Microscope Sees Molecules for First Time

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For the first time, IBM was able to take real images of a molecule. These pentacene molecules are shown on an Angstrom (10^-10 m) scale.

For the first time, IBM was able to take real images of a molecule. These pentacene molecules are shown on an Angstrom (10^-10 m) scale.

Imagine trying to read braille printed on wet tissue paper. That’s what it’s been like trying to take a picture of a molecule. Advanced electron microscopes can get amazing resolution, fine enough to see inside an atom, but molecular bonds usually aren’t strong enough to hold up to their scrutiny. Luckily, a team of researchers at IBM has produced the first Atomic Force Microscope (AFM) with a carbon monoxide tip. Using this new device, they’ve produced the first real images of a molecule. Check out the pics of the pentacene molecule, they’re one of a kind.

Being able to examine a molecule without it falling apart is a first step into understanding how to manipulate those molecules with precision. Pentacene has uses as an organic semiconductor. IBM has had success with microscopy in the past, and thinks its research will pave the way for designing and building electronic devices at the atomic level. One day, entire computers and even everyday objects could be manufactured from the atom up, allowing for incredible breakthroughs in processing power and efficiency.

Traditional microscopes like the one you had in middle school science class use visible light to illuminate a sample. Electron microscopes,which have been around since the 30s, use high powered electrons to image objects in a similar way. AFMs, however, work like fingers reading braille. They use a microscopic tip to gently run over the surface of a sample and then measure how the tip fluctuates. In this way, they build a “force-map” or textured view of what the tip passes over.

Using a carbon monoxide tip (red/gray) the IBM atomic force microscope could pass over pentacene and image it succesfully for the first time.

Using a carbon monoxide tip (red/gray) the IBM atomic force microscope could pass over pentacene and image it succesfully for the first time.

AFMs have been around since 1986, but they haven’t been able to image a molecule. Electrostatic and Van der Waals forces cause molecules and AFM tips to interact, ether destroying the sample or disrupting the readings. IBM overcame this problem by attaching a single carbon monoxide (CO) molecule to their AFM tip. Thanks to quantum mechanics, the CO and pentacene molecules have their electrons set up in a way that helps cancel out electrostatic and Van der Waals forces. In other words, the tip can pass over the sample without messing it up. The result is the first image of its kind.

Like all new microscopy techniques, the modified AFM has its set backs. First, like the electron microscope or traditional AFM, the IBM setup can’t be done in the open air. You need a very high level vacuum, absurdly low temperatures (5 Kelvin), and a lot of time – more than 20 hours for a scan. The tip also has to be within 0.5 nanometers of the sample. But the most fundamental problem is that the carbon monoxide trick won’t work for every sample type. The quantum mechanics principles that keep the tip and sample from interacting wouldn’t help for say, a strand of DNA. Of course, there are a bunch of different tips you could use, so there may be a tip for every sample you could want to examine.

As cool as it is to see a molecule up close and personal, you can bet IBM has bigger plans. Quantum computing, which is seeming less and less like science fiction everyday, will require building structures at the molecular level. With the modified AFM, we’ll get a better understanding of what’s happening at that level and how best to create computers at a nano-sized scale. That’s going to translate into better efficiency and processing speeds that make a modern computer chip look like an abacus.

Of course, even with the best views of the microscopic world quantum computing is years away from beginning. For now, we’ll have to be happy with having a better view of a pentacene molecule. Hopefully, IBM will adapt their technique to see many different nano-sized structures. It may not happen today, but work like this will help us build the tiny, magnificent world of the future.

We've been able to model pentacene for a long time (TOP), but actually seeing it is amazing (BOTTOM).

We've been able to model pentacene for a long time (TOP), but actually seeing it is amazing (BOTTOM).

[photo credits: IBM]

Discussion — 9 Responses

  • Karganeth September 1, 2009 on 8:09 pm

    Not a microscope >.<

  • Karganeth September 1, 2009 on 4:09 pm

    Not a microscope >.<

  • Keith Kleiner September 1, 2009 on 10:04 pm

    not one that uses light…but still absolutely a microscope

  • Keith Kleiner September 1, 2009 on 6:04 pm

    not one that uses light…but still absolutely a microscope

  • robot makes music September 1, 2009 on 10:19 pm

    Electron microscopes have been around since the 30s, actually. Siemens built the first commercial on in 1939.

