Mechanosynthesis with AFM as a step toward advanced nanotechnology

Mechanosynthesis with AFM as a step toward advanced nanotechnology

Robert A. Freitas Jr. brings to our attention a major step on the road to advanced nanotech, published a couple weeks ago in Science (abstract). He writes:

This paper reports purely mechanical-based covalent bond-making and bond-breaking (true mechanosynthesis) involving atom by atom substitution of silicon (Si) atoms for tin (Sn) atoms in an Sn monolayer surface on a Si(111) surface; also demonstrates atomically precise exchange of lead (Pb) and indium (In) on Si(111) surface. This is the first report of a complex pattern being drawn on a 2D surface, literally atom by atom, purely via mechanical forces.

Working on a single atomic layer of tin atoms grown on a single-crystal silicon surface, the Japanese-European collaboration maneuvered an atomic force microscope (AFM) tip precisely (plus or minus 0.01 nm) over a single silicon atom defect in the tin surface, and were able to reversibly exchange a tin atom on the apex of the tip and the silicon atom on the surface. These experiments were done at room temperature and, unlike earlier demonstrations in which a scanning tunneling microscope (STM) tip was used to interchange atoms weakly bond to a metallic surface through use of an electrical bias, this demonstration used mechanical force to interchange strongly bound atoms.

To characterize what was happening between the atoms involved, the researchers did a first principles quantum mechanics simulation of the tip-surface interactions. The simulations show that the key step happens when the outermost atom of the tip and the target atom on the surface have an equal number of bonds with the surrounding atoms so that they lose the property of being part of the tip or the surface.

The method used here of vertical interchange of atoms between tip and surface was found to be about ten times faster than previous lateral manipulations of atoms with the AFM. Using vertical manipulation as an atomic pen, the authors wrote the chemical symbol for silicon (Si) with 12 silicon atoms on the tin surface. In supplementary material, the authors report doing similar manipulations with lead and indium atoms on a silicon surface. They propose that:

This manipulation technique may pave the way toward selective semiconductor doping, practical implementation of quantum computing, or atomic-based spintronics. The possibility of combining sophisticated vertical and lateral atom manipulations with the capability of AFM for single-atom chemical identification may bring closer the advent of future atomic-level applications, even at room temperature.


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  1. kurt9 November 6, 2008 at 1:34 pm - Reply

    The significance of this is that it was done at room temperature.

  2. JamesG November 7, 2008 at 6:49 am - Reply

    Somebody needs to build or use a currently built supercomputer, to design and simulate a complete nanobot. Once that happens, people will pull out all stops in the quest to make nanorobotics. I don’t understand why people move so slow on this, I can’t think of anything more important than curing aging/disease/hunger/poverty which nanorobotics would do.

  3. the oakster1 November 10, 2008 at 3:34 pm - Reply

    Ever here of Darwin, Galileo, Hypatia, the Greeks, the dark ages? It’s called anti-science; more would be the dragging of America’s feet from settling outer space, stem cells.

    And, it seems you and CRN folk think social issues are so simple! You all think that being fed is the end all of humanity. Once you save all these people, they are going to express their anti-science in ways you would not believe! Do you really think they are going to just drop their religion? Their goal is to die and go to heaven and join Jesus Christ!

    By all means, save all these people; but, the CRN/LIefboat org plan to confine all of humanity forever just to keep humanity fed till the sun turns into a planetary nebula isn’t 1) logical, and 2) ethical. CRN talks about ‘disruptive’ technologies . . . their plans are to ‘disrupt’ humanities momentuim from getting away from the irrationalists past out into space. Hmm, I wonder why? Gee, could they be socially conditioned incrowders? Yes!

  4. the oakster1 November 10, 2008 at 3:48 pm - Reply

    I can’t believe you guys can’t get your hands on a supercomputer . . .

    All f1-racing teams have supercomputers these days; maybe we should see if they are willing to lone one!

  5. Ambiguous User November 18, 2008 at 12:11 am - Reply

    I take exception to that remark, oakster1.

    There are perfectly rational, scientifically minded, and reasonable Christians out here, who DO NOT want to bring about apocalypse, brainwash the masses, and keep humanity concerned only with Earthly issues.

    The problem is not Jesus Christ, but greed and capitalistic imprisonment. If we spent 1 billion dollars as easily on humanitarian general research (such as a super-computer aimed at simulating nano-robots, such as the kind the NanoComputer Dream Team wants to make…) as easily as we do jumping to the rescue (USA) of any country or military project that cries for help ($), many more problems would be solved (such as dependence on non-renewable resources).

    Stem cells is an ethical issue, not anti-science. The philosophy of Science (observational naturalism) does not say “do everything, and make sure it has a control, so you can measure how quick it dies without food; maybe you can learn how cells replicate that way, maybe.” Science says,” study living creatures as they are, with as little interference as possible, and form theories as to how they work.” Then, when you have those theories, you can do biotic chemistry, and act on those theories on animal cells (in-vertebrate animals, for instance).

    Give us a super-computer! Decentralized or no, we want to simulate nanites!

    The Raving Masses (not otherwise known as “anti-scientists.”)

    Ambiguous User

  6. […] The researchers note that even with this impressive progress, a “millipede” type memory might not be competitive with flash memory. Regardless, the techniques for rapid and precise control of arrays of AFM tips might be of use to proposals for mechanosynthesis with AFM (see this post from two weeks ago and this one from three weeks ago).—Jim […]

  7. Aanya Shaw July 8, 2011 at 8:27 am - Reply

    @kurt9 — you hit the nail … most people never realize how important it is for any experiment to be feasible at room temperature.

    @JamesG — I am sure efforts are on, but it’s not easy to get the stuff done. As Mr. Ambiguous points out … the capitalistic society also plays a deep role in it. It’s crazy how big companies can actually stay away from progressive research to make sure that they are ROI positive on their last research project

    Aanya Shaw
    Visit Us At: Jura Capresso Impressa Z5

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