Molecular abacus counts on buckyballs.One of the world's oldest counting machines is now also one of the newest. Scientists at the IBM (International Business Machines Corporation, Armonk, NY, www.ibm.com) The world's largest computer company. IBM's product lines include the S/390 mainframes (zSeries), AS/400 midrange business systems (iSeries), RS/6000 workstations and servers (pSeries), Intel-based servers (xSeries) Zurich Research Laboratory have constructed a tiny abacus that substitutes carbon-60 buckyballs for the traditional beads. This nanoscale abacus is the first room-temperature device that can store and manipulate numbers at the molecular level. The buckyballs rest in orderly rows along shallow steps cut into a piece of copper. The tip of a scanning tunneling microscope scanning tunneling microscope, device for studying and imaging individual atoms on the surfaces of materials. The instrument was invented in the early 1980s by Gerd Binnig and Heinrich Rohrer, who were awarded the 1986 Nobel prize in physics for their work. (STM (Scanning Tunneling Microscope) A microscope that can image down to the atomic level. An STM uses a piezoelectric tube with a tiny sharp tip at the end that is moved within nanometers of the object being sampled. ) pushes the molecules along the steps, just as a person's finger would slide the beads of an abacus back and forth on a wire. Some of the underlying copper atoms move too, form- ing tiny "kinks" that fix the buckyballs in their new positions. The scientists report their achievement in the Nov. 11 Applied Physics Letters Applied Physics Letters is a weekly peer-reviewed scientific journal published by the American Institute of Physics devoted to the publication of new experimental and theoretical papers about applications of physics to science, engineering, and modern technology. . The inspiration to make a nanoscale abacus came not only from previous work that moved single atoms with an STM, but also from a trip to Japan, says pro- ject leader James K. Gimzewski. "I saw that in the Tokyo railway station, many of the ticket sellers actually use abacuses." From that observation, Gimzewski and his group decided to "start from the bottom up and make a working demo of an abacus, using single molecules." Right now, only one buckyball buckyball, colloquial term for buckminsterfullerene, a roughly spherical fullerene molecule consisting of 60 carbon atoms. Buckytube is a generic term for cylindrical fullerenes. can be moved at a time, a process Gimzewski des- cribes as "moving grains of sand with Mount Fuji." Faster STM tips and designs with many probes working in parallel could improve the speed of the device. |
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