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  • richardmitnick 8:43 pm on July 22, 2021 Permalink | Reply
    Tags: "Laser improves the time resolution of CryoEM", , , , , In cryoEM samples are embedded in vitreous ice-a glass-like form of ice that is obtained when water is frozen so rapidly that crystallization cannot occur., Laser Technology, , Scientists at EPFL’s School of Basic Sciences has developed a cryoEM method that can capture images of protein movements at the microsecond (a millionth of a second) timescale., , The instrument forms images using a beam of electrons instead of light.   

    From Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH): “Laser improves the time resolution of CryoEM” 

    From Swiss Federal Institute of Technology in Lausanne [EPFL-École Polytechnique Fédérale de Lausanne] (CH)

    Nik Papageorgiou

    EPFL scientists have devised a new method that can speed up the real-time observation capabilities of cryo-electron microscopy.

    Cryo-Electron Microscope


    In 2017, Jacques Dubochet, Joachim Frank, and Richard Henderson won the Nobel Prize in Chemistry for their contributions to cryo-electron microscopy (cryoEM), an imaging technique that can capture pictures of biomolecules such as proteins with atomic precision.

    In cryoEM samples are embedded in vitreous ice-a glass-like form of ice that is obtained when water is frozen so rapidly that crystallization cannot occur. With the sample vitrified, high-resolution pictures of their molecular structure can be taken with an electron microscope, an instrument that forms images using a beam of electrons instead of light.

    CryoEM has opened up new dimensions in life sciences, chemistry, and medicine. For example, it was recently used to map the structure of the SARS-CoV-2 spike protein, which is the target of many of the COVID-19 vaccines.

    Proteins constantly change their 3D structure in the cell. These conformational rearrangements are integral for proteins to perform their specialized functions, and take place within millionths to thousandths of a second. Such fast movements are too fast to be observed in real time by current cryoEM protocols, rendering our understanding of proteins incomplete.

    But a team of scientists led by Ulrich Lorenz at EPFL’s School of Basic Sciences has developed a cryoEM method that can capture images of protein movements at the microsecond (a millionth of a second) timescale. The work is published in Chemical Physics Letters.

    The method involves rapidly melting the vitrified sample with a laser pulse. When the ice melts into a liquid, there is a tunable time window in which the protein can be induced to move in the way they do in their natural liquid state in the cell.


    “Generally speaking, warming up a cryo sample causes it to de-vitrify,” says Ulrich Lorenz. “But we can overcome this obstacle by how quickly we melt the sample.”

    After the laser pulse, the sample is re-vitrified in just a few microseconds, trapping the particles in their transient configurations. In this “paused” state, they can now be observed with conventional cryoEM methods.

    “Matching the time resolution of cryoEM to the natural timescale of proteins will allow us to directly study processes that were previously inaccessible,” says Lorenz.

    The team of scientists tested their new method by disassembling proteins after structurally damaging them, and trapping them in partially unraveled configurations.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    EPFL bloc

    EPFL campus

    The Swiss Federal Institute of Technology in Lausanne [EPFL-École polytechnique fédérale de Lausanne] (CH) is a research institute and university in Lausanne, Switzerland, that specializes in natural sciences and engineering. It is one of the two Swiss Federal Institutes of Technology, and it has three main missions: education, research and technology transfer.

    The QS World University Rankings ranks EPFL(CH) 14th in the world across all fields in their 2020/2021 ranking, whereas Times Higher Education World University Rankings ranks EPFL(CH) as the world’s 19th best school for Engineering and Technology in 2020.

    EPFL(CH) is located in the French-speaking part of Switzerland; the sister institution in the German-speaking part of Switzerland is the Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich)](CH) . Associated with several specialized research institutes, the two universities form the Domain of the Swiss Federal Institutes of Technology (ETH Domain) [ETH-Bereich; Domaine des Écoles polytechniques fédérales] (CH) which is directly dependent on the Federal Department of Economic Affairs, Education and Research. In connection with research and teaching activities, EPFL(CH) operates a nuclear reactor CROCUS; a Tokamak Fusion reactor; a Blue Gene/Q Supercomputer; and P3 bio-hazard facilities.

    The roots of modern-day EPFL(CH) can be traced back to the foundation of a private school under the name École spéciale de Lausanne in 1853 at the initiative of Lois Rivier, a graduate of the École Centrale Paris (FR) and John Gay the then professor and rector of the Académie de Lausanne. At its inception it had only 11 students and the offices was located at Rue du Valentin in Lausanne. In 1869, it became the technical department of the public Académie de Lausanne. When the Académie was reorganised and acquired the status of a university in 1890, the technical faculty changed its name to École d’ingénieurs de l’Université de Lausanne. In 1946, it was renamed the École polytechnique de l’Université de Lausanne (EPUL). In 1969, the EPUL was separated from the rest of the University of Lausanne and became a federal institute under its current name. EPFL(CH), like ETH Zürich(CH), is thus directly controlled by the Swiss federal government. In contrast, all other universities in Switzerland are controlled by their respective cantonal governments. Following the nomination of Patrick Aebischer as president in 2000, EPFL(CH) has started to develop into the field of life sciences. It absorbed the Swiss Institute for Experimental Cancer Research (ISREC) in 2008.

    In 1946, there were 360 students. In 1969, EPFL(CH) had 1,400 students and 55 professors. In the past two decades the university has grown rapidly and as of 2012 roughly 14,000 people study or work on campus, about 9,300 of these being Bachelor, Master or PhD students. The environment at modern day EPFL(CH) is highly international with the school attracting students and researchers from all over the world. More than 125 countries are represented on the campus and the university has two official languages, French and English.


    EPFL is organised into eight schools, themselves formed of institutes that group research units (laboratories or chairs) around common themes:

    School of Basic Sciences (SB, Jan S. Hesthaven)

    Institute of Mathematics (MATH, Victor Panaretos)
    Institute of Chemical Sciences and Engineering (ISIC, Emsley Lyndon)
    Institute of Physics (IPHYS, Harald Brune)
    European Centre of Atomic and Molecular Computations (CECAM, Ignacio Pagonabarraga Mora)
    Bernoulli Center (CIB, Nicolas Monod)
    Biomedical Imaging Research Center (CIBM, Rolf Gruetter)
    Interdisciplinary Center for Electron Microscopy (CIME, Cécile Hébert)
    Max Planck-EPFL Centre for Molecular Nanosciences and Technology (CMNT, Thomas Rizzo)
    Swiss Plasma Center (SPC, Ambrogio Fasoli)
    Laboratory of Astrophysics (LASTRO, Jean-Paul Kneib)

    School of Engineering (STI, Ali Sayed)

    Institute of Electrical Engineering (IEL, Giovanni De Micheli)
    Institute of Mechanical Engineering (IGM, Thomas Gmür)
    Institute of Materials (IMX, Michaud Véronique)
    Institute of Microengineering (IMT, Olivier Martin)
    Institute of Bioengineering (IBI, Matthias Lütolf)

    School of Architecture, Civil and Environmental Engineering (ENAC, Claudia R. Binder)

    Institute of Architecture (IA, Luca Ortelli)
    Civil Engineering Institute (IIC, Eugen Brühwiler)
    Institute of Urban and Regional Sciences (INTER, Philippe Thalmann)
    Environmental Engineering Institute (IIE, David Andrew Barry)

    School of Computer and Communication Sciences (IC, James Larus)

    Algorithms & Theoretical Computer Science
    Artificial Intelligence & Machine Learning
    Computational Biology
    Computer Architecture & Integrated Systems
    Data Management & Information Retrieval
    Graphics & Vision
    Human-Computer Interaction
    Information & Communication Theory
    Programming Languages & Formal Methods
    Security & Cryptography
    Signal & Image Processing

    School of Life Sciences (SV, Gisou van der Goot)

    Bachelor-Master Teaching Section in Life Sciences and Technologies (SSV)
    Brain Mind Institute (BMI, Carmen Sandi)
    Institute of Bioengineering (IBI, Melody Swartz)
    Swiss Institute for Experimental Cancer Research (ISREC, Douglas Hanahan)
    Global Health Institute (GHI, Bruno Lemaitre)
    Ten Technology Platforms & Core Facilities (PTECH)
    Center for Phenogenomics (CPG)
    NCCR Synaptic Bases of Mental Diseases (NCCR-SYNAPSY)

    College of Management of Technology (CDM)

    Swiss Finance Institute at EPFL (CDM-SFI, Damir Filipovic)
    Section of Management of Technology and Entrepreneurship (CDM-PMTE, Daniel Kuhn)
    Institute of Technology and Public Policy (CDM-ITPP, Matthias Finger)
    Institute of Management of Technology and Entrepreneurship (CDM-MTEI, Ralf Seifert)
    Section of Financial Engineering (CDM-IF, Julien Hugonnier)

    College of Humanities (CDH, Thomas David)

    Human and social sciences teaching program (CDH-SHS, Thomas David)

    EPFL Middle East (EME, Dr. Franco Vigliotti)[62]

    Section of Energy Management and Sustainability (MES, Prof. Maher Kayal)

    In addition to the eight schools there are seven closely related institutions

    Swiss Cancer Centre
    Center for Biomedical Imaging (CIBM)
    Centre for Advanced Modelling Science (CADMOS)
    École cantonale d’art de Lausanne (ECAL)
    Campus Biotech
    Wyss Center for Bio- and Neuro-engineering
    Swiss National Supercomputing Centre

  • richardmitnick 1:12 pm on July 21, 2021 Permalink | Reply
    Tags: "New imaging technique may boost biology and neuroscience research", , , , Laser Technology, , , The system called De-scattering with Excitation Patterning (or DEEP) is believed to be the first of its kind .   

    From Harvard Gazette (US) : “New imaging technique may boost biology and neuroscience research” 

    From Harvard Gazette (US)


    Harvard University (US)

    July 7, 2021
    Juan Siliezar

    Scientists hope it will let them see inner workings of complex systems.

    Dushan Wadduwage works with a laser in his Northwest lab where he does research on deep tissue imaging. Credit: Jon Chase/Harvard Staff Photographer.

    Microscopists have long sought a way to produce high-quality, deep-tissue imaging of living subjects in a timely fashion. To date, they have had to choose between image quality or speed when looking into the inner workings of complex biological systems.

    A better imaging system would have a powerful impact on researchers in biology and in neuroscience, experts say. Now Dushan N. Wadduwage, a John Harvard Distinguished Science Fellow in imaging at the FAS Center of Advanced Imaging, along with a team from MIT, has detailed a new technique that would make that possible in a report in Science Advances.

