Tag Archives: electron

Flexing Fingers for Micro-Robotics: Berkeley Lab Scientists Create a Powerful, Microscale Actuator

By Guest PostDecember 18, 2012Scienceartificial muscles, beckoning finger, berkeley lab, chromium metal layer, chun cheng, electron, electronic behaviors, flex, human muscle cells, junqiao wu, kai liu, kevin wang, metal, microactuator, microfluidics, micron, microscale actuator, natural application, oxide material, phase transitions, phenomena, phillip m. duxbury, piezoelectric device, piezoelectric technology, ramamoorthy ramesh, subhendra d mahanti, Technology, temperature variation, university of california, vanadium dioxide, zhenting cheng

Berkeley, Calif., Dec. 2012 — Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley, have developed an elegant and powerful new microscale actuator that can flex like a tiny beckoning finger. Based on an oxide material that expands and contracts dramatically in response to a small temperature variation, the actuators are smaller than the width of a human hair and are promising for microfluidics, drug delivery, and artificial muscles.

“We believe our microactuator is more efficient and powerful than any current microscale actuation technology, including human muscle cells,” says Berkeley Lab and UC Berkeley scientist Junqiao Wu. “What’s more, it uses this very interesting material—vanadium dioxide—and tells us more about the fundamental materials science of phase transitions.” (more…)

Measuring Table-Top Accelerators’ State-of-the-Art Beams

By Guest PostNovember 4, 2012Scienceaccelerator, berkeley lab, boundary, chen lin, coherent, cotr, density modulation, electron, electron beam, electron laser, fusion research, high density, high energy, hydrogen gas, initial momentum, jeroen van tilborg, laser plasma acceleration, light regime, light source, loasis, longitudinal slice, lpa, modulation, momentum, mylar foil, optical, particle count, photon pattern, plasma, pulse, radiation, transition, ultrathin, vacuum, wim leemans, xray window

Studies by Berkeley Lab scientists of electron beam quality in laser plasma accelerators include novel tests for slice-energy spread

Part Two: Slicing through the electron beam

Wim Leemans of Berkeley Lab’s Accelerator and Fusion Research Division heads LOASIS, the Laser and Optical Accelerator Systems Integrated Studies, an oasis indeed for students pursuing graduate studies in laser plasma acceleration (LPA). Among the most promising applications of future table-top accelerators are new kinds of light sources, in which their electron beams power free electron lasers.

“If our LPA electron bunches had good enough quality for free electron lasers – and were really only femtoseconds long – we should see a particular kind of radiation called coherent optical transition radiation, or COTR,” Leemans says. “So I assigned my doctoral student Chen Lin, a graduate of Peking University and now a postdoc there, to find it.” (more…)

How Silver Turns People Blue

By Guest PostOctober 27, 2012Scienceabsorb, acidic environment, agnes kane, antimicrobial, argyria, base membrane, bioavailable salt, bloodstream, brown researcher, brown university, charged ions, disorder, electron, environmental impact, exposure scenario, frances liu, germs, gi tract, grayish blue, health tonics, jingyu liu, medical treatment, nanoparticle, particle, photochemical reaction, protein, robert hurt, salt ion, silver, silver atom, silver salt, skin, toxic, toxicity, zhongying wang

Ingesting silver — in antimicrobial health tonics or for extensive medical treatments involving silver — can cause argyria, condition in which the skin turns grayish-blue. Brown researchers have discovered how that happens. The process is similar to developing black-and-white photographs, and it’s not just the silver.

PROVIDENCE, R.I. [Brown University] — Researchers from Brown University have shown for the first time how ingesting too much silver can cause argyria, a rare condition in which patients’ skin turns a striking shade of grayish blue.

“It’s the first conceptual model giving the whole picture of how one develops this condition,” said Robert Hurt, professor of engineering at Brown and part of the research team. “What’s interesting here is that the particles someone ingests aren’t the particles that ultimately cause the disorder.” (more…)

Another Advance on the Road to Spintronics

By Guest PostOctober 21, 2012Sciencealbert einstein, alexander gray, analyzer, basis, berkeley lab, charles fadley, computing industry, contamination, data, dilute, electron, electronic structure, energy conversion, energy-efficient, exchange model, facility, ferromagnetic, gallium arsenide, gallium atom, gamnas, harpes, hyogo, jan minar, Japan, jun fujii, kelvin, magnetic atom, magnetic semiconductor, memory architecture, nanoscale device, new technique, p d, peter stone, photoelectric effect, photoemission, photovoltaic cell, processing, room temperature, shigenori ueda, spin, spintronic application, spintronic technology, spring8, storage, surface reaction, synchrotron radiation, xray angle, yoshiyuki yamashita

Berkeley Lab Researchers Unlock Ferromagnetic Secrets of Promising Materials

Spintronic technology, in which data is processed on the basis of electron “spin” rather than charge, promises to revolutionize the computing industry with smaller, faster and more energy efficient data storage and processing. Materials drawing a lot of attention for spintronic applications are dilute magnetic semiconductors – normal semiconductors to which a small amount of magnetic atoms is added to make them ferromagnetic. Understanding the source of ferromagnetism in dilute magnetic semiconductors has been a major road-block impeding their further development and use in spintronics. Now a significant step to removing this road-block has been taken.

