nano-scale

Scientists are working on infinitesimally small rotors that may one day lead to nano-scale generators.
Collaborating with the Chinese Academy of Sciences in Beijing, a research team have already probed the rotation of molecules on a fixed surface to understand how they may help in the development of future rotor-based machinery at nanoscale level.he researchers focussed on rotating magnetic fields, which play an important part in machines like electric motors and generators.
However, the biggest difficulty for technology at the atomic scale is to replicate this property with rotors the size of small molecules.
Already, scientists have identified a number of rotating molecules, but until now they haven't been successful in using molecules to create rotating magnetic fields.
They used a gold metal surface to anchor phtalocyanine molecules, which have a metallic centre, in a large array and created an anchor point-a single gold atom on top of the gold surface attached to a nitrogen atom of the molecule-that allowed the molecules to rotate just off-centre.
"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. 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," said professor Werner Hofer, from the University's School of Chemistry.
He added: "The centre atoms, which are metallic, spin around the gold atoms creating an off-axis rotation. The beauty of phtalocyanines is that the centre can be functionalised with any metal atom; the research could then lead to the development of rotating magnetic fields at a very small scale."
According to scientists, this could be the first step towards the fabrication of machines for the generation of currents at small scale.