    In the paper, the team presents a new process that uses computational imaging to get high-resolution images 100 to 1,000 times faster than other state-of-the-art technologies using complex algorithms and machine learning. The method can shorten a process that often takes months into a matter of days.

    TFM and DEEP-TFM images of a mouse muscle specimen at a 190-um-deep imaging plane. The blue and red channels are respectively nucleus (stained with Hoechst 33342) and F-actin (stained with Alexa Fluor 568 Phalloidin). Courtesy of Dushan N. Wadduwage.

    The system called De-scattering with Excitation Patterning (or DEEP) is believed to be the first of its kind and may one day lead to new understanding of how complicated processes, such as those in the brain, function, because DEEP can capture images other microscopes cannot.

    Because the new system has the potential to actually speed up what they can image along with how fast they can do it, “scientists will be able to image fast processes they haven’t been able to capture before, like what happens when a neuron fires or how the signals move around in the brain,” Wadduwage said. “Also, because it’s technically faster, you can image a larger volume of area at one time, not just a small field of view as you would with a slower imaging system. It’s like being able to look at a much larger picture, and this is very important for neuroscientists and other biologists to actually get better statistics as well as to see what’s happening around the area being imaged.”

    The system works like many other animal-imaging techniques. Near-infrared laser light is used to penetrate deep through biological tissue that scatters the light. That light excites the fluorescent molecules the researchers want to image, and these emit signals that the microscope captures to form an image.

    There have been two main ways these types of images are taken. Point-scanning multiphoton microscopy can penetrate deep into a specimen and capture high-quality images, but this process is extremely slow because the image is formed one point at a time. Capturing a centimeter-sized image, for example, can take months. It also limits studies of fast biological dynamics, such as neurons firing. The other method is called temporal focusing microscopy. This is much faster and can capture images at a wider scale, but it is unable to capture high-resolution images at anything deeper than a few millionths of a meter. The fluorescent light scatters too much, causing the image to degrade when the camera detects it.

    DEEP, however, allows for wide-scale and quick tissue penetration, and produces high-resolution images. The system projects a wide light into the subject as in the temporal microscopy method, but that laser light is in a specific pattern. The computational-imaging algorithm that knows the initial pattern takes in the information gathered to reverse the process when it gets scattered and then reconstructs it, de-scattering the image. This is especially notable since it takes the reconstruction of structural features from millions of measurements to tens and hundreds. DEEP can image hundreds of microns deep through scattering tissue comparable to point-scanning techniques.

    DEEP is still in its early years of development, but is emerging from its proof-of-concept phase.

    “We showed that we can image about 300 microns into the brains of live mice,” Wadduwage said. “But since this is only the first demonstration, almost all aspects of the technique have room for improvement.”

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Harvard University campus

    Harvard University (US) is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s bestknown landmark.

    Harvard University (US) has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

    The Massachusetts colonial legislature, the General Court, authorized Harvard University (US)’s founding. In its early years, Harvard College primarily trained Congregational and Unitarian clergy, although it has never been formally affiliated with any denomination. Its curriculum and student body were gradually secularized during the 18th century, and by the 19th century, Harvard University (US) had emerged as the central cultural establishment among the Boston elite. Following the American Civil War, President Charles William Eliot’s long tenure (1869–1909) transformed the college and affiliated professional schools into a modern research university; Harvard became a founding member of the Association of American Universities in 1900. James B. Conant led the university through the Great Depression and World War II; he liberalized admissions after the war.

    The university is composed of ten academic faculties plus the Radcliffe Institute for Advanced Study. Arts and Sciences offers study in a wide range of academic disciplines for undergraduates and for graduates, while the other faculties offer only graduate degrees, mostly professional. Harvard has three main campuses: the 209-acre (85 ha) Cambridge campus centered on Harvard Yard; an adjoining campus immediately across the Charles River in the Allston neighborhood of Boston; and the medical campus in Boston’s Longwood Medical Area. Harvard University (US)’s endowment is valued at $41.9 billion, making it the largest of any academic institution. Endowment income helps enable the undergraduate college to admit students regardless of financial need and provide generous financial aid with no loans The Harvard Library is the world’s largest academic library system, comprising 79 individual libraries holding about 20.4 million items.

    Harvard University (US) has more alumni, faculty, and researchers who have won Nobel Prizes (161) and Fields Medals (18) than any other university in the world and more alumni who have been members of the U.S. Congress, MacArthur Fellows, Rhodes Scholars (375), and Marshall Scholars (255) than any other university in the United States. Its alumni also include eight U.S. presidents and 188 living billionaires, the most of any university. Fourteen Turing Award laureates have been Harvard affiliates. Students and alumni have also won 10 Academy Awards, 48 Pulitzer Prizes, and 108 Olympic medals (46 gold), and they have founded many notable companies.


    Harvard University (US) was established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. In 1638, it acquired British North America’s first known printing press. In 1639, it was named Harvard College after deceased clergyman John Harvard, an alumnus of the University of Cambridge(UK) who had left the school £779 and his library of some 400 volumes. The charter creating the Harvard Corporation was granted in 1650.

    A 1643 publication gave the school’s purpose as “to advance learning and perpetuate it to posterity, dreading to leave an illiterate ministry to the churches when our present ministers shall lie in the dust.” It trained many Puritan ministers in its early years and offered a classic curriculum based on the English university model—many leaders in the colony had attended the University of Cambridge—but conformed to the tenets of Puritanism. Harvard University (US) has never affiliated with any particular denomination, though many of its earliest graduates went on to become clergymen in Congregational and Unitarian churches.

    Increase Mather served as president from 1681 to 1701. In 1708, John Leverett became the first president who was not also a clergyman, marking a turning of the college away from Puritanism and toward intellectual independence.

    19th century

    In the 19th century, Enlightenment ideas of reason and free will were widespread among Congregational ministers, putting those ministers and their congregations in tension with more traditionalist, Calvinist parties. When Hollis Professor of Divinity David Tappan died in 1803 and President Joseph Willard died a year later, a struggle broke out over their replacements. Henry Ware was elected to the Hollis chair in 1805, and the liberal Samuel Webber was appointed to the presidency two years later, signaling the shift from the dominance of traditional ideas at Harvard to the dominance of liberal, Arminian ideas.

    Charles William Eliot, president 1869–1909, eliminated the favored position of Christianity from the curriculum while opening it to student self-direction. Though Eliot was the crucial figure in the secularization of American higher education, he was motivated not by a desire to secularize education but by Transcendentalist Unitarian convictions influenced by William Ellery Channing and Ralph Waldo Emerson.

    20th century

    In the 20th century, Harvard University (US)’s reputation grew as a burgeoning endowment and prominent professors expanded the university’s scope. Rapid enrollment growth continued as new graduate schools were begun and the undergraduate college expanded. Radcliffe College, established in 1879 as the female counterpart of Harvard College, became one of the most prominent schools for women in the United States. Harvard University (US) became a founding member of the Association of American Universities in 1900.

    The student body in the early decades of the century was predominantly “old-stock, high-status Protestants, especially Episcopalians, Congregationalists, and Presbyterians.” A 1923 proposal by President A. Lawrence Lowell that Jews be limited to 15% of undergraduates was rejected, but Lowell did ban blacks from freshman dormitories.

    President James B. Conant reinvigorated creative scholarship to guarantee Harvard University (US)’s preeminence among research institutions. He saw higher education as a vehicle of opportunity for the talented rather than an entitlement for the wealthy, so Conant devised programs to identify, recruit, and support talented youth. In 1943, he asked the faculty to make a definitive statement about what general education ought to be, at the secondary as well as at the college level. The resulting Report, published in 1945, was one of the most influential manifestos in 20th century American education.

    Between 1945 and 1960, admissions were opened up to bring in a more diverse group of students. No longer drawing mostly from select New England prep schools, the undergraduate college became accessible to striving middle class students from public schools; many more Jews and Catholics were admitted, but few blacks, Hispanics, or Asians. Throughout the rest of the 20th century, Harvard became more diverse.

    Harvard University (US)’s graduate schools began admitting women in small numbers in the late 19th century. During World War II, students at Radcliffe College (which since 1879 had been paying Harvard University (US) professors to repeat their lectures for women) began attending Harvard University (US) classes alongside men. Women were first admitted to the medical school in 1945. Since 1971, Harvard University (US) has controlled essentially all aspects of undergraduate admission, instruction, and housing for Radcliffe women. In 1999, Radcliffe was formally merged into Harvard University (US).

    21st century

    Drew Gilpin Faust, previously the dean of the Radcliffe Institute for Advanced Study, became Harvard University (US)’s first woman president on July 1, 2007. She was succeeded by Lawrence Bacow on July 1, 2018.

  • richardmitnick 4:00 pm on July 17, 2021 Permalink | Reply
    Tags: , , Laser Technology, , , "Future information technologies- Topological materials for ultrafast spintronics", Helmholtz Center for Materials and Energy [Helmholtz-Zentrum Berlin für Materialien und Energie](HZB) (DE), The laws of quantum physics rule the microcosm., In so-called topological insulators only the electrons that can occupy some specific quantum states are free to move like massless particles on the surface., Many questions still need to be answered before spintronic devices can be developed.   

    From Helmholtz Center for Materials and Energy [Helmholtz-Zentrum Berlin für Materialien und Energie](HZB) (DE): “Future information technologies- Topological materials for ultrafast spintronics” 

    From Helmholtz Center for Materials and Energy [Helmholtz-Zentrum Berlin für Materialien und Energie](HZB) (DE)


    Dr. Jaime Sánchez-Barriga
    Tel-(030) 8062 – 15695
    Fax-(030) 8062 – 14673

    Dr. Oliver Jon Clark
    Tel-(030) 8062 – 15695
    Fax-(030) 8062 – 14673

    Press Officer:
    Dr. Antonia Rötger
    Tel-(030) 8062 – 43733
    Fax-(030) 8062 – 42998

    A team led by HZB physicist Dr. Jaime Sánchez-Barriga has gained new insights into the ultrafast response of topological states of matter to femtosecond laser excitation. Using time- and spin-resolved methods at BESSY II, the physicists explored how, after optical excitation, the complex interplay in the behavior of excited electrons in the bulk and on the surface results in unusual spin dynamics.

    BESSY II Synchrotron at Helmholtz Center for Materials and Energy [Helmholtz-Zentrum Berlin für Materialien und Energie](DE)

    The work is an important step on the way to spintronic devices based on topological materials for ultrafast information processing.

