laser to produce X-rays from a powerful electron beam. The video also shows an undulator segment undergoing magnet measurements at Berkeley Lab. (Credits: Matthaeus Leitner and Marilyn Sargent/Berkeley Lab)

    The new undulators were designed and prototyped by DOE’s Argonne National Laboratory and built by Lawrence Berkeley National Laboratory, and have been installed at SLAC over the past year. Today, the first of these systems demonstrated its performance in readiness for the experimental campaigns ahead. Scientists in the SLAC Accelerator Control Room were able to direct the electron beam from the existing LCLS accelerator through the array of magnets in the new “hard X-ray” undulator. Over the course of just a few hours, they produced the first sign of X-rays, and then precisely tuned the configuration to achieve full X-ray laser performance.

    “Reaching the first light is a milestone we all have been looking forward to,” said Henrik von der Lippe, Engineering Division director at Berkeley Lab. “This milestone shows how all the hard work and collaboration has resulted in a scientific facility that will enable new science.”

    He added, “Berkeley Lab’s contribution of the hard X-ray undulator design and fabrication used our experience from providing undulators to science facilities and our longstanding strength in mechanical design. It is rewarding to see the fruits from years of dedicated Engineering Division teams delivering devices that meet all expectations.”

    3
    Images of one of the 21 segments in the soft X-ray undulator (left) and one of the 32 segments in the hard X-ray undulator (right). Each undulator segment is 3.4 meters long. (SLAC National Accelerator Laboratory)

    The scientific impact of the new undulators will be significant. One major advance is that the separation between the magnets can be changed on demand, allowing the wavelength of the emitted X-rays to be tuned to match the needs of experiments. Researchers can use this to pinpoint the behavior of selected atoms in a molecule, which among other things will enhance our ability to track the flow and storage of energy for advanced solar power applications.

    The undulator demonstrated today is optimized for the hard X-ray regime, and will be able to double the peak X-ray energy LCLS can generate. This will provide much higher precision insights into how materials respond to extreme stress at the atomic level and into the emergence of novel quantum phenomena.

    4
    An overlay of LCLS showing the undulator hall, the Front End Enclosure and experimental hall. (SLAC National Accelerator Laboratory)

    Next steps

    Beyond the undulators lies the Front End Enclosure, or FEE, which contains an array of optics, diagnostics and tuning devices that prepare the X-rays for specific experiments. These include the world’s flattest, smoothest mirrors that are a meter in length but vary in height by only an atom’s width across their surface. Over the next few weeks, these optics will be tested in preparation for more than 80 experiments to be conducted by researchers from around the world over the next six months.

    “Today marks the start of the LCLS-II era for X-ray science,” said LCLS Director Mike Dunne. “Our immediate task will be to use this new undulator to investigate the inner workings of the SARS-CoV-2 virus. Then the next couple of years will see an amazing transformation of our facility. Next up will be the soft X-ray undulator, optimized for studying how energy flows between atoms and molecules, and thus the inner workings of novel energy technologies. Beyond this will be the new superconducting accelerator that will increase our X-ray power by many thousands of times. The future is bright, as we like to say in the X-ray laser world.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    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.

     
  • richardmitnick 4:12 pm on July 16, 2020 Permalink | Reply
    Tags: "Unusual nanoparticles could benefit the quest to build a quantum computer", , Nanotechnology, ,   

    From Rutgers University via phys.org: “Unusual nanoparticles could benefit the quest to build a quantum computer” 

    Rutgers smaller
    Our Great Seal.

    From Rutgers University

    via


    phys.org

    1
    The arrows point to titanium dioxide nanocrystals lighting up and blinking (left) and then fading (right). Credit: Tewodros Asefa and Eliska Mikmekova

    Imagine tiny crystals that “blink” like fireflies and can convert carbon dioxide, a key cause of climate change, into fuels.

    A Rutgers-led team has created ultra-small titanium dioxide crystals that exhibit unusual “blinking” behavior and may help to produce methane and other fuels, according to a study in the journal Angewandte Chemie. The crystals, also known as nanoparticles, stay charged for a long time and could benefit efforts to develop quantum computers.

    “Our findings are quite important and intriguing in a number of ways, and more research is needed to understand how these exotic crystals work and to fulfill their potential,” said senior author Tewodros (Teddy) Asefa, a professor in the Department of Chemistry and Chemical Biology in the School of Arts and Sciences at Rutgers University-New Brunswick. He’s also a professor in the Department of Chemical and Biochemical Engineering in the School of Engineering.

    More than 10 million metric tons of titanium dioxide are produced annually, making it one of the most widely used materials, the study notes. It is used in sunscreens, paints, cosmetics and varnishes, for example. It’s also used in the paper and pulp, plastic, fiber, rubber, food, glass and ceramic industries.

    The team of scientists and engineers discovered a new way to make extremely small titanium dioxide crystals. While it’s still unclear why the engineered crystals blink and research is ongoing, the “blinking” is believed to arise from single electrons trapped on titanium dioxide nanoparticles. At room temperature, electrons—surprisingly—stay trapped on nanoparticles for tens of seconds before escaping and then become trapped again and again in a continuous cycle.

    The crystals, which blink when exposed to a beam of electrons, could be useful for environmental cleanups, sensors, electronic devices and solar cells, and the research team will further explore their capabilities.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    rutgers-campus

    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

    As a ’67 graduate of University college, second in my class, I am proud to be a member of

    Alpha Sigma Lamda, National Honor Society of non-tradional students.

     
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