To drive or not to drive a simple question of orientation
And this is what Ernst and Parschau observed: after ten STM stimulations, the molecule had moved six nanometres forwards in a more or less straight line. "The deviations from the predicted trajectory result from the fact that it is not at all a trivial matter to stimulate all four motor units at the same time", explains "test driver" Ernst.
Another experiment showed that the molecule really does behave as predicted. A part of the molecule can rotate freely around the central axis, a C-C single bond the chassis of the car, so to speak. It can therefore "land" on the copper surface in two different orientations: in the right one, in which all four wheels turn in the same direction, and in the wrong one, in which the rear axle wheels turn forwards but the front ones turn backwards upon excitation the car remains at a standstill. Ernst und Parschau were able to observe this, too, with the STM.
Therefore, the researchers have achieved their first objective, a "proof of concept", i.e. they have been able to demonstrate that individual molecules can absorb external electrical energy and transform it into targeted motion. The next step envisioned by Ernst and his colleagues is to d
|Contact: Prof. Dr. Karl-Heinz Ernst, Empa Nanoscale Materials Science|
Swiss Federal Laboratories for Materials Science and Technology (EMPA)