    The laws of quantum physics rule the microcosm. They determine, for example, how easily electrons move through a crystal and thus whether the material is a metal, a semiconductor or an insulator. Quantum physics may lead to exotic properties in certain materials: In so-called topological insulators only the electrons that can occupy some specific quantum states are free to move like massless particles on the surface, while this mobility is completely absent for electrons in the bulk. What’s more, the conduction electrons in the “skin” of the material are necessarily spin polarized, and form robust, metallic surface states that could be utilized as channels in which to drive pure spin currents on femtosecond time scales (1 fs= 10^-15 s).

    Exploiting the spin

    These properties open up exciting opportunities to develop new information technologies based on topological materials, such as ultrafast spintronics, by exploiting the spin of the electrons on their surfaces rather than the charge. In particular, optical excitation by femtosecond laser pulses in these materials represents a promising alternative to realize highly efficient, lossless transfer of spin information. Spintronic devices utilizing these properties have the potential of a superior performance, as they would allow to increase the speed of information transport up to frequencies a thousand times faster than in modern electronics.

    However, many questions still need to be answered before spintronic devices can be developed. For example, the details of exactly how the bulk and surface electrons from a topological material respond to the external stimulus i.e., the laser pulse, and the degree of overlap in their collective behaviors on ultrashort time scales.

    The sample: a pure Antimony crystal

    A team led by HZB physicist Dr. Jaime Sánchez-Barriga has now brought new insights into such mechanisms. The team, which has also established a Helmholtz-RSF Joint Research Group in collaboration with colleagues from Lomonosova Moscow State University[Московский государственный университет имени](RU), Moscow, examined single crystals of elemental antimony (Sb), previously suggested to be a topological material. “It is a good strategy to study interesting physics in a simple system, because that’s where we can hope to understand the fundamental principles,” Sánchez-Barriga explains. “The experimental verification of the topological property of this material required us to directly observe its electronic structure in a highly excited state with time, spin, energy and momentum resolutions, and in this way we accessed an unusual electron dynamics,” adds Sánchez-Barriga.

    Probing the electronic structure

    The aim was to understand how fast excited electrons in the bulk and on the surface of Sb react to the external energy input, and to explore the mechanisms governing their response. “By controlling the time delay between the initial laser excitation and the second pulse that allows us to probe the electronic structure, we were able to build up a full time-resolved picture of how excited states leave and return to equilibrium on ultrafast time scales. The unique combination of time and spin-resolved capabilities also allowed us to directly probe the spin-polarization of excited states far out-of-equilibrium”, says Dr. Oliver J. Clark.

    Weight gain detected

    The data show a “kink” structure in transiently occupied energy-momentum dispersion of surface states, which can be interpreted as an increase in effective electron mass. The authors were able to show that this mass enhancement plays a decisive role in determining the complex interplay in the dynamical behaviors of electrons from the bulk and the surface, also depending on their spin, following the ultrafast optical excitation

    Key to control spin polarised currents

    “Our research reveals which essential properties of this class of materials are the key to systematically control the relevant time scales in which lossless spin-polarised currents could be generated and manipulated,” explains Sánchez-Barriga. These are important steps on the way to spintronic devices which based on topological materials possess advanced functionalities for ultrafast information processing.

    Science paper:
    Communications Physics

    See the full article here.


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Helmholtz-Zentrum Berlin für Materialien und Energie (Helmholtz Center for Materials and Energy, [HZB]) is part of the Helmholtz Association of German Research Centres [Helmholtz-Gemeinschaft Deutscher Forschungszentren] (DE). The institute studies the structure and dynamics of materials and investigates solar cell technology. It also runs the third-generation BESSY II synchrotron in Adlershof. Until the end of 2019 it ran the 10 megawatt BER II nuclear research reactor at the Lise Meitner campus in Wannsee.

    The Helmholtz-Zentrum Berlin was created on 1 January 2009 by the merger of Hahn-Meitner-Institut Berlin (HMI) and Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY), thus bringing BESSY into the Helmholtz Association.[4]

    The Hahn-Meitner-Institut Berlin (HMI), named after Otto Hahn and Lise Meitner, was founded 14 March 1959 in Berlin-Wannsee to operate the BER I research reactor that began operation with 50 kW on 24 July 1958. Research originally focused on radiochemistry. In 1971, the federal government took over a 90% share in the HMI.

    The Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY) was founded in 1979. The first synchrotron BESSY I in Berlin-Wilmersdorf began operations in 1982.

  • richardmitnick 3:21 pm on July 17, 2021 Permalink | Reply
    Tags: "The paradox of a free-electron laser without the laser: a new source of coherent radiation", , , , , Common electron-beam based light sources-known as fourth-generation light sources-are based on the free-electron laser (FEL) which uses an undulator to convert electron beam energy into X-rays., Laser Technology, , , The scientists have developed a type of ultra-short wavelength coherent light source that does not require laser action to produce coherence., University of Strathclyde [Oilthigh Shrath Chluaidh] (SCT),   

    From University of Strathclyde [Oilthigh Shrath Chluaidh] (SCT): “The paradox of a free-electron laser without the laser: a new source of coherent radiation” 

    From University of Strathclyde [Oilthigh Shrath Chluaidh] (SCT)

    16 July 2021


    A new way of producing coherent light in the ultra-violet spectral region, which points the way to developing brilliant table-top x-ray sources, has been produced in research led at the University of Strathclyde.

    The scientists have developed a type of ultra-short wavelength coherent light source that does not require laser action to produce coherence. Common electron-beam based light sources-known as fourth-generation light sources-are based on the free-electron laser (FEL) which uses an undulator to convert electron beam energy into X-rays.

    Coherent light sources are powerful tools that enable research in many areas of medicine, biology, material sciences, chemistry and physics.

    Making ultraviolet and X-ray coherent light sources more widely available would transform the way science is done; a university could have one of the devices in a single room, on a table top, for a reasonable price.

    The group is now planning a proof-of-principle experiment in the ultraviolet spectral range to demonstrate this new way of producing coherent light. If successful, it should dramatically accelerate the development of even shorter wavelength coherent sources based on the same principle. The Strathclyde group has set up a facility to investigate these types of sources: the Scottish Centre for the Application of Plasma-based Accelerators (SCAPA), which hosts one of the highest power lasers in the UK.

    The new research has been published in Scientific Reports.

    Professor Dino Jaroszynski, of Strathclyde’s Department of Physics, led the research. He said: “This work significantly advances the state-of-the-art of synchrotron sources by proposing a new method of producing short-wavelength coherent radiation, using a short undulator and attosecond duration electron bunches.

    “This is more compact and less demanding on the electron beam quality than free-electron lasers and could provide a paradigm shift in light sources, which would stimulate a new direction of research. It proposes to use bunch compression – as in chirped pulse amplification lasers – within the undulator to significantly enhance the radiation brightness.

    “The new method presented would be of wide interest to a diverse community developing and using light sources.”

    In FELs, as in all lasers, the intensity of light is amplified by a feedback mechanism that locks the phases of individual radiators, which in this case are “free” electrons. In the FEL, this is achieved by passing a high energy electron beam through the undulator, which is an array of alternating polarity magnets.

    Light emitted from the electrons as they wiggle through the undulator creates a force called the ponderomotive force that bunches the electrons – some are slowed down, some are sped up, which causes bunching, similar to traffic on a motorway periodically slowing and speeding up.

    Electrons passing through the undulator radiate incoherent light if they are uniformly distributed – for every electron that emits light, there is another electron that partially cancels out the light because they radiate out of phase. An analogy of this partial cancelling out is rain on the sea: it produces many small ripples that partially cancel each other out, effectively quelling the waves – reducing their amplitude. In contrast, steady or pulsating wind will cause the waves to amplify through the mutual interaction of the wind with the sea.

    In the FEL, electron bunching causes amplification of the light and the increase in its coherence, which usually takes a long time – thus very long undulators are required. In an X-ray FEL, the undulators can be more than a hundred metres long. The accelerators driving these X-ray FELs are kilometres long, which makes these devices very expensive and some of the largest instruments in the world.

    However, using a free-electron laser to produce coherent radiation is not the only way; a “pre-bunched” beam or ultra-short electron bunch can also be used to achieve exactly the same coherence in a very short undulator that is less than a metre in length. As long as the electron bunch is shorter than the wavelength of the light produced by the undulator, it will automatically produce coherent light – all the light waves will add up or interfere constructively, which leads to very brilliant light with exactly the same properties of light from a laser.

    The researchers have demonstrated theoretically that this can be achieved using a laser-plasma wakefield accelerator, which produces electron bunches that can have a length of a few tens of nanometres. They show that if these ultra-short bunches of high energy electrons pass through a short undulator, they can produce as may photons as a very expensive FEL can produce. Moreover, they have also shown that by producing an electron bunch that has an energy “chirp”, they can ballistically compress the bunch to a very short duration inside the undulator, which provides a unique way of going to even shorter electron bunches and therefore produce even shorter wavelength light.

    The research collaboration also involved the University of Manchester (UK), Pulsar Physics (NL) and the STFC ASTeC group at Daresbury Laboratories. The study has received funding from the EPSRC (Engineering and Physical Sciences Research Council), to support a project named “Lab in a Bubble”.

    See the full article here.


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    The University of Strathclyde [Oilthigh Shrath Chluaidh] (SCT)) is a public research university located in Glasgow, Scotland. Founded in 1796 as the Andersonian Institute, it is Glasgow’s second-oldest university, having received its royal charter in 1964 as the first technological university in the United Kingdom. Taking its name from the historic Kingdom of Strathclyde, it is Scotland’s third-largest university by number of students, with students and staff from over 100 countries.

    The institution was named University of the Year 2012 by Times Higher Education and again in 2019, becoming the first university to receive this award twice. The annual income of the institution for 2019–20 was £334.8 million of which £81.2 million was from research grants and contracts, with an expenditure of £298.8 million. It is one of the 39 old universities in the UK comprising the distinctive second cluster of elite universities after Oxbridge.


    In 2011 the University’s Advanced Forming Research Centre was announced as a leading partner in the first UK-wide Technology Strategy Board Catapult Centre. The Government also announced that the University is to lead the UK-wide EPSRC Centre for Innovative Manufacturing in Continuous Manufacturing and Crystallisation.

    The University has become the base for the first Fraunhofer Centre to be established in the UK. Fraunhofer-Gesellschaft, Europe’s largest organisation for contract research, is creating the new Fraunhofer Centre for Applied Photonics in collaboration with Strathclyde, for research in sectors including healthcare, security, energy and transport.

    Strathclyde was chosen in 2012 as the exclusive European partner university for South Korea’s global research and commercialisation programme – the Global Industry-Academia Cooperation Programme, funded by South Korea’s Ministry of Knowledge and Economics.

