Category: Nanoscale Bulk Technologies

from the fine-focus dept.
An item on the Nature Science Update website tells of researchers at the Ludwig-Maximilians University in Munich, who have found a way to focus, reflect and split an atom laser beam. They were able to generate a coherent atom beam from a Bose-Einstein condensate. Magnetic forces are used to hold the condensate in a trap. A beam of coherent atoms can be formed by letting the condensate stream out through an opening in the trap's walls.
The German researchers produced an atom laser beam of rubidium-87 atoms. They used normal lasers to tune the atoms' magnetic behavior, then used magnets as mirrors to reflect the atom laser beam and to store it. The paper describing their work appeared in Physical Review Letters, 87: 123 – 321 (2001).

from the cold-current- dept.
United Press International reports researchers in Hong Kong have created one-dimensional, single-walled carbon nanotubes that posses superconducting traits, adding to their potential to become the basis of a new generation of ultra-tiny electronics. Z.K. Tang and Ping Sheng, physicists at the Institute of Nanoscience and Technology at Hong Kong University of Science and Technology, led a research team that showed single isolated nanotubes can be superconductive. Furthermore, the tubes were one-dimensional. They report on the discovery in 29 June 2001 issue of Nature.
"The isolated, highly aligned and very small diameter — around four angstroms or about the width of four atoms — nanotubes demonstrate a transition to superconducting behavior around 15 degrees Kelvin, a much higher temperature than for superconductivity observed in nanotube bundles," according to a summary of the research.

from the non-carbon dept.
An extensive article in Chemical and Engineering News ("From Membranes to Nanotubules", by A. Maureen Rouhi, 11 June 2001) describes work with gold template-synthesized nanotubule membranes that are enabling new approaches to separations and analytical sensing. Researchers led by Charles R. Martin, a chemistry professor at the University of Florida, are creating membranes composed of gold nanotubules, and are working to interface the nanotubule membrane architecture with biological recognition agents for applications in chemical separations and single-molecule sensing.

A research team at the University of California at Berkeley has created nanoscale lasers from pure crystals of zinc oxide. The crystals are grown from hot zinc oxide gas using a gold catalyst on sapphire. The process forms regularly spaced nanocrystals, which in turns spurred the growth of pure zinc oxide wires measuring only 20 to 150 nanometers in diameter. The lasers emit blue and ultraviolet light, and operate at room temperature. The team reports its development in the June 8 issue of Science. Additional information is available in this report from United Press International.

from the in-a-spin dept.
Both vik and Brian Wang noted the news that Researchers at St. Andrews University in Scotland have developed a technique using specialized lasers to spin microscopic objects, such as chromosomes, without making physical contact. They report that they have used infrared lasers to spin tiny glass spheres, a glass rod and even the chromosome from a hamster. The light pulls the objects around at speeds up to five revolutions a second, but is gentle enough not to damage delicate molecules. The work is a variation of the "optical tweezers" technique: as a beam of light bends around an object, the light exerts a force on it. At the microscopic level, the force of laser light bending around tiny objects is strong enough to trap them. By moving the beam, the trapped objects move as well, allowing optical tweezers to push and pull microscopic objects. In the new research, the researchers combine the light of two lasers to create a spiral interference pattern, a pinwheel-like pattern of bright and dark spots. Changing the optical path length causes this pattern, and thus the trapped objects, to rotate.

Brian Wang also noted "My observation is that this combined with Arryx (http://www.arryx.com/overview.html) Holographic Optical Trap ("HOT") technology for splitting one laser into thousands of manipulated lasers might scale into a massive photonic assembly system at the microscopic level."

The research report appeared in the 4 May 2001 issue of Science. Additional coverage can be found on the New York Times website.