2 June 2009

Tiny rotors could build nano generators

In a move that may help the development of future rotor-based machinery at the nanoscale level, there is now a plan underway to understand the rotation of molecules on a fixed surface.

The research focused on rotating magnetic fields, which play an important part in machines like electric motors and generators. The difficulty for technology at the atomic scale is to replicate this property with rotors the size of small molecules. Researchers already identified a number of rotating molecules, but so far they have not used molecules to create rotating magnetic fields.

Researchers used a gold metal surface to anchor phtalocyanine molecules, which have a metallic center, in a large array. The anchor point, a single gold atom on top of the gold surface attached to a nitrogen atom of the molecule, allowed the molecules to rotate just off-center.

“The difficulty in creating molecular rotors is that molecules need a fixed anchor point and will often react with the surface you want to fix them to,” said Professor Werner Hofer, from the Chinese Academy of Sciences in Beijing School of Chemistry. “A gold surface interacts very weakly with molecules; it moreover provides regular anchor points to attach single molecules, which then line up in large and well ordered arrays.”

“The center atoms, which are metallic, spin around the gold atoms creating an off-axis rotation. The beauty of phtalocyanines is that the center can be functionalized with any metal atom; the research could then lead to the development of rotating magnetic fields at a very small scale.”

The researchers said this could be the first step toward the fabrication of machines for the generation of currents at small scale.

For related information, go to www.isa.org/manufacturing_automation.