    In 2012 the University became a key partner in its second UK Catapult Centre. Plans for the Catapult Centre for Offshore Renewable Energy were announced at Strathclyde by Business Secretary Vince Cable. The University has also become a partner in the Industrial Doctorate Centre for Offshore Renewable Energy, which is one of 11 doctoral centres at Strathclyde.

    Engineers at the University are leading the €4 million, Europe-wide Stardust project, a research-based training network investigating the removal of space debris and the deflection of asteroids.

    Strathclyde has become part of the new ESRC Enterprise Research Centre, a £2.9 million venture generating world-class research to help stimulate growth for small and medium-sized enterprises.

    The University has centres in pharmacy, drug delivery and development, micro and ultrasonic engineering, biophotonics and photonics, biomedical engineering, medical devices, new therapies,prosthetics and orthotics, public health history, law, crime and justice and social work. The University is involved in 11 partnerships with other universities through the Scottish Funding Councils’ Research Pooling Programme, covering areas such as engineering, life sciences, energy, marine science and technology, physics, chemistry, computer sciences and economics.

    Several Strathclyde staff have been elected to Fellowships in the Royal Societies of Edinburgh and London.

  • richardmitnick 11:18 am on July 14, 2021 Permalink | Reply
    Tags: "The hidden culprit killing lithium-metal batteries from the inside", , , Determining cause-of-death for a coin battery is surprisingly difficult., , For decades scientists have tried to make reliable lithium-metal batteries., Laser Technology, , The scientists used a microscope that has a laser to mill through a battery’s outer casing., The separator is completely shredded., The team found a surprising second culprit: a hard buildup formed as a byproduct of the battery’s internal chemical reactions. Every time the battery recharged the byproduct called solid electrolyte, These high-performance storage cells hold 50% more energy than their prolific lithium-ion cousins but higher failure rates and safety problems like fires and explosions., This is what battery researchers have always wanted to see., When the team reviewed images of the batteries’ insides they expected to find needle-shaped deposits of lithium spanning the battery.   

    From DOE’s Sandia National Laboratories (US) : “The hidden culprit killing lithium-metal batteries from the inside” 

    From DOE’s Sandia National Laboratories (US)

    July 14, 2021

    Troy Rummler

    First-of-their-kind snapshots reveal byproduct crippling powerful, experimental cells.

    Sandia National Laboratories scientists Katie Harrison, left, and Katie Jungjohann have pioneered a new way to look inside batteries to learn how and why they fail. Photo by Bret Latter.

    For decades scientists have tried to make reliable lithium-metal batteries. These high-performance storage cells hold 50% more energy than their prolific, lithium-ion cousins but higher failure rates and safety problems like fires and explosions have crippled commercialization efforts. Researchers have hypothesized why the devices fail, but direct evidence has been sparse.

    Now, the first nanoscale images ever taken inside intact, lithium-metal coin batteries (also called button cells or watch batteries) challenge prevailing theories and could help make future high-performance batteries, such as for electric vehicles, safer, more powerful and longer lasting.

    “We’re learning that we should be using separator materials tuned for lithium metal,” said battery scientist Katie Harrison, who leads Sandia National Laboratories’ team for improving the performance of lithium-metal batteries.

    Sandia scientists, in collaboration with Thermo Fisher Scientific Inc., the University of Oregon (US) and DOE’s Lawrence Berkeley National Laboratory (US), published the images recently in ACS Energy Letters.


    Figure 1. Scanning electron micrographs of intact angled-sections of high-rate cycled Li-metal half cells. (a) Uncycled cell, including: stainless-steel cap, Cu current collector, stack of two Celgard 2325 separators, Li metal, bottom Cu current collector, and lower stainless-steel disc, (b) 1st Li plating, (c) 1st Li stripping, (d) 11th plating, (e) 51st plating, and (f) 101st plating step. White arrows indicate cracks in the SEI matrix and gray regions indicate structures out-of-plane from the cut face.

    Figure 2. Electrochemical performance of the 101st Li plating sample. (a) Capacity of the plating and stripping cycles, for Li plating at a high rate of 1.88 mA/cm2 up to the 101st plating step. (b) Coulombic efficiency of each full cycle, exhibiting the battery’s ability to efficiently recapture Li, even after the quantity of plated Li significantly decreases at ∼75 cycles. Capacity (c) and Coulombic efficiency (d) of the plating and stripping cycles at a low rate of 0.47 mA/cm2 to a capacity of 1.88 mAh/cm2. (e) Scanning electron micrograph of an intact angled-section of the 101st Li plating low-rate cycled half-cell. The brown layer at the top of the image is the stainless-steel cap, and the gray contrast indicates structures out-of-plane from the cut face.

    Figure 3. Scanning electron micrographs of high-rate cycled angled-sections showing failure within two stacked Celgard 2325 separators. (a) Uncycled cell and (b) higher-magnification image of the separator porosity (with the lighter contrast indicating iron redeposition from laser ablation), (c) 1st Li plating, (d) 1st Li stripping, (e) 11th plating, (f) 51st plating, and (g) 101st plating step.

    Figure 4. Schematic short-circuit mechanism for conductive Li pathways through the polymeric separator via SEI formation and subsequent deformation of the separator. SEI formed during the current plating step is colored yellow; SEI that formed in a prior step is colored gray.

    Internal byproduct builds up, kills batteries

    The team repeatedly charged and discharged lithium coin cells with the same high-intensity electric current that electric vehicles need to charge. Some cells went through a few cycles, while others went through more than a hundred cycles. Then, the cells were shipped to Thermo Fisher Scientific in Hillsboro, Oregon, for analysis.

    In this new, false-color image of a lithium-metal test battery produced by Sandia National Laboratories, high-rate charging and recharging red lithium metal greatly distorts the green separator, creating tan reaction byproducts, to the surprise of scientists. Image by Katie Jungjohann.

    When the team reviewed images of the batteries’ insides they expected to find needle-shaped deposits of lithium spanning the battery. Most battery researchers think that a lithium spike forms after repetitive cycling and that it punches through a plastic separator between the anode and the cathode, forming a bridge that causes a short. But lithium is a soft metal, so scientists have not understood how it could get through the separator.

    Harrison’s team found a surprising second culprit: a hard buildup formed as a byproduct of the battery’s internal chemical reactions. Every time the battery recharged the byproduct called solid electrolyte interphase grew. Capping the lithium, it tore holes in the separator, creating openings for metal deposits to spread and form a short. Together, the lithium deposits and the byproduct were much more destructive than previously believed, acting less like a needle and more like a snowplow.

    “The separator is completely shredded,” Harrison said, adding that this mechanism has only been observed under fast charging rates needed for electric vehicle technologies, but not slower charging rates.

    As Sandia scientists think about how to modify separator materials, Harrison says that further research also will be needed to reduce the formation of byproducts.

    Scientists pair lasers with cryogenics to take ‘cool’ images

    Determining cause-of-death for a coin battery is surprisingly difficult. The trouble comes from its stainless-steel casing. The metal shell limits what diagnostics, like X-rays, can see from the outside, while removing parts of the cell for analysis rips apart the battery’s layers and distorts whatever evidence might be inside.

    “We have different tools that can study different components of a battery, but really we haven’t had a tool that can resolve everything in one image,” said Katie Jungjohann, a Sandia nanoscale imaging scientist at the Center for Integrated Nanotechnologies. The center is a user facility jointly operated by Sandia and Los Alamos national laboratories.

    She and her collaborators used a microscope that has a laser to mill through a battery’s outer casing. They paired it with a sample holder that keeps the cell’s liquid electrolyte frozen at temperatures between minus 148 and minus 184 degrees Fahrenheit (minus 100 and minus 120 degrees Celsius, respectively). The laser creates an opening just large enough for a narrow electron beam to enter and bounce back onto a detector, delivering a high-resolution image of the battery’s internal cross section with enough detail to distinguish the different materials.

    The original demonstration instrument, which was the only such tool in the United States at the time, was built and still resides at a Thermo Fisher Scientific laboratory in Oregon. An updated duplicate now resides at Sandia. The tool will be used broadly across Sandia to help solve many materials and failure-analysis problems.

    “This is what battery researchers have always wanted to see,” Jungjohann said.

    The research was funded by Sandia’s Laboratory Directed Research and Development program and the Department of Energy.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Sandia Campus.

    DOE’s Sandia National Laboratories (US) managed and operated by the National Technology and Engineering Solutions of Sandia (a wholly owned subsidiary of Honeywell International), is one of three National Nuclear Security Administration(US) research and development laboratories in the United States. Their primary mission is to develop, engineer, and test the non-nuclear components of nuclear weapons and high technology. Headquartered in Central New Mexico near the Sandia Mountains, on Kirtland Air Force Base in Albuquerque, Sandia also has a campus in Livermore, California, next to DOE’sLawrence Livermore National Laboratory(US), and a test facility in Waimea, Kauai, Hawaii.

    It is Sandia’s mission to maintain the reliability and surety of nuclear weapon systems, conduct research and development in arms control and nonproliferation technologies, and investigate methods for the disposal of the United States’ nuclear weapons program’s hazardous waste.

    Other missions include research and development in energy and environmental programs, as well as the surety of critical national infrastructures. In addition, Sandia is home to a wide variety of research including computational biology; mathematics (through its Computer Science Research Institute); materials science; alternative energy; psychology; MEMS; and cognitive science initiatives.

    Sandia formerly hosted ASCI Red, one of the world’s fastest supercomputers until its recent decommission, and now hosts ASCI Red Storm supercomputer, originally known as Thor’s Hammer.

    Sandia is also home to the Z Machine.

    The Z Machine is the largest X-ray generator in the world and is designed to test materials in conditions of extreme temperature and pressure. It is operated by Sandia National Laboratories to gather data to aid in computer modeling of nuclear guns. In December 2016, it was announced that National Technology and Engineering Solutions of Sandia, under the direction of Honeywell International, would take over the management of Sandia National Laboratories starting on May 1, 2017.

  • richardmitnick 7:40 pm on July 13, 2021 Permalink | Reply
    Tags: "Custom-made MIT tool probes materials at the nanoscale", , , , Laser Technology, , , Modern materials research has greatly benefited from advanced experimental tools., , Near-field infrared nanoscope and spectroscope, , Scanning Nearfield Optical Microscope or s-SNOM., Scattering-type scanning nearfield optical microscope   

    From Massachusetts Institute of Technology (US) : “Custom-made MIT tool probes materials at the nanoscale” 

    MIT News

    From Massachusetts Institute of Technology (US)

    July 13, 2021
    Elizabeth A. Thomson

    A scattering-type scanning nearfield optical microscope offers advantages to researchers across many disciplines.

