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Surprising Control over Photoelectrons from a Topological Insulator: Berkeley Lab scientists discover how a photon beam can flip the spin polarization of electrons emitted from an exciting new material

Plain-looking but inherently strange crystalline materials called 3D topological insulators (TIs) are all the rage in materials science. Even at room temperature, a single chunk of TI is a good insulator in the bulk, yet behaves like a metal on its surface.

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The interior bulk of a topological insulator is indeed an insulator, but electrons (spheres) move swiftly on the surface as if through a metal. They are spin-polarized, however, with their momenta (directional ribbons) and spins (arrows) locked together. Berkeley Lab researchers have discovered that the spin polarization of photoelectrons (arrowed sphere at upper right) emitted when the material is struck with high-energy photons (blue-green waves from left) is completely determined by the polarization of this incident light.

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Long Predicted Atomic Collapse State Observed in Graphene: Berkeley Lab researchers recreate elusive phenomenon with artificial nuclei

The first experimental observation of a quantum mechanical phenomenon that was predicted nearly 70 years ago holds important implications for the future of graphene-based electronic devices.

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An artificial atomic nucleus made up of five charged calcium dimers is centered in an atomic-collapse electron cloud.

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NASA Rover Finds Conditions Once Suited for Ancient Life on Mars

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Two Different Aqueous Environments
This set of images compares rocks seen by NASA's Opportunity rover and Curiosity rover at two different parts of Mars. On the left is " Wopmay" rock, in Endurance Crater, Meridiani Planum, as studied by the Opportunity rover.

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NASA Pinpoints Causes of 2011 Arctic Ozone Hole

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Maps of ozone concentrations over the Arctic come from the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite. The left image shows March 19, 2010, and the right shows the same date in 2011. March 2010 had relatively high ozone, while March 2011 has low levels.

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Herschel gets to the bottom of black-hole jets

Astronomers using ESA's Herschel space observatory have detected emission from the base of black-hole jets for the first time. While studying the black-hole binary system GX 339-4 in a multi-wavelength observation campaign, they noticed changes in the source's X-ray and radio emissions signalling the onset of powerful jets being released from the black hole's vicinity. This prompted the astronomers to observe the source at far-infrared wavelengths with Herschel. As the first observation of emission from jets in a black-hole binary system at these wavelengths, the data have allowed the astronomers to probe the jets down to their base, where the far-infrared emission originates. Herschel's contribution to the multi-wavelength observations has proved a crucial addition to the understanding of black-hole jets and of the physical processes that take place very close to a black hole.

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Artist's impression of the GX 339-4 black-hole binary system.

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Breaking the final barrier: room-temperature electrically powered nanolasers

Electrically powered nano-scale lasers have been able to operate effectively only in cold temperatures. Researchers in the field have been striving to enable them to perform reliably at room temperature, a step that would pave the way for their use in a variety of practical applications.

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The illustration on the left shows the variations of light intensity within a nanolaser. The figure on the right shows schematically a nanolaser with a metallic cavity, where the center red region confines electrons and the grey enclosure is a silver cavity. The blue layer on top is a substrate where the laser structure is grown. The orange-yellow color on top indicates the light emission. Research led by Arizona state University engineering professor Cun-Zheng Ning has produced nanolasers that can operate under a battery power at room temperatures – instead of only in refrigerated conditions – which opens the door to use of the lasers in many practical applications in modern electronics.

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High-performance, NW-OPTs open the way for optoelectronic device miniaturization

Research team of Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea, developed high-performance organic phototransistors (OPTs) based on single-crystalline n-channel organic nanowires.

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Schematic diagram of single-crystalline nanowire organic phototransistors

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Blue Bursts of Hot Young Stars Captured by Hubble

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Temp-controlled 'nanopores' may allow detailed blood analysis

Tiny biomolecular chambers called nanopores that can be selectively heated may help doctors diagnose disease more effectively if recent research by a team at the National Institute of Standards and Technology (NIST), Wheaton College, and Virginia Commonwealth University (VCU) proves effective. Though the findings* may be years away from application in the clinic, they may one day improve doctors' ability to search the bloodstream quickly for indicators of disease—a longstanding goal of medical research.

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By tethering gold nanoparticles (large spheres in top image) to the nanopore (violet), the temperature around the nanopore can be changed quickly and precisely with laser light, allowing scientists to distinguish between similar molecules in the pore that behave differently under varied temperature conditions.

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University of Illinois researchers develop novel technique for chemical identification at the nanometer scale

For more than 20 years, researchers have been using atomic force microscopy (AFM) to measure and characterize materials at the nanometer scale. However AFM-based measurements of chemistry and chemical properties of materials were generally not possible, until now.

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Atomic force microscope infrared spectroscopy (AFM-IR) of polymer nanostructures.

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