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Toulouse, France

Ohmann R.,TU Dresden | Ohmann R.,Okinawa Institute of Science and Technology | Meyer J.,TU Dresden | Nickel A.,TU Dresden | And 6 more authors.
ACS Nano

A supramolecular nanostructure composed of four 4-acetylbiphenyl molecules and self-assembled on Au (111) was loaded with single Au adatoms and studied by scanning tunneling microscopy at low temperature. By applying voltage pulses to the supramolecular structure, the loaded Au atoms can be rotated and translated in a controlled manner. The manipulation of the gold adatoms is driven neither by mechanical interaction nor by direct electronic excitation. At the electronic resonance and driven by the tunneling current intensity, the supramolecular nanostructure performs a small amount of work of about 8 × 10-21 J, while transporting the single Au atom from one adsorption site to the next. Using the measured average excitation time necessary to induce the movement, we determine the mechanical motive power of the device, yielding about 3 × 10-21 W. (Figure Presented). © 2015 American Chemical Society. Source

Perera U.G.E.,Ohio University | Ample F.,Agency for Science, Technology and Research Singapore | Kersell H.,Ohio University | Zhang Y.,Ohio University | And 8 more authors.
Nature Nanotechnology

The design of artificial molecular machines1-19 often takes inspiration from macroscopic machines13-19. However, the parallels between the two systems are often only superficial, because most molecular machines are governed by quantum processes. Previously, rotary molecular motors3 powered by light4-6 and chemical7-11 energy have been developed. In electrically driven motors, tunnelling electrons from the tip of a scanning tunnelling microscope have been used to drive the rotation of a simple rotor12 in a single direction and to move a fourwheeled molecule across a surface13. Here, we show that a stand-alone molecular motor adsorbed on a gold surface can be made to rotate in a clockwise or anticlockwise direction by selective inelastic electron tunnelling through different subunits of the motor. Our motor is composed of a tripodal stator for vertical positioning, a five-arm rotor for controlled rotations, and a ruthenium atomic ball bearing connecting the static and rotational parts. The directional rotation arises from sawtooth-like rotational potentials, which are solely determined by the internal molecular structure and are independent of the surface adsorption site. © 2013 Macmillan Publishers Limited. All rights reserved. Source

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