    Assistant Professor Long Ju (center) and colleagues have built a new, customized version of a laboratory tool known as near-field infrared nanoscopy and spectroscopy for MIT users. It and an earlier version, also in Ju’s lab, are the first such tools at the Institute. Here graduate student Matthew Yeung, Professor Ju, and postdoc Zhengguang Lu stand beside the new tool. Credit: Long Ju.

    An MIT physicist has built a new instrument of interest to MIT researchers across a wide range of disciplines because it can quickly and relatively inexpensively determine a variety of important characteristics of a material at the nanoscale. It’s capable of not only determining internal properties of a material, such as how that material’s electrical or optical conductivity changes over exquisitely short distances, but also visualizing individual molecules, like proteins.

    “Modern materials research has greatly benefited from advanced experimental tools,” says Long Ju, an assistant professor in the Department of Physics. Ju is an expert on an emerging instrument that combines nanoscopy — the ability to see things at the nanoscale — with spectroscopy, which probes materials by exploring their interactions with light.

    The tool, known as a near-field infrared nanoscope and spectroscope (it is also known as a scattering-type scanning nearfield optical microscope, or s-SNOM), is available commercially. However, “it’s rather challenging for new users, which limits the applications of the technique,” says Ju.

    So the Ju group built its own version of the tool — the first s-SNOM at MIT — and in May completed a second, more advanced version with additional functions. Now both instruments are available to the MIT community, and the Ju group is on hand to provide assistance to MIT users and to develop new functionalities. Ju encourages MIT colleagues to contact him with potential applications or questions.

    “It’s exciting because it’s a platform that can, in principle, host many different materials systems and extract new information from each,” says Ju, who is also affiliated with MIT’s Materials Research Laboratory. “It’s also a platform for some of the best minds in the world — MIT researchers — to conceive things beyond what can be done on a standard s-SNOM.”

    The new tool is based on atomic force microscopy (AFM), in which an extremely sharp metallic tip with a radius of only 20 nanometers, or billionths of a meter, is scanned across the surface of a material. AFM creates a map of the physical features, or topography, of a surface, of such high resolution that it can identify “mountains” or “valleys” less than a nanometer in height or depth.

    Adding light

    Ju is adding light to the equation. Focusing an infrared laser on the AFM tip turns that tip into an antenna “just like the antenna on a television that’s used to receive signals,” he says. And that, in turn, greatly enhances interactions between the light and the material beneath the tip. The back-scattered light collected from those interactions can be analyzed to reveal much more about the surface than would be possible with a conventional AFM.

    The result: “You can get an image of your sample with three orders of magnitude better spatial resolution than that of conventional infrared measurements,” says Ju. In earlier work reported in Nature, he and colleagues published images of graphene taken with AFM and with the new tool. There are features in common between the two, but the near-field image is riddled with bright lines that are not visible in the AFM image. They are domain walls, or the interfaces between two different sections of a material. Those interfaces are key to understanding a material’s structure and properties.

    Images of similar detail can be captured with transmission electron microscopy (TEM), but TEM has some drawbacks. For example, it must be operated in an ultra-high vacuum, and samples must be extremely thin for suspension on a film or membrane. “The former limits the experimental throughput, while the latter is not compatible with most materials,” says Ju.

    In contrast, the near-field nanoscope “can be operated in air, does not require suspension of the sample, and you can work on most solid substrates,” Ju says.

    Many applications

    Ju notes that the near-field tool can not only provide high-resolution images of heights; the analysis of back-scattered light from the machine’s tip can also give important information about a material’s internal properties. For example, it can tell metals from insulators. It can also distinguish between materials with the same chemical composition but different internal structures (think diamond versus pencil lead).

    In an example he describes as “especially cool,” Ju says that the instrument could even be used to watch a material transition from insulator to superconductor as the temperature is changed. It is also capable of monitoring chemical reactions on the nanoscale.

    Ju also notes that the new tool can be operated in different ways for different purposes. For example, he said, the tip of the tool can either be scanned across a surface while being irradiated with a set wavelength of light, or the tip can be parked over a certain area and probed with light of different wavelengths. Different wavelengths of light interact differently with different materials, giving even more information about a given material’s composition or other characteristics.

    Ju, who came to MIT in 2019, is thoroughly enjoying meeting other MIT researchers who might have applications for his machine. “It’s exciting to work with people from different research areas. You can work together to generate new ideas at the cutting edge.”

    This work is sponsored by MIT’s Materials Research Laboratory.

    See the full article here .

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    MIT Seal

    USPS “Forever” postage stamps celebrating Innovation at MIT.

    MIT Campus

    Massachusetts Institute of Technology (US) is a private land-grant research university in Cambridge, Massachusetts. The institute has an urban campus that extends more than a mile (1.6 km) alongside the Charles River. The institute also encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory, the Bates Center, and the Haystack Observatory, as well as affiliated laboratories such as the Broad and Whitehead Institutes.

    Founded in 1861 in response to the increasing industrialization of the United States, Massachusetts Institute of Technology (US) adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. It has since played a key role in the development of many aspects of modern science, engineering, mathematics, and technology, and is widely known for its innovation and academic strength. It is frequently regarded as one of the most prestigious universities in the world.

    As of December 2020, 97 Nobel laureates, 26 Turing Award winners, and 8 Fields Medalists have been affiliated with MIT as alumni, faculty members, or researchers. In addition, 58 National Medal of Science recipients, 29 National Medals of Technology and Innovation recipients, 50 MacArthur Fellows, 80 Marshall Scholars, 3 Mitchell Scholars, 22 Schwarzman Scholars, 41 astronauts, and 16 Chief Scientists of the U.S. Air Force have been affiliated with Massachusetts Institute of Technology (US) . The university also has a strong entrepreneurial culture and MIT alumni have founded or co-founded many notable companies. Massachusetts Institute of Technology (US) is a member of the Association of American Universities (AAU).

    Foundation and vision

    In 1859, a proposal was submitted to the Massachusetts General Court to use newly filled lands in Back Bay, Boston for a “Conservatory of Art and Science”, but the proposal failed. A charter for the incorporation of the Massachusetts Institute of Technology, proposed by William Barton Rogers, was signed by John Albion Andrew, the governor of Massachusetts, on April 10, 1861.

    Rogers, a professor from the University of Virginia (US), wanted to establish an institution to address rapid scientific and technological advances. He did not wish to found a professional school, but a combination with elements of both professional and liberal education, proposing that:

    “The true and only practicable object of a polytechnic school is, as I conceive, the teaching, not of the minute details and manipulations of the arts, which can be done only in the workshop, but the inculcation of those scientific principles which form the basis and explanation of them, and along with this, a full and methodical review of all their leading processes and operations in connection with physical laws.”

    The Rogers Plan reflected the German research university model, emphasizing an independent faculty engaged in research, as well as instruction oriented around seminars and laboratories.

    Early developments

    Two days after Massachusetts Institute of Technology (US) was chartered, the first battle of the Civil War broke out. After a long delay through the war years, MIT’s first classes were held in the Mercantile Building in Boston in 1865. The new institute was founded as part of the Morrill Land-Grant Colleges Act to fund institutions “to promote the liberal and practical education of the industrial classes” and was a land-grant school. In 1863 under the same act, the Commonwealth of Massachusetts founded the Massachusetts Agricultural College, which developed as the University of Massachusetts Amherst (US)). In 1866, the proceeds from land sales went toward new buildings in the Back Bay.

    Massachusetts Institute of Technology (US) was informally called “Boston Tech”. The institute adopted the European polytechnic university model and emphasized laboratory instruction from an early date. Despite chronic financial problems, the institute saw growth in the last two decades of the 19th century under President Francis Amasa Walker. Programs in electrical, chemical, marine, and sanitary engineering were introduced, new buildings were built, and the size of the student body increased to more than one thousand.

    The curriculum drifted to a vocational emphasis, with less focus on theoretical science. The fledgling school still suffered from chronic financial shortages which diverted the attention of the MIT leadership. During these “Boston Tech” years, Massachusetts Institute of Technology (US) faculty and alumni rebuffed Harvard University (US) president (and former MIT faculty) Charles W. Eliot’s repeated attempts to merge MIT with Harvard College’s Lawrence Scientific School. There would be at least six attempts to absorb MIT into Harvard. In its cramped Back Bay location, MIT could not afford to expand its overcrowded facilities, driving a desperate search for a new campus and funding. Eventually, the MIT Corporation approved a formal agreement to merge with Harvard, over the vehement objections of MIT faculty, students, and alumni. However, a 1917 decision by the Massachusetts Supreme Judicial Court effectively put an end to the merger scheme.

    In 1916, the Massachusetts Institute of Technology (US) administration and the MIT charter crossed the Charles River on the ceremonial barge Bucentaur built for the occasion, to signify MIT’s move to a spacious new campus largely consisting of filled land on a one-mile-long (1.6 km) tract along the Cambridge side of the Charles River. The neoclassical “New Technology” campus was designed by William W. Bosworth and had been funded largely by anonymous donations from a mysterious “Mr. Smith”, starting in 1912. In January 1920, the donor was revealed to be the industrialist George Eastman of Rochester, New York, who had invented methods of film production and processing, and founded Eastman Kodak. Between 1912 and 1920, Eastman donated $20 million ($236.6 million in 2015 dollars) in cash and Kodak stock to MIT.

    Curricular reforms

    In the 1930s, President Karl Taylor Compton and Vice-President (effectively Provost) Vannevar Bush emphasized the importance of pure sciences like physics and chemistry and reduced the vocational practice required in shops and drafting studios. The Compton reforms “renewed confidence in the ability of the Institute to develop leadership in science as well as in engineering”. Unlike Ivy League schools, Massachusetts Institute of Technology (US) catered more to middle-class families, and depended more on tuition than on endowments or grants for its funding. The school was elected to the Association of American Universities (US)in 1934.

    Still, as late as 1949, the Lewis Committee lamented in its report on the state of education at Massachusetts Institute of Technology (US) that “the Institute is widely conceived as basically a vocational school”, a “partly unjustified” perception the committee sought to change. The report comprehensively reviewed the undergraduate curriculum, recommended offering a broader education, and warned against letting engineering and government-sponsored research detract from the sciences and humanities. The School of Humanities, Arts, and Social Sciences and the MIT Sloan School of Management were formed in 1950 to compete with the powerful Schools of Science and Engineering. Previously marginalized faculties in the areas of economics, management, political science, and linguistics emerged into cohesive and assertive departments by attracting respected professors and launching competitive graduate programs. The School of Humanities, Arts, and Social Sciences continued to develop under the successive terms of the more humanistically oriented presidents Howard W. Johnson and Jerome Wiesner between 1966 and 1980.

