Pinpoint splitting of molecules.The sharp tip of a scanning tunneling microscope's needlelike probe has proved a versatile tool for mapping a surface's microscopic ridges and hollows and for moving small clumps clump n. 1. A clustered mass; a lump: clumps of soil. 2. A thick grouping, as of trees or bushes. 3. A heavy dull sound; a thud. v. of atoms from place to place. Scientists can also uses this instrument to split up individual molecules lying on such surface. Phaedon Avouris of 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) Thomas J. Watson Research Center The Thomas J. Watson Research Center is the headquarters for the IBM Research Division. The center is on three sites, with the main laboratory in Yorktown Heights, New York, 45 miles north of New York City, a building in Hawthorne, New York, and offices in Cambridge, in Yorktown Heights, N.Y., and his co-workers have now demonstrated that electrons emitted from a microscope's tip can transfer sufficient energy to excite and shake apart a decaborane molecule sitting on a silicon surface. Each decaborane molecule consists of 10 boron boron (bōr`ŏn) [New Gr. from borax], chemical element; symbol B; at. no. 5; at. wt. 10.81; m.p. about 2,300°C;; sublimation point about 2,550°C;; sp. gr. 2.3 at 25°C;; valence +3. atoms and 14 hydrogen atoms. When deposited on a silicon surface and viewed with 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. , these molecules appear as rounded, elongated e·lon·gate tr. & intr.v. e·lon·gat·ed, e·lon·gat·ing, e·lon·gates To make or grow longer. adj. or elongated 1. Made longer; extended. 2. Having more length than width; slender. protrusions about 7 angstroms across. Warming up the coated silicon slab frees these molecules, and they tend to migrate to certain irregularities in the otherwise orderly arrangement of silicon atoms at the slab's surface. The molecules break apart at these defects, and boron atoms slip into the silicon structure. Instead of heating up the entire crystal to produce borondoped silicon, Avouris and his team selectively excite individual decaborane molecules to dope only small, specific regions of the silicon surface. They use a scanning tunneling microscope to locate the surface-hugging molecules. Then, by carefully readjusting the voltage applied to the microscope's tip, they send a pulse of electrons of just the right energy to excite a particular molecule, which dissociates. Avouris suggests that the same procedure could be used for controlling surface chemistry on a molecular scale in a variety of situations. |
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