A multi-institutional collaboration of researchers led by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), using a new technique called HARPES, for Hard x-ray Angle-Resolved PhotoEmission Spectroscopy, has investigated the bulk electronic structure of the prototypical dilute magnetic semiconductor gallium manganese arsenide. Their findings show that the material’s ferromagnetism arises from both of the two different mechanisms that have been proposed to explain it. (more…)

Freezing Electrons in Flight

By Guest PostOctober 13, 2012Science1878, arizona, artificial, arvinder sandhu, atmosphere, atom, attosecond, camera, chemical process, destruction, eadweard muybridge, earth, electron, electron emission, electronic devices, electronic motion, emulsion plate, excited atom, femtosecond, formation, ground, henry timmers, high energy, horse, iconic series, laser flash, laser pulses, microscopic dynamics, molecular process, muybridge, mystery, natural, niranjan shivaram, oxygen molecule, ozone, phenomena, photo, photograph, physical, quintillionths, real-time, second, stroboscopy, super excited, technique, touch, ultrafast, ultraviolet light, university, upper atmosphere, zeptosecond

Using the world’s fastest laser pulses, which can freeze the ultrafast motion of electrons and atoms, UA physicists have caught the action of molecules breaking apart and electrons getting knocked out of atoms. Their research helps us better understand molecular processes and ultimately be able to control them in many possible applications.

In 1878, a now iconic series of photographs instantly solved a long-standing mystery: Does a galloping horse touch the ground at all times? (It doesn’t.) The images of Eadweard Muybridge taken alongside a racetrack marked the beginning of high-speed photography.

Approximately 134 years later, researchers in the University of Arizona department of physics have solved a similar mystery, one in which super-excited oxygen molecules have replaced the horse, and ultrafast, high-energy laser flashes have replaced Muybridge’s photo emulsion plates. (more…)

First Stars, Galaxies Formed more Rapidly than Expected

By Guest PostSeptember 9, 2012Scienceanalysis, anisotropy probe, Antarctica, astronomer, background, Berkeley, california, christian reichardt, cmb, cosmic microwave, cosmological evolution, data, earth axis, electron, Epoch, Galaxy, geographic, herschel satellite, high resolution, hydrogen atom, image, john carlstrom, kavli foundation, microwave, millimeter wavelength, national, neutral, neutral gas, oliver zahn, period, plasma, polar plateau, proton, radiation, reionization, s chandrasekhar, science foundation, south pole, star, telescope, ultraviolet light, universe, university, wilkinson

Analysis of data from the National Science Foundation’s South Pole Telescope, for the first time, more precisely defines the period of cosmological evolution when the first stars and galaxies formed and gradually illuminated the universe. The data indicate that this period, called the epoch of reionization, was shorter than theorists speculated — and that it ended early.

“We find that the epoch of reionization lasted less than 500 million years and began when the universe was at least 250 million years old,” said Oliver Zahn, a postdoctoral fellow at the Berkeley Center for Cosmological Physics at the University of California, Berkeley, who led the study. “Before this measurement, scientists believed that reionization lasted 750 million years or longer, and had no evidence as to when reionization began.” (more…)

A Direct Look at Graphene

By Guest PostAugust 5, 2012Scienceandrey shytov, atom, berkeley lab, carbon atom, coulomb potential, dirac quasiparticles, electrical conductor, electron, factor, graphene, graphene device, graphene properties, hexagonally patterned, honeycomb, lattice, michael crommie, paul dirac, speed of light, stm, victor brar, yang wang

Direct Imaging by Berkeley Lab Researchers Confirms the Importance of Electron-Electron Interactions in Graphene

Perhaps no other material is generating as much excitement in the electronics world as graphene, sheets of pure carbon just one atom thick through which electrons can race at nearly the speed of light – 100 times faster than they move through silicon. Superthin, superstrong, superflexible and superfast as an electrical conductor, graphene has been touted as a potential wonder material for a host of electronic applications, starting with ultrafast transistors. For the vast potential of graphene to be fully realized, however, scientists must first learn more about what makes graphene so super. The latest step in this direction has been taken by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley.

Michael Crommie, a physicist who holds joint appointments with Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Physics Department, led a study in which the first direct observations at microscopic lengths were recorded of how electrons and holes respond to a charged impurity – a single Coulomb potential – placed on a gated graphene device. The results provide experimental support to the theory that interactions between electrons are critical to graphene’s extraordinary properties. (more…)

The Weird World of “Remote Heating”

By Guest PostApril 10, 2012Scienceatom, bounce, carbon nanotube, electric current, electron, john cumings, joule heating, kamal baloch, metal wire, nanoelectronic, nanometer, nanoscale, nature nanotechnology, object, phenomenon, university of maryland

*UMD Researchers Discover Nanoscale Phenomena with Potential for Computer Speed Advances*

College Park, Md.– A team of University of Maryland scientists have discovered that when electric current is run through carbon nanotubes, objects nearby heat up while the nanotubes themselves stay cool, like a toaster that burns bread without getting hot. Understanding this completely unexpected new phenomenon could lead to new ways of building computer processors that can run at higher speeds without overheating.

“This is a new phenomenon we’re observing, exclusively at the nanoscale, and it is completely contrary to our intuition and knowledge of Joule heating at larger scales-for example, in things like your toaster,” says first author Kamal Baloch, who conducted the research while a graduate student at the University of Maryland. “The nanotube’s electrons are bouncing off of something, but not its atoms. Somehow, the atoms of the neighboring materials-the silicon nitride substrate-are vibrating and getting hot instead.” (more…)