    Massachusetts Institute of Technology (US)‘s involvement in military science surged during World War II. In 1941, Vannevar Bush was appointed head of the federal Office of Scientific Research and Development and directed funding to only a select group of universities, including MIT. Engineers and scientists from across the country gathered at Massachusetts Institute of Technology (US)’s Radiation Laboratory, established in 1940 to assist the British military in developing microwave radar. The work done there significantly affected both the war and subsequent research in the area. Other defense projects included gyroscope-based and other complex control systems for gunsight, bombsight, and inertial navigation under Charles Stark Draper’s Instrumentation Laboratory; the development of a digital computer for flight simulations under Project Whirlwind; and high-speed and high-altitude photography under Harold Edgerton. By the end of the war, Massachusetts Institute of Technology (US) became the nation’s largest wartime R&D contractor (attracting some criticism of Bush), employing nearly 4000 in the Radiation Laboratory alone and receiving in excess of $100 million ($1.2 billion in 2015 dollars) before 1946. Work on defense projects continued even after then. Post-war government-sponsored research at MIT included SAGE and guidance systems for ballistic missiles and Project Apollo.

    These activities affected Massachusetts Institute of Technology (US) profoundly. A 1949 report noted the lack of “any great slackening in the pace of life at the Institute” to match the return to peacetime, remembering the “academic tranquility of the prewar years”, though acknowledging the significant contributions of military research to the increased emphasis on graduate education and rapid growth of personnel and facilities. The faculty doubled and the graduate student body quintupled during the terms of Karl Taylor Compton, president of Massachusetts Institute of Technology (US) between 1930 and 1948; James Rhyne Killian, president from 1948 to 1957; and Julius Adams Stratton, chancellor from 1952 to 1957, whose institution-building strategies shaped the expanding university. By the 1950s, Massachusetts Institute of Technology (US) no longer simply benefited the industries with which it had worked for three decades, and it had developed closer working relationships with new patrons, philanthropic foundations and the federal government.

    In late 1960s and early 1970s, student and faculty activists protested against the Vietnam War and Massachusetts Institute of Technology (US)’s defense research. In this period Massachusetts Institute of Technology (US)’s various departments were researching helicopters, smart bombs and counterinsurgency techniques for the war in Vietnam as well as guidance systems for nuclear missiles. The Union of Concerned Scientists was founded on March 4, 1969 during a meeting of faculty members and students seeking to shift the emphasis on military research toward environmental and social problems. Massachusetts Institute of Technology (US) ultimately divested itself from the Instrumentation Laboratory and moved all classified research off-campus to the MIT (US) Lincoln Laboratory facility in 1973 in response to the protests. The student body, faculty, and administration remained comparatively unpolarized during what was a tumultuous time for many other universities. Johnson was seen to be highly successful in leading his institution to “greater strength and unity” after these times of turmoil. However six Massachusetts Institute of Technology (US) students were sentenced to prison terms at this time and some former student leaders, such as Michael Albert and George Katsiaficas, are still indignant about MIT’s role in military research and its suppression of these protests. (Richard Leacock’s film, November Actions, records some of these tumultuous events.)

    In the 1980s, there was more controversy at Massachusetts Institute of Technology (US) over its involvement in SDI (space weaponry) and CBW (chemical and biological warfare) research. More recently, Massachusetts Institute of Technology (US)’s research for the military has included work on robots, drones and ‘battle suits’.

    Recent history

    Massachusetts Institute of Technology (US) has kept pace with and helped to advance the digital age. In addition to developing the predecessors to modern computing and networking technologies, students, staff, and faculty members at Project MAC, the Artificial Intelligence Laboratory, and the Tech Model Railroad Club wrote some of the earliest interactive computer video games like Spacewar! and created much of modern hacker slang and culture. Several major computer-related organizations have originated at MIT since the 1980s: Richard Stallman’s GNU Project and the subsequent Free Software Foundation were founded in the mid-1980s at the AI Lab; the MIT Media Lab was founded in 1985 by Nicholas Negroponte and Jerome Wiesner to promote research into novel uses of computer technology; the World Wide Web Consortium standards organization was founded at the Laboratory for Computer Science in 1994 by Tim Berners-Lee; the MIT OpenCourseWare project has made course materials for over 2,000 Massachusetts Institute of Technology (US) classes available online free of charge since 2002; and the One Laptop per Child initiative to expand computer education and connectivity to children worldwide was launched in 2005.

    Massachusetts Institute of Technology (US) was named a sea-grant college in 1976 to support its programs in oceanography and marine sciences and was named a space-grant college in 1989 to support its aeronautics and astronautics programs. Despite diminishing government financial support over the past quarter century, MIT launched several successful development campaigns to significantly expand the campus: new dormitories and athletics buildings on west campus; the Tang Center for Management Education; several buildings in the northeast corner of campus supporting research into biology, brain and cognitive sciences, genomics, biotechnology, and cancer research; and a number of new “backlot” buildings on Vassar Street including the Stata Center. Construction on campus in the 2000s included expansions of the Media Lab, the Sloan School’s eastern campus, and graduate residences in the northwest. In 2006, President Hockfield launched the MIT Energy Research Council to investigate the interdisciplinary challenges posed by increasing global energy consumption.

    In 2001, inspired by the open source and open access movements, Massachusetts Institute of Technology (US) launched OpenCourseWare to make the lecture notes, problem sets, syllabi, exams, and lectures from the great majority of its courses available online for no charge, though without any formal accreditation for coursework completed. While the cost of supporting and hosting the project is high, OCW expanded in 2005 to include other universities as a part of the OpenCourseWare Consortium, which currently includes more than 250 academic institutions with content available in at least six languages. In 2011, Massachusetts Institute of Technology (US) announced it would offer formal certification (but not credits or degrees) to online participants completing coursework in its “MITx” program, for a modest fee. The “edX” online platform supporting MITx was initially developed in partnership with Harvard and its analogous “Harvardx” initiative. The courseware platform is open source, and other universities have already joined and added their own course content. In March 2009 the Massachusetts Institute of Technology (US) faculty adopted an open-access policy to make its scholarship publicly accessible online.

    Massachusetts Institute of Technology (US) has its own police force. Three days after the Boston Marathon bombing of April 2013, MIT Police patrol officer Sean Collier was fatally shot by the suspects Dzhokhar and Tamerlan Tsarnaev, setting off a violent manhunt that shut down the campus and much of the Boston metropolitan area for a day. One week later, Collier’s memorial service was attended by more than 10,000 people, in a ceremony hosted by the Massachusetts Institute of Technology (US) community with thousands of police officers from the New England region and Canada. On November 25, 2013, Massachusetts Institute of Technology (US) announced the creation of the Collier Medal, to be awarded annually to “an individual or group that embodies the character and qualities that Officer Collier exhibited as a member of the Massachusetts Institute of Technology (US) community and in all aspects of his life”. The announcement further stated that “Future recipients of the award will include those whose contributions exceed the boundaries of their profession, those who have contributed to building bridges across the community, and those who consistently and selflessly perform acts of kindness”.

    In September 2017, the school announced the creation of an artificial intelligence research lab called the MIT-IBM Watson AI Lab. IBM will spend $240 million over the next decade, and the lab will be staffed by MIT and IBM scientists. In October 2018 MIT announced that it would open a new Schwarzman College of Computing dedicated to the study of artificial intelligence, named after lead donor and The Blackstone Group CEO Stephen Schwarzman. The focus of the new college is to study not just AI, but interdisciplinary AI education, and how AI can be used in fields as diverse as history and biology. The cost of buildings and new faculty for the new college is expected to be $1 billion upon completion.

    The Caltech/MIT Advanced aLIGO (US) was designed and constructed by a team of scientists from California Institute of Technology (US), Massachusetts Institute of Technology (US), and industrial contractors, and funded by the National Science Foundation (US) .

    MIT/Caltech Advanced aLigo .

    It was designed to open the field of gravitational-wave astronomy through the detection of gravitational waves predicted by general relativity. Gravitational waves were detected for the first time by the LIGO detector in 2015. For contributions to the LIGO detector and the observation of gravitational waves, two Caltech physicists, Kip Thorne and Barry Barish, and Massachusetts Institute of Technology (US) physicist Rainer Weiss won the Nobel Prize in physics in 2017. Weiss, who is also an Massachusetts Institute of Technology (US) graduate, designed the laser interferometric technique, which served as the essential blueprint for the LIGO.

    The mission of Massachusetts Institute of Technology (US) 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 Massachusetts Institute of Technology (US) community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

  • richardmitnick 4:36 pm on July 10, 2021 Permalink | Reply
    Tags: "Scientists develop a new geometry for a neutron source platform for NIF", , , , Laser Technology, , University of Rochester(US) Laboratory for Laser Energetics   

    From DOE’s Lawrence Livermore National Laboratory (US) : “Scientists develop a new geometry for a neutron source platform for NIF” 

    From DOE’s Lawrence Livermore National Laboratory (US)


    Michael Padilla

    In the inverted-corona platform, laser beams are pointed onto the inside walls via laser entrance holes. Graphic provided by Matthias Hohenberger.

    The National Ignition Facility (NIF) [below] at Lawrence Livermore National Laboratory (LLNL) has added a new tool to its growing list of capabilities.

    A team of scientists has demonstrated a new geometry for a neutron source platform for NIF, called the inverted-corona platform, which does not rely on spherically symmetric laser irradiation.

    This new tool has significantly less-stringent laser-symmetry requirements than conventional laser driven neutron sources on NIF. In this technique, laser energy is used to heat the inner surface of a millimeter-scale capsule. The wall material expands and launches a centrally stagnating shock into the gas fill to heat the gas to fusion conditions.

    “This platform has relevance to applications in effects testing or forensics,” said Matthias Hohenberger, LLNL staff scientist. “We have an experiment scheduled in 2022 for exploring applications as a neutron backlighter, and as a neutron source for nuclear-cross-section measurements with sample materials attached to the outside of the capsule.”

    Hohenberger said there are other potential applications in basic science, and is one-of-a-kind in its geometry flexibility. “It also represents a challenging problem to simulate because of the relatively low plasma density,” he said. “So we’re using it to test mix models in state-of-the-art simulation codes, and to train junior scientists.”

    The work, highlighted in a paper in Review of Scientific Instruments, presents a novel neutron-source platform for NIF. Typically, NIF neutron platforms are based on the spherical compression of a capsule filled with deuterium and tritium (DT) fuel, thus achieving the pressures and temperatures necessary for the DT to undergo fusion reactions. This is achieved using either indirect-drive intertial confinement fusion (ICF) platforms or directly-driven exploding pushers. In these platforms, the incident laser results in a pushing action from the outside of the capsule, accelerating the capsule wall inwards — either from the X-rays generated in the hohlraum, or from the laser incident on the capsule itself. That means performance is highly sensitive to drive asymmetries, as they result in an uneven push of the wall, and eventual mixing of fuel and wall material into the hot spot, said Hohenberger, who is the lead author of the paper.