    And yes, as the name “Atomic Force Microscope” implies, it is indeed considered a microscope.

    However, I need to take issue with you saying that electron microscopes operate in open air, which is not true. You need at least a low vacuum to operate one (if you have a special environmental SEM), in more common practice you need a high vacuum, around 6×10^-6 Torr. In the cases of fancier scopes (that is, one with exotic electron sources) you need multiple vacuums, the one at the electron source exceeding 10^-11 Torr (also known as ultra-high vacuum).

    I’m kinda surprised that STEMs can’t be used to image these molecules, they have a lateral resolution down into the Angstrom or sub-angstrom range, but perhaps they too destroy the sample, as they are running a quantum tunneling current through the material (or something like that).

    MRFM, magnetic resonance force microscopy doesn’t have resolution down this low yet, but may achieve it – it’s very similar to how AFM works, but can image in 3 dimensions, and as it operates in the same ultra-high vacuum, ultra-cold temperatures as this AFM mode, perhaps the same sharpening techniques could be applied.

    • Aaron Saenz robot makes music September 1, 2009 on 10:27 pm

      @Robot Makes Music
      Sorry about the mix-up between TEM and SEM (which have been around since the 30s) and STEM which was developed in the 70s (though it too had its start in the 30s). I did a quick edit to fix.

      Moving forward, I think you may have misread my sentence: “…First, like the electron microscope or traditional AFM, the IBM setup can’t be done in the open air. You need a very high level vacuum, absurdly low temperatures (5 Kelvin), and a lot of time – more than 20 hours for a scan.” – The sentence construction here isn’t the clearest, I know. My intent, however, was to allude to what you discussed in your comment. That is, all of these techniques require a lot of prep work and specialized conditions in order to succeed.

  • robot makes music September 1, 2009 on 6:19 pm

    Electron microscopes have been around since the 30s, actually. Siemens built the first commercial on in 1939.

    And yes, as the name “Atomic Force Microscope” implies, it is indeed considered a microscope.

    However, I need to take issue with you saying that electron microscopes operate in open air, which is not true. You need at least a low vacuum to operate one (if you have a special environmental SEM), in more common practice you need a high vacuum, around 6×10^-6 Torr. In the cases of fancier scopes (that is, one with exotic electron sources) you need multiple vacuums, the one at the electron source exceeding 10^-11 Torr (also known as ultra-high vacuum).

    I’m kinda surprised that STEMs can’t be used to image these molecules, they have a lateral resolution down into the Angstrom or sub-angstrom range, but perhaps they too destroy the sample, as they are running a quantum tunneling current through the material (or something like that).

    MRFM, magnetic resonance force microscopy doesn’t have resolution down this low yet, but may achieve it – it’s very similar to how AFM works, but can image in 3 dimensions, and as it operates in the same ultra-high vacuum, ultra-cold temperatures as this AFM mode, perhaps the same sharpening techniques could be applied.

    • Aaron Saenz robot makes music September 1, 2009 on 6:27 pm

      @Robot Makes Music
      Sorry about the mix-up between TEM and SEM (which have been around since the 30s) and STEM which was developed in the 70s (though it too had its start in the 30s). I did a quick edit to fix.

      Moving forward, I think you may have misread my sentence: “…First, like the electron microscope or traditional AFM, the IBM setup can’t be done in the open air. You need a very high level vacuum, absurdly low temperatures (5 Kelvin), and a lot of time – more than 20 hours for a scan.” – The sentence construction here isn’t the clearest, I know. My intent, however, was to allude to what you discussed in your comment. That is, all of these techniques require a lot of prep work and specialized conditions in order to succeed.

  • Nikhil Melgiri November 15, 2010 on 11:26 pm

    Wow!!! you must of worked very hard on this. The future is improving