- Number 390 |
- June 10, 2013
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Atom by atom, bond by bond, a chemical reaction caught in the act
Graphene nanostructures can form the transistors, logic gates, and other elements of exquisitely tiny electronic devices, but to become practical they will have to be mass produced with atomic precision. Hit-or-miss, top-down techniques, such as unzipping carbon nanotubes, can’t do the job. When Felix Fischer of DOE’s Lawrence Berkeley National Laboratory set out to develop graphene nanostructures from the bottom up, using controlled chemical reactions, the outcomes of the reaction were unexpected, but the visual evidence was even more so.
Fischer, a staff scientist in Berkeley Lab’s Materials Sciences Division (MSD) and a professor of chemistry at the University of California at Berkeley, worked with his colleague Michael Crommie of MSD, a UC Berkeley professor of physics. To see what was happening at the single-atom level they used a uniquely sensitive noncontact atomic force microscope (nc-AFM) to image the starting molecule – composed of three benzene rings linked by carbon atoms – placed on a silver surface. Heating the substrate induced reactions, and the microscope recorded the products. -
French nuclear designers tap American expertise
The world's nuclear experts have reached out to U.S. Department of Energy engineers for help evaluating a new nuclear reactor design that could increase safety margins while reducing waste.
The project marked a series of firsts for nuclear engineers on both sides of the Atlantic. They fostered a new collaboration and tapped state-of-the-art analysis tools to evaluate a first-of-a-kind reactor design.
France's Atomic Energy and Alternative Energies Commission (CEA) collaborated with nuclear engineers at DOE's Idaho National Laboratory and Argonne National Laboratory for the project. Its goal: assess safety and performance parameters for a new fast reactor design. -
Tiny crystals glow bright in LED lights
Minuscule crystals that glow different colors may be the missing ingredient for white LED lighting that illuminates homes and offices as effectively as natural sunlight.
Light-emitting diodes, better known as LEDs, offer substantial energy savings over incandescent and fluorescent lights and are easily produced in single colors such as red or green commonly used in traffic lights or children's toys.
Developing an LED that emits a broad spectrum of warm white light on par with sunlight has proven tricky, however. LEDs, which produce light by passing electrons through a semiconductor material, often are coupled with materials called phosphors that glow when excited by radiation from the LED.
"But it's hard to get one phosphor that makes the broad range of colors needed to replicate the sun," said John Budai, a scientist in ORNL's Materials Science and Technology Division. "One approach to generating warm-white light is to hit a mixture of phosphors with ultraviolet radiation from an LED to stimulate many colors needed for white light." -
Looking for the Higgs boson’s big brother
Last year, experiments at the Large Hadron Collider discovered a new particle that seemed to fit the description of the long-sought Higgs boson. Since then scientists have investigated the particle’s properties in greater detail, and so far all tests confirm that this is the Higgs boson predicted by the theoretical framework known as the Standard Model. More than 1,800 scientists, engineers and graduate students from U.S. institutions collaborate on the LHC experiments.
Even if the new particle gives mass to elementary particles such as electrons and quarks, it may not be acting alone. Nothing forbids the existence of multiple Higgs bosons. Scientists working on the CMS experiment recently published the results of their search for a heavier Higgs particle.