    “This can, and does, affect fusion performance,” he said. “It also means that the wall composition must be controlled tightly. Even small impurities in the wall, thickness variations or even surface roughness will affect the performance and neutron yield.”

    Pointing lasers onto the inside of capsule wall

    Hohenberger said in this new scheme, which was tested on the OMEGA laser and the NIF, the laser beams are pointed through laser entrance holes onto the inside wall of a ~5-millimeter diameter, gas-filled (D2 or DT) capsule.

    This causes the wall material to ablate inwards, which then launches a converging shock wave into the gas fill. The shock stagnates on center and heats the gas fill to fusion conditions (similarly to an exploding pusher). However, because the laser beams are incident onto the inside wall, the capsule wall itself is pushed outwards and away from the center, and the fusion performance is dominated by the ablatively-driven shock.

    Hohenberger said this work has two key advantages. First, it decouples the wall composition from the neutron source and significantly relaxes requirements on capsule quality such as thickness uniformity, material purity and surface roughness, because the wall does not mix with the hot spot since it is pushed out rather than inwards. Second, the performance is highly insensitive to low-mode asymmetries. That means it is possible to have laser beams incident from only one side, rather than symmetrically distributed around the target, without a reduction in neutron yield.

    The platform was successfully demonstrated in experiments on both the OMEGA laser and NIF.

    The work was funded through LLNL’s Laboratory Directed Research and Development program.

    In addition to Hohenberger, co-authors include Nathan Meezan, Bob Heeter, Rick Heredia, Nino Landen, Andrew MacKinnon and Warren Hsing from LLNL; Will Riedel and Mark Cappelli from Stanford University (US); Neel Kabadi and Richard Petrasso from Massachusetts Institute of Technology (US); Chad Forrest from the Laboratory for Energetics (US) at the University of Rochester (US); Loosineh Aghaian, Mike Farrell and Claudia Shuldberg from General Atomics; and Franziska Treffert and Siegfried Glenzer from DOE’s SLAC National Accelerator Laboratory.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

    DOE’s Lawrence Livermore National Laboratory (LLNL) (US) is an American federal research facility in Livermore, California, United States, founded by the University of California-Berkeley (US) in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System (US). In 2012, the laboratory had the synthetic chemical element livermorium named after it.

    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.” Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    The Laboratory is located on a one-square-mile (2.6 km^2) site at the eastern edge of Livermore. It also operates a 7,000 acres (28 km2) remote experimental test site, called Site 300, situated about 15 miles (24 km) southeast of the main lab site. LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees.

    LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore, an offshoot of the existing UC Radiation Laboratory at Berkeley. It was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence, director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility.

    The new laboratory was sited at a former naval air station of World War II. It was already home to several UC Radiation Laboratory projects that were too large for its location in the Berkeley Hills above the UC campus, including one of the first experiments in the magnetic approach to confined thermonuclear reactions (i.e. fusion). About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than an urban university campus.

    Lawrence tapped 32-year-old Herbert York, a former graduate student of his, to run Livermore. Under York, the Lab had four main programs: Project Sherwood (the magnetic-fusion program), Project Whitney (the weapons-design program), diagnostic weapon experiments (both for the DOE’s Los Alamos National Laboratory(US) and Livermore laboratories), and a basic physics program. York and the new lab embraced the Lawrence “big science” approach, tackling challenging projects with physicists, chemists, engineers, and computational scientists working together in multidisciplinary teams. Lawrence died in August 1958 and shortly after, the university’s board of regents named both laboratories for him, as the Lawrence Radiation Laboratory.

    Historically, the DOE’s Lawrence Berkeley National Laboratory (US) and Livermore laboratories have had very close relationships on research projects, business operations, and staff. The Livermore Lab was established initially as a branch of the Berkeley laboratory. The Livermore lab was not officially severed administratively from the Berkeley lab until 1971. To this day, in official planning documents and records, Lawrence Berkeley National Laboratory is designated as Site 100, Lawrence Livermore National Lab as Site 200, and LLNL’s remote test location as Site 300.

    The laboratory was renamed Lawrence Livermore Laboratory (LLL) in 1971. On October 1, 2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the synthetic chemical element livermorium named after it. The LLNS takeover of the laboratory has been controversial. In May 2013, an Alameda County jury awarded over $2.7 million to five former laboratory employees who were among 430 employees LLNS laid off during 2008.The jury found that LLNS breached a contractual obligation to terminate the employees only for “reasonable cause.” The five plaintiffs also have pending age discrimination claims against LLNS, which will be heard by a different jury in a separate trial.[6] There are 125 co-plaintiffs awaiting trial on similar claims against LLNS. The May 2008 layoff was the first layoff at the laboratory in nearly 40 years.

    On March 14, 2011, the City of Livermore officially expanded the city’s boundaries to annex LLNL and move it within the city limits. The unanimous vote by the Livermore city council expanded Livermore’s southeastern boundaries to cover 15 land parcels covering 1,057 acres (4.28 km^2) that comprise the LLNL site. The site was formerly an unincorporated area of Alameda County. The LLNL campus continues to be owned by the federal government.


  • richardmitnick 4:38 pm on July 7, 2021 Permalink | Reply
    Tags: "Quantum Laser Turns Energy Loss into Gain​", , , Laser Technology, Parity-time reversal symmetry,   

    From KAIST-Korea Advanced Institute of Science and Technology [한국과학기술원 카이스트] (KR): “Quantum Laser Turns Energy Loss into Gain​” 

    From KAIST-Korea Advanced Institute of Science and Technology [한국과학기술원 카이스트] (KR)


    A new laser that generates quantum particles can recycle lost energy for highly efficient, low threshold laser applications.

    Exciton-polaritonic PT symmetry: Direct coupling between upward- and downward-polariton modes in a six-fold symmetric microcavity with loss manipulation leads to PT-symmetry breaking with low-threshold phase transition.

    Scientists at KAIST have fabricated a laser system that generates highly interactive quantum particles at room temperature. Their findings, published in the journal Nature Photonics, could lead to a single microcavity laser system that requires lower threshold energy as its energy loss increases.

    The system, developed by KAIST physicist Yong-Hoon Cho and colleagues, involves shining light through a single hexagonal-shaped microcavity treated with a loss-modulated silicon nitride substrate. The system design leads to the generation of a polariton laser at room temperature, which is exciting because this usually requires cryogenic temperatures.

    The researchers found another unique and counter-intuitive feature of this design. Normally, energy is lost during laser operation. But in this system, as energy loss increased, the amount of energy needed to induce lasing decreased. Exploiting this phenomenon could lead to the development of high efficiency, low threshold lasers for future quantum optical devices.

    “This system applies a concept of quantum physics known as parity-time reversal symmetry,” explains Professor Cho. “This is an important platform that allows energy loss to be used as gain. It can be used to reduce laser threshold energy for classical optical devices and sensors, as well as quantum devices and controlling the direction of light.”

    The key is the design and materials. The hexagonal microcavity divides light particles into two different modes: one that passes through the upward-facing triangle of the hexagon and another that passes through its downward-facing triangle. Both modes of light particles have the same energy and path but don’t interact with each other.

    However, the light particles do interact with other particles called excitons, provided by the hexagonal microcavity, which is made of semiconductors. This interaction leads to the generation of new quantum particles called polaritons that then interact with each other to generate the polariton laser. By controlling the degree of loss between the microcavity and the semiconductor substrate, an intriguing phenomenon arises, with the threshold energy becoming smaller as energy loss increases. This research was supported by the Samsung Science and Technology Foundation and Korea’s National Research Foundation.

    See the full article here.


    Please help promote STEM in your local schools.

    Stem Education Coalition

    <a href="http:// KAIST-Korea Advanced Institute of Science and Technology [한국과학기술원 카이스트] (KR) is the first and top science and technology university in Korea. KAIST has been the gateway to advanced science and technology, innovation, and entrepreneurship, and our graduates have been key players behind Korea’ innovations. KAIST will continue to pursue advances in science and technology as well as the economic development of Korea and beyond.

    KAIST educates, researches, and takes the lead in innovations to serve the happiness and prosperity of humanity. KAIST fosters talents who exhibit creativity, embrace challenges, and possess caring minds in creating knowledge and translating it into transformative innovation.

  • richardmitnick 1:51 pm on July 7, 2021 Permalink | Reply
    Tags: "Researchers Discover Origin of Near Ultraviolet and Visible Absorption Characteristics of Ti: sapphire Laser Crystals", , , , Laser Technology,   

    From Chinese Academy of Sciences [中国科学院] (CN) : “Researchers Discover Origin of Near Ultraviolet and Visible Absorption Characteristics of Ti: sapphire Laser Crystals” 

    From Chinese Academy of Sciences [中国科学院] (CN)

    Fig. 1. (a) The supercell structure of Al2O3, (b) the interstitial Ti3+, Al vacancy and substitutional Ti3+ models, and their transformation process, (c) the line-contact Ti3+-Ti3+ ion pair model, (d) the face-contact Ti3+-Ti3+ ion pair model, (e) the point-contact Ti4+-Ti3+ ion pair model (Al vacancy is considered as the charge compensation mechanism of Ti4+). (Image by SIOM)

    Recently, a research group from the Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) carried out a theoretical research on the origin of Ti: sapphire laser crystal in near ultraviolet and visible regions using the first principles method based on density functional theory. Related research results have been published in Materials Today Communications on June 4.

    Ti: sapphire, also known as Ti-doped α-Al2O3 single crystal, is a very important laser crystal material. At present, it is also one of the key materials in a class of super-intense, ultrafast, and tunable laser devices. Since the laser properties of it was reported in 1982, the origin of some suspicious absorption phenomena in the optical absorption band of Ti: sapphire has been one of the focuses of attention and research.

    According to the wavelength distribution, these questionable absorption bands can be roughly divided into three regions: the near ultraviolet absorption band with a peak at 390 nm, the visible absorption band with multi-peak configuration and small bumps, and the residual infrared absorption band overlapped with the laser emission band.

    In this study, the researchers performed a systematic theoretical study on the suspicious absorption phenomenon of Ti: sapphire in near ultraviolet and visible regions.

