Science Highlights

Highlight Archive: 2008 | 07 | 06 | 05 | 04 | 03 | 02 | 01

Creating Highly Sought Magnetic Nanoparticles in One Step
Researchers from the University of Minnesota have demonstrated a one-step technique for producing a class of magnetic nanoparticles that could be used in everything from biomedical applications to data storage. Consisting of an iron and cobalt core with a gold shell, the nanoparticle’s unique, and potentially very useful, magnetic properties were characterized at the NSLS.

Probing Orientational Order of Liquid Crystals
Orientational order enables technological applications for liquid crystals as positional order does for crystals. Electric-field-induced reorientation of the large optical anisotropy of the molecules has been utilized in applications from high-resolution camera viewfinders to large-area monitors. In order to learn more about the behavior of these intriguing and technologically important phases three groups collaborated with NSLS scientists to use the technique of resonant x-ray scattering for measuring orientational order in layered liquid crystal phases with periodicities from nanometers to micrometers.

Investigating Plutonium Oxidation State Transformations
Plutonium is an element of concern in disposal and remediation scenarios because of its radiotoxicity and very long half-lives for several isotopes. Once released into the environment, the movement of Pu is strongly related to its oxidation state. In aqueous solutions, Pu can exist in oxidation states III, IV, V, and VI, with two or three of these oxidation states commonly present at equilibrium. Pu(V) and Pu(VI) are typically two orders of magnitude more mobile than Pu(III) or Pu(IV). To further investigate Pu oxidation state transformations in its natural environment, a team of researchers used x-ray techniques at the NSLS.

Spreading and Surface Freezing of Nanometer-Thick Oil Films on Water
Most kindergarteners can tell you that no matter how hard you try to mix them, a droplet of oil won't spread on water. However, things are different in the nano world. Recently, a team of researchers from Durham and Oxford universities in the United Kingdom, Bar-Ilan University in Israel, and BNL used x-ray experiments at the NSLS to show that a nanometer-thick layer of oil can be induced to spread on the surface of water by a minute amount of an additive called a surfactant. More intriguing, these layers exhibit a very peculiar behavior known as the "surface freezing effect."

DNA Technique Yields 3-D Crystalline Organization of Nanoparticles
In an achievement some see as the "holy grail" of nanoscience, Brookhaven researchers have for the first time used DNA to guide the creation of three-dimensional, ordered, crystalline structures of nanoparticles (particles with dimensions measured in billionths of a meter). The ability to engineer such 3-D structures is essential to producing functional materials that take advantage of the unique properties that may exist at the nanoscale – for example, enhanced magnetism, improved catalytic activity, or new optical properties. The research was published in the January 31, 2008, issue of the journal Nature.

Efficiency Doubling in a Laser-Seeded Free Electron Laser Amplifier
As scientific research continues to explore the limits of smaller (nanometer and sub nanometer) and faster (femtosecond and attosecond) phenomena, light pulses are commonly used as probing tools. Free electron lasers (FELs) are capable of generating light levels that exceed those of conventional synchrotron sources by many orders of magnitude. But by simply relying on the FEL instability, x-ray FEL emission can have good transverse (spatial) coherence, but lacks longitudinal (temporal) coherence. A proposed solution is seeded FEL emission, in which the instability is initiated by a coherent seed laser pulse. The NSLS Source Development Laboratory detuning experiment has demonstrated the doubling of the FEL efficiency without degradation of its quality. This is the first direct experimental demonstration of the FEL spectral stability in a laser-seeded FEL.