Researchers construct the world's smallest electric motor

New nanorotor consists of only one molecule

The molecular motor sits with its sulfur atom (yellow) on the copper surface, the two "arms" of hydrocarbons rotate, influenced by electrons from the microscope tip (gray). © Heather L. Tierney, Colin J. Murphy, April D. Jewell, Ashleigh E. Baber, Erin V. Iski, Harout Y. Khodaverdian, Allister F. McGuire, Nikolai Klebanov and E. Charles H. Sykes
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American chemists have succeeded in constructing the world's smallest electrically controllable motor: a molecule just one nanometer in size. The tiny component is thus 60, 000 times smaller than the diameter of a human hair and 200 times smaller than the smallest known nanomotors. As the scientists in the journal "Nature Nanotechnology" report, this is the first time that a construct of this size is powered by electric current.

"There has been much progress in the construction of molecular motors driven by light or chemical reactions, " says study leader E. Charles H. Sykes of Tufts University in Medford, Massachusetts. "We've now shown that using a single electric current can make a single molecule do something non-random, directional."

The nanomotor consists of an asymmetric molecule that rotatably rests on a copper surface. With electrons released from the tip of a scanning tunneling microscope, the researchers were able to specifically influence the rotational speed and direction of rotation of this molecule.

Soon new class of nano-components?

According to the principle of this engine, a completely new class of nanodevices could be created in the future, the researchers predict. "Coupling molecular motion with electrical signals could be used to construct miniature gears in nano-circuits, " says Sykes. Such Nanozahnräder could be used for example in future phones. Even tiny rotary pumps, for example, in medical nanodevices are conceivable, the researchers believe.

However, the nanomotor can only be controlled at extremely low temperatures of about minus 260 degrees Celsius. At higher temperatures, he still turns too fast. You have to get that under control, say the researchers. Next, you want to first register the molecular motor in the Guinness Book of Records. display

Rotatable arms made of hydrocarbon

The basis of the new nanomotor is formed by a molecule of sulfur, carbon and hydrogen atoms, the so-called butyl-methyl-sulfide. Two different lengths of hydrocarbon compounds originate from one central sulfur atom. When researchers put such a molecule on a copper surface, the central sulfur atom combined with the copper. The rmchen remained free and rotated around the middle of the molecule.

The scientists placed this setup in a scanning tunneling microscope. In this microscope, an ultrafine tip scans the surface of materials with the help of an electron current. The electrons skip the tiny distance between the tip and the material.

Under vacuum and at temperatures near absolute zero, the chemists succeeded in influencing the molecule with the aid of this so-called tunneling current. Instead of spinning unordered in all directions, now more rotation has taken place in only one direction, the researchers report. In the case of a mirrored molecule, instead of the direction, the speed of rotation through the tunneling current could be increased. (Nature Nanotechnology, 2011; DOI: 10.1038 / nnano.2011.142)

(Nature Nanotechnology / Tufts University / dapd, 05.09.2011 - NPO)