Tagged: SLAC SIMES Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 11:14 am on July 20, 2012 Permalink | Reply
    Tags: , , , , SLAC SIMES   

    From SLAC Today: “Phrase of the Week: Thermionic Emission” 

    July 20, 2012
    Mike Ross

    If you heat materials to a high enough temperature, some of their electrons will gain enough kinetic energy to literally boil off the surface and into the air or vacuum beyond. Since net motion of electrons constitutes an electrical current, this phenomena, called thermionic emission, is one of the seven basic methods for producing electricity.

    image
    (Image courtesy tpub.com)

    Thermionic emission is at the heart of a new approach to solar energy harvesting pioneered by Stanford Institute of Materials and Energy Sciences [SIMES] researchers that promises unprecedented efficiency by taking advantage of the improved performances of thermionic and thermal processes at high temperatures.”

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
    i1

     
  • richardmitnick 12:34 pm on May 16, 2012 Permalink | Reply
    Tags: , , , , SLAC SIMES   

    From SLAC Today: “X-ray Laser Uncovers Secrets of Complex Oxide Material” 

    May 16, 2012
    Mike Ross

    “An international team of researchers has used SLAC’s Linac Coherent Light Source (LCLS) to discover never-before-seen behavior by electrons in complex materials with extraordinary properties.

    The result is an important step forward in the investigation of so-called strongly correlated materials, whose unusual qualities and futuristic applications stem from the collective behavior of their electrons. By understanding how these materials work, scientists hope to ultimately design novel materials that, for instance, conduct electricity with absolutely no resistance at room temperature, dramatically improving the performance and efficiency of energy transmission and electronic devices.

    In a report published yesterday in Nature Communications, researchers led by SLAC Chief Scientist Zhi-Xun Shen and Lawrence Berkeley National Laboratory Scientist Zahid Hussain describe experiments at the LCLS with a material called striped nickelate.

    It gets its name from the pattern of alternating stripes of enhanced charge and spin that its electrons collectively assume under certain conditions. This pattern constitutes a new quantum state, and it provides a model system that scientists can use to learn about electron correlations and their impact on the properties of materials.

    The researchers hit the material with a pulse from an infrared laser, and then used an exceedingly intense, brief flash of X-ray laser light from LCLS – just a few millionths of a billionth of a second long – to record what happened.

    The initial pulse jarred the nickelate out of its striped state. By varying the interval between the two pulses, the researchers created images that showed how the charge stripes reemerged. They were surprised to find that variations in the locations of minimum and maximum charge, controlled by a quantity called phase, persisted long after the stripes’ charge distribution returned to its original magnitude.

    ‘These phase fluctuations are very important for understanding how these materials behave,’ said Wei-Sheng Lee, a SLAC physicist and lead author on the research. ‘But until now, they have been impossible to discern directly. Being able to see this electron behavior represents a new era in materials science research.'”

    image
    This diagram shows alternating stripes of charges and spins that self-organize in a particular nickel oxide at sufficiently low temperatures. This pattern constitutes a new quantum state, and it… (Image by Wei-Sheng Lee)

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
    i1

     
  • richardmitnick 1:52 pm on March 21, 2012 Permalink | Reply
    Tags: , , , SLAC SIMES,   

    From SLAC Today: “Taking the Jitter Out of X-ray Imaging at LCLS” 

    March 21, 2012
    David Reffkin

    “Two papers published on March 19 show it’s possible to significantly correct the “jitter” in X-ray laser experiments at SLAC’s Linac Coherent Light Source (LCLS), opening up important new possibilities for seeing ultrafast, atomic-scale changes in materials.

    Jitter refers to slight variations in the time it takes for an LCLS X-ray pulse to arrive at a sample. This variation can lead to lack of clarity in the processed data, much as a photo is blurred by a fast-moving subject. In experiments that seek to understand the dynamics of electrons on very short time scales, these discrepancies can make that all but impossible.

    One major class of experiments at the LCLS uses an optical laser to “pump” a sample – by setting off a reaction within it, for example – followed by ultra-short X-ray beam pulses to ”probe” the sample’s properties. By repeating this process again and again, with slightly different time lags between the two pulses, researchers can create a highly defined record of how the properties of the target material change in response to the initial laser pulse.

    ‘Knowing the exact time between the laser and X-ray pulses allows us to not only take crisp snapshots of the electrons, atoms and molecules, but also string these images together to create movies revealing the dynamics of molecular action,’ said SLAC scientist Sebastian Schorb.”

    men
    Four researchers who worked to significantly reduce the jitter in the LCLS X-ray laser beam. From left: LCLS user Martin Beye, who at the time was a postdoctoral researcher with Helmholtz-Zentrum Berlin and SLAC’s SIMES institute; AMO instrument scientist Christoph Bostedt; SXR instrument scientist Bill Schlotter; and Sebastian Schorb, a PhD student working with the AMO. Photo by Matt Beardsley

    See the full article here.

    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science. i1

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: