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IBM Science

IBM Images a Single Molecule 169

Posted by kdawson
from the blow-it-up dept.
chrb writes "New Scientist is reporting that researchers at IBM Zurich have managed to image a single molecule in detail for the first time. In the images of a pentacene molecule, the bonds between the carbon atoms are visible as five linked rings."
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IBM Images a Single Molecule

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  • by epiphani (254981) <epiphani.dal@net> on Friday August 28, 2009 @08:47AM (#29230121)

    Good job reading the article.

    FTA:

    Thanks to specialised microscopes, we have long been able to see the beauty of single atoms. But strange though it might seem, imaging larger molecules at the same level of detail has not been possible â" atoms are robust enough to withstand existing tools, but the structures of molecules are not. Now researchers at IBM have come up with a way to do it.

    emphasis mine.

  • by Anonymous Coward on Friday August 28, 2009 @08:53AM (#29230195)

    This image isn't from an electron microscope, it uses AFM (atomic force microscopy: http://en.wikipedia.org/wiki/Atomic_force_microscope), which actually touches the molecules with its tip. In this case though, they bonded a single carbon monoxoide molecule to the AFM cantilever so that it would only interact with the oxygen atoms on the pentacene molecule. I imagine it didn't image the substrate at all because of that

  • by jschen (1249578) on Friday August 28, 2009 @08:53AM (#29230197)
    For anyone who wants the original paper, published in Science today, it may be found here [sciencemag.org]. The abstract is free.
  • by Colonel Korn (1258968) on Friday August 28, 2009 @09:09AM (#29230387)

    Single strands of synthetic polymers and DNA have been imageable for many years. I imagine many of us on slashdot have personally acquired images of these single molecules before.

  • by Anonymous Coward on Friday August 28, 2009 @09:10AM (#29230399)

    From the Science article http://www.sciencemag.org/cgi/content/full/325/5944/1110 (require subscription):

    " The asymmetry in the molecular imaging in (D) (showing a "shadow" only on the left side of the molecules) is probably caused by asymmetric adsorption geometry of the CO molecule at the tip apex. "

  • by Sorny (521429) on Friday August 28, 2009 @09:11AM (#29230403) Homepage

    You are correct. I get the chance to see AFM readouts at work (you see some really cool shit in a fab), and this is a bit higher resolution that I'm used to seeing, but the "shadow" is something you'll frequently see.

    I've never "seen" the substrate from AFM scans at work either.

  • by KraftDinner (1273626) on Friday August 28, 2009 @09:12AM (#29230427)
    It's not that the molecule itself needs to be big enough, it's the structure of it. The stuff holding it together. The stuff holding the molecule together could not withstand the instruments, but now they've developed a way to do it.
  • by Colonel Korn (1258968) on Friday August 28, 2009 @09:15AM (#29230461)

    So if the Pantacene is made of Benzene and the Benzene is C6H6, what is that gray flat smooth material that the molecules are sitting on top of in the second picture? Is this simply due to a focus so incredibly tuned that you can't see past the Pentacene molecules? I would expect that to be a field of bumps and crazy random shapes because it has to be made of some molecule or atom, right? How would they finish the slide/table/surface of that so accurately? I'm used to seeing that when you see bacteria or viruses with an electron microscope, what is in effect here that we don't see an alien landscape back-dropping these molecules? I'm not calling into question the authenticity of the image, just curious if anyone knows.

    From the paper: "In this work, we present atomically resolved AFM measurements of pentacene both on a Cu(111) substrate and on a NaCl insulating film. For atomic resolution with the AFM, it is necessary to operate in the short-range regime of forces, where chemical interactions give substantial contributions."

    This was a scanning probe microscope, and the tip of the probe was a single carbon monoxide atom. Apparently the CO didn't interact with the Cu or NaCl in such a way that it saw contrast from atom to atom, but it had a finer interaction with the atoms in the pentacene.

  • by Jim Hall (2985) on Friday August 28, 2009 @09:18AM (#29230499) Homepage

    And if anyone wants to see more images from the IBM team, they have a flickr photostream. [flickr.com] It's really impressive.

  • Atoms are mostly empty space. The photo is of the electric field caused by the electrons.

    This photo [gizmodo.com] is better. The article says it is a 20-hour time exposure. The photo was available through a Reddit story [reddit.com] yesterday.
  • by Colonel Korn (1258968) on Friday August 28, 2009 @09:21AM (#29230533)

    Sorry to reply to myself, but here's the most important reason for the lack of substrate heterogeneity in the image:

    "The AFM images (Fig. 1, C and D) were recorded in constant-height mode; that is, the tip was scanned without z feedback parallel to the surface while the frequency shift {Delta}f was being recorded (16). In this and all of the following measurements, the tip height z is always given with respect to the STM set point over the substrate."