    Through the analysis of the crystal structure of alumina and the calculation of the electronic and optical properties of the possible single Ti doping defect models and Ti ion pair defect models in Ti: sapphire, they pointed out that when there is an Al vacancy near the interstitial Ti3+, the interstitial Ti3+ will enter the Al vacancy through structural relaxation, and finally form defect equivalent to the substitutional Ti3+.

    The charge transfer transition of substitutional Ti3+ ion’s 3d electron from Ti 3d orbital to Al 3s3p orbital is the main reason for the near ultraviolet absorption band, and the calculated absorption spectra are in good agreement with the experimental spectra.

    Moreover, the multi-peak configuration and bumps of the visible absorption band are mainly caused by the contribution of the line-contact Ti3+-Ti3+, face-contact Ti3+-Ti3+, and point-contact Ti4+-Ti3+ ion pairs.

    In addition, the researchers provided a more comprehensive understanding of the multi-peak configuration and bumps of visible absorption bands from the perspective of ligand field theory and thermal activation.

    This study not only reveals the origin of the suspicious absorption characteristics in Ti-doped Al2O3 crystal but also provides ideas for the study of defects and properties of similar transition metal ions doped oxides having corundum structure.

    This work was supported by the Strategic Priority Research Program of CAS, the National Key R&D Program of China, the National Natural Science Foundation of China, etc.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Chinese Academy of Sciences [中国科学院] (CN) is the linchpin of China’s drive to explore and harness high technology and the natural sciences for the benefit of China and the world. Comprising a comprehensive research and development network, a merit-based learned society and a system of higher education, CAS brings together scientists and engineers from China and around the world to address both theoretical and applied problems using world-class scientific and management approaches.

    Since its founding, CAS has fulfilled multiple roles — as a national team and a locomotive driving national technological innovation, a pioneer in supporting nationwide S&T development, a think tank delivering S&T advice and a community for training young S&T talent.

    Now, as it responds to a nationwide call to put innovation at the heart of China’s development, CAS has further defined its development strategy by emphasizing greater reliance on democratic management, openness and talent in the promotion of innovative research. With the adoption of its Innovation 2020 programme in 2011, the academy has committed to delivering breakthrough science and technology, higher caliber talent and superior scientific advice. As part of the programme, CAS has also requested that each of its institutes define its “strategic niche” — based on an overall analysis of the scientific progress and trends in their own fields both in China and abroad — in order to deploy resources more efficiently and innovate more collectively.

    As it builds on its proud record, CAS aims for a bright future as one of the world’s top S&T research and development organizations.

  • richardmitnick 9:17 pm on July 6, 2021 Permalink | Reply
    Tags: "What is a photon?", , , Laser Technology, , ,   

    From Symmetry: “What is a photon?” 

    Symmetry Mag

    From Symmetry

    Amanda Solliday
    Kathryn Jepsen

    The fundamental particle of light is both ordinary and full of surprises.

    Credit: Single-Photon Workshop 2019. http://www.eventideib.polimi.it/en/events/single-photon-workshop-2019/

    What physicists refer to as photons, other people might just call light. As quanta of light, photons are the smallest possible packets of electromagnetic energy. If you are reading this article on a screen or a page, streams of photons are carrying the images of the words to your eyes.

    In science, photons are used for more than just illumination.

    “They’re ubiquitous,” says Richard Ruiz, a research associate at the Institute of Nuclear Physics – Polish Academy of Sciences[Instytut Fizyki Jądrowej-polska akademia nauk](PL], and a theorist looking for new physics at the Large Hadron Collider.

    “Photons are everywhere in particle physics, so you almost forget about them.”

    The photon has fueled centuries of discovery, and it remains an important tool today.

    From wave, to particle, to boson

    People have investigated the nature of light since ancient times, with early insights coming from philosophers and scholars in Egypt, Mesopotamia, India and Greece. Between the late 17th and early 20th centuries, scientists went back and forth on the answer to one question in particular: Does light behave as a particle or as a wave?

    In 1690, Christiaan Huygens published Traité de la Lumière, his treatise on light. In it, he described light as being made up of waves that moved through the ether, which was thought to permeate space.

    Isaac Newton declared in his 1704 book Opticks that he disagreed. When light reflects off of a surface, it acts like a bouncing ball; the angle at which it approaches the surface is equal to the angle at which it bounces off. Newton argued that this phenomenon, among other things, could be explained if light were made up of particles, which he called “corpuscules.”

    A glass prism refracts a beam of white light into a rainbow of colors. Newton noticed that when the light was then refracted again, through a second prism, it did not divide any further; the rainbow colors stayed the same.

    Newton said this could be explained by assuming that white light was made up of many different corpuscules of different sizes. Red light was made up of the biggest corpuscules; violet was made up of the smallest. Newton said their different sizes caused the corpuscules to be pulled through the glass at different, accelerated speeds. This spread them out, producing the rainbow of colors that could not be broken down further by a second prism.

    Newton’s corpuscular model had a significant drawback, though.

    When light travels through a small hole, it spreads out just like ripples in water. Newton’s corpuscular model couldn’t explain this behavior, and Huygens’ wave model could.

    Still, scientists were generally inclined to dismiss Huygens and listen to Newton—he did write Principia, one of the most important books in the history of science, after all.

    But Huygens’ model received some support in 1801, when Thomas Young conducted the double slit experiment. In the experiment, Young sent a beam of light through two small holes, side-by-side, and found that the light passing through them formed a particular pattern. At regular intervals the intersecting ripples emanating from the two holes interfered either constructively—combining to make brighter light—or destructively—canceling one another out. Just like waves.

    About five decades later, another experiment put Huygens’ model definitively in the lead.

    In 1850, Léon Foucalt compared the speed of light through air with the speed of light through water and found that, contrary to Newton’s assertions, light did not move faster in the denser medium. Instead, just like a wave would, it slowed down.

    Eleven years later, James Clerk Maxwell published On Physical Lines of Force, in which he predicted the existence of electromagnetic waves. Maxwell noted their similarity to lightwaves, leading him to conclude that the two were one and the same.

    It seemed that Huygens’ wave model had won the day. But in 1900, Max Planck came up with an idea that would spark a brand new concept of light.

    Planck explained some puzzling behaviors of radiation by describing the energy of electromagnetic waves as divided into individual packets. In 1905, Albert Einstein built on Planck’s concept of energy packets and finally settled the corpuscule-versus-wave debate—by declaring it a tie.

    As Einstein explained, light behaves as both a particle and a wave, with the energy of each particle of light corresponding to the frequency of the wave.

    His evidence came from studies of the photoelectric effect—the way in which light knocked electrons loose from metal. If light traveled only in a continuous wave, then shining a light on metal for long enough would always dislodge an electron, because the energy the light transferred to the electron would accumulate over time.

    But the photoelectric effect didn’t work that way. In 1902 Philipp Lenard had observed that only light above a certain energy—or lightwaves above a certain frequency—could pry an electron loose from the metal. And it seemed to do so on contact, immediately.

    In this case, the light was acting more like a particle, an individual packet of energy.

    Still convinced of the wave model of light, Robert Millikan set out to disprove Einstein’s hypothesis. Millikan took careful measurements of the relationship between the light and electrons involved in the photoelectric effect. To his surprise, he confirmed each of Einstein’s predictions.

    Einstein’s study of the photoelectric effect earned him his sole Nobel Prize in 1921.

    In 1923, Arthur Compton provided additional support for Einstein’s model of light. Compton aimed high-energy light at materials, and he successfully predicted the angles at which electrons released by the collisions would scatter. He did it by presuming the light would act like tiny billiard balls.

    Chemist Gilbert Lewis came up with a name for these billiard balls. In a 1926 letter to the journal Nature, he called them “photons.”

    The way that scientists think about photons has continued to evolve in more recent years. For one, the photon is now known as a “gauge boson.”

    Gauge bosons are force-carrying particles that enable matter particles to interact via the fundamental forces. Atoms, for example, stick together because the positively charged protons in their nuclei exchange photons with the negatively charged electrons that orbit them—an interaction via the electromagnetic force.

    Secondly, the photon is now thought of as a particle, a wave, and an excitation—kind of like a wave—in a quantum field.

    A quantum field, such as the electromagnetic field, is a kind of energy and potential spread throughout space. Physicists think of every particle as an excitation of a quantum field.

    “I like to think of a quantum field as a calm pond surface where you don’t see anything,” Ruiz says. “Then you put a pebble on the surface, and the water pops up a bit. That’s a particle.”

    Photons as a tool

    Radio waves and microwaves; infrared and ultraviolet light; X-rays and gamma rays: All of these are light, and all of them are made up of photons.

    Photons are at work all around you. They travel through connected fibers to deliver internet, cable and cell phone signals. They are used in plastics upcycling, to break down objects into small building blocks that can be used in new materials. They are used in hospitals, in beams that target and destroy cancerous tissues.

    And they are key to all kinds of scientific research.

    Photons are essential in cosmology: the study of the past, present and future of the universe. Scientists study stars by examining the electromagnetic radiation they emit, such as radio waves and visible light. Astronomers develop maps of our galaxy and its neighbors by imaging the microwave sky. They detect space dust that blocks their view of distant stars by detecting its infrared light.

    Scientists collect strong signals, in the form of ultraviolet radiation, X-rays, and gamma rays emitted by energetic objects from our galaxy and beyond. And they detect weak signals, such as the faint pattern of light known as the cosmic microwave background, which serves as a record of the state of the universe seconds after the Big Bang.

    Photons also remain important in physics.

    In 2012, scientists at the Large Hadron Collider discovered the Higgs boson by studying its decay into pairs of photons.

    Physicist Donna Strickland won a share of the Nobel Prize in Physics in 2018 for her work developing ultrashort, high-intensity laser pulses, formed from highly focused high-energy light.

    Machines called light sources create intense beams of X-rays, ultraviolet light and infrared light to help scientists break down the steps of the fastest chemical processes and examine materials in molecular detail.

    “Across the electromagnetic spectrum, photons can provide us with so much information about the world,” says Jennifer Dionne, associate professor of materials science and engineering at Stanford University (US).

    Dionne conducts research in the field of nanophotonics, a subfield of physics in which scientists control light and study its interactions with molecules and nano-sized structures. Among other projects, her lab uses photons to up the effectiveness of catalysts, substances used to kick off high-efficiency chemical reactions.

    “Light—photons—are a reagent in chemistry that people don’t always think about,” Dionne says. “People often think about adding new chemicals to enable a certain reaction or controlling the temperature or pH of a solution. Light can bring a whole new dimension and an entirely new tool kit.”

    Some physicists are even looking for new types of photons. Theoretical “dark photons” would serve as a new kind of gauge bosons, mediating the interactions between particles of dark matter.

    “Photons are always full of surprises,” Dionne says

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

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