    In school, when I ran AFM I allow feedback from the tip to adjust the height of the probe so that it maintains contact with the thing I'm imaging, regardless of topography. Here, they had a very smooth substrate and then set the height of their probe to a fixed position above it.

  • Re:What the hell... (Score:4, Informative)

    by Jack Malmostoso (899729) on Friday August 28, 2009 @09:38AM (#29230751)
    The marking in Hz is most probably referred to the vibration of the cantilever (see how an AFM works), while the other unit is not Amps but Angstrom (1Å = 0.1nm). The pentacene molecule is long roughly 17Å. This stuff is on another planet of cool.
  • by je ne sais quoi (987177) on Friday August 28, 2009 @09:45AM (#29230857)
    Also the physioelectronic structure of the cu(111) is diffuse enough such that you can't easily resolve individual atoms. Each copper atom is so heavily bonded to it's neighbor that there is very little difference from one atom to the next. If you think about it, that makes sense since copper is a conductor, so the electrons must be able to move from one atom to the next easily. Graphite on the other hand (polymerized carbon like the pentacene here) is an insulator -- much less overlap between the orbitals of neighboring atoms.
  • Re:Impressive (Score:3, Informative)

    by mapsjanhere (1130359) on Friday August 28, 2009 @10:02AM (#29231091)
    I fail to see the novelty of this, it's another little incremental improvement in AFM resulution. They were able to image benzene rings with AFM 20 years ago; I remember in grad school one of the guys showing a video of them actually making a lot of substituted rings rearrange their layers on command, like a row of soldiers.
  • Re:Cool, but... (Score:3, Informative)

    by commodore64_love (1445365) on Friday August 28, 2009 @10:07AM (#29231183) Journal

    The other reason you can't take a picture of an electron is because photons of light are larger than the thing you are trying to image. Also you misquoted the uncertainly principle. It says you CAN find the precise location of an electron, but not its momentum. Or vice-versa find its momentum, but not position.

  • by MadTinfoilHatter (940931) on Friday August 28, 2009 @10:42AM (#29231705)
    The funny thing is that the first person to deduce this (Friedrich August Kekulé von Stradonitz) realized the solution to the problem of structure, after having a dream in which a snake bit its own tail.
  • by Myopic (18616) on Friday August 28, 2009 @12:37PM (#29233295)

    I think he wants you to check the surety of your conclusions. You stated that you "called into question" the results, and supported that with an observation, but the observation was easily explained by someone with basic knowledge of the thing you were questioning. So, since you knew that you were ignorant of this topic, but went ahead and drew a wrong conclusion, and did in fact question the veracity of the results, the person responded to you with mockery.

    Sure, you are allowed to use your eyes and draw conclusions. And when your conclusions are proffered with gusto, and are totally wrong, and based on ignorance, then you are open for a little criticism.

  • Re:Cool, but... (Score:5, Informative)

    by marcosdumay (620877) <marcosdumay&gmail,com> on Friday August 28, 2009 @12:40PM (#29233355) Homepage Journal

    Not exactly. If the electron is bounded, it has some specific momentum probabilities, and some specific position probabilities. You can't find its position with any different certainty unless you remove it from the bounded state.

    And that comes from the uncertainty principle. It is not just Dx * Dp >= h/(2 * pi). It is an statement that each state has some specific uncertanty, and that it isn't lower than that relation.

  • Re:Cool, but... (Score:4, Informative)

    by Timmmm (636430) on Friday August 28, 2009 @05:08PM (#29236933)

    Wrong again. The uncertainty principle is very badly named because it applies even if you know *everything* about the electrons and are uncertain about nothing.

    The problem is like trying to find the position and frequency of a wave packet. Both position and frequency are kind of macro quantities and it wouldn't make sense to fix them both at the same time. For example a wave with only one frequency must be the same everywhere and hence has no position. Conversely a delta function has an infinitely wide spectrum.

    http://en.wikipedia.org/wiki/Fourier_uncertainty_principle#Uncertainty_principle [wikipedia.org]

  • by Anonymous Coward on Friday August 28, 2009 @07:46PM (#29238405)

    I don't feel like logging in because it's a pain to look up my password, but I design AFM's.

    It would be trivial for them to have simply done a threshold on the image. It is readily possible to make graphene sheets of this level of local flatness.

In seeking the unattainable, simplicity only gets in the way. -- Epigrams in Programming, ACM SIGPLAN Sept. 1982

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