Orbitals of a carbon atom, as seen
by a field-emission microscope.
Image: From "Imaging the atomic orbitals of carbon atomic chains with field-emission electron microscopy," by I. M. Mikhailovskij, E. V. Sadanov, T. I. Mazilova, V. A. Ksenofontov and O. A. Velicodnaja, in PHYSICAL REVIEW B, Vol. 80, NO. 16; October 2009
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Chemistry textbooks typically include illustrations of atoms, but with caveats. The drawings depict atomic nuclei surrounded by electron orbitals—fuzzy spheres, barbells, tripods, and so on—but those figures represent the probability of finding an electron at a certain place around the nucleus rather than an actual “shape.” Researchers have now managed to image the electron orbitals and show for the first time that, in a sense, atoms really look like those textbook images.
Specifically, Igor Mikhailovskij and his collaborators at the Kharkov Institute of Physics and Technology in Ukraine have imaged the shapes of those orbitals in carbon atoms by improving an old imaging technique called field-emission microscopy.
The researchers fashioned a chain of carbon atoms, dangled it from a graphite tip, and then placed it in front of a detection screen. When they applied an electric field of thousands of volts between the graphite and the screen, electrons flowed one by one through the graphite and along the carbon chain, until the electric field pulled them off the last atom in the chain. From the places where the electrons landed on the screen, the investigators could trace back the points where they left their orbital on the last atom. The “denser” parts of the probability clouds had a higher chance of emitting an electron, and the information from many electrons combined into an image of the clouds. “We really have an image of single atoms,” Mikhailovskij says.
The pictures look, well, textbook, although only the outermost orbitals appear, which shroud the inner orbitals and the nuclei. By changing the intensity of the current, the team could switch the energy of the last atom’s outermost electron from a lower level to a higher level. Correspondingly, the shape of the orbital changed from spherical to barbell, as theory predicts. The group also observed electrons switching spontaneously from one state to another—for reasons that are unclear, Mikhailovskij says—and stranger shapes that may result from the presence of impurities, in the form of other atoms such as hydrogen. The results are in the October Physical Review B.
Scientists have imaged single atoms before, using tools such as transmission electron microscopes (which shoot electrons through an object and measure how they get deflected) or scanning tunneling microscopes (which “feel” the sample’s shape with a microscopic tip).
But the atoms typically appeared as little more than blobs. Field-emission microscopy, on the other hand, pulls the electrons off the very object that is being imaged. This difference, says Alex Zettl of the University of California, Berkeley, may mean a lower chance of distortions and misinterpretations of the signal. “It is like hearing the spoken word directly from the original storyteller, not from a translator or interpreter,” he says.
Beyond confirming textbook artwork, the technique could elucidate the properties of chains of carbon atoms, which are still largely unknown. Physicists suspect that they may be excellent conductors and mechanically strong and could become useful in future atomic-scale computers.
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12 Comments
Add CommentThat's nice, now show me gravity
Reply | Report Abuse | Link to thisWow! Last month the Large Binocular telescope for seeing big things far awayand now this revised/improved microscopic method for seeing small things real close. And yet we still can't see what's right in front of us underwater and more than twenty feet away..
Reply | Report Abuse | Link to thisTry wearing polaroid sunglasses, Michael. You'll find they cut the surface glare and make water much easier to see into.
Reply | Report Abuse | Link to thisUm, I think I do speak of being underwater as stated and trying to see things twenty feet away. If I was unclear about that , sorry, and thanks for caring enough to offer a solution.
Reply | Report Abuse | Link to thisMichael
What happened to the Hiesenberg principle,did I spell that right?
Reply | Report Abuse | Link to thisjack.123, how goes the job search?
Reply | Report Abuse | Link to thisExcellent point here about uncertainty. Not only are we only seeing an average population result and not individual particles, there is the unknown of what may have influenced the electrons path dropping from the end of the carbon chain to the exposure/reaction surface. As far as anyone knows, there could have been a solar storm of neutrinos which greatly influenced the paths.
Yes, I think Heisenberg is still a safe principle.
Michael-Still looking,hope to get a job soon.Getting fat need to get back to work soon,my health isn't helping any.Hope your not having the same problems.I see they are still having problems at CERN.It seems like maybe the Heisenberg principle/universe has something were not suppose to see?What a mess its going to be if Higgs isn't found.Guess they will have to start over with some new theorys.
Reply | Report Abuse | Link to thisOr a bigger machine.
Reply | Report Abuse | Link to thisyeah, a graviton might be nice.
Reply | Report Abuse | Link to thisI am not quite sure ,but the curve of space-time alone might be the cause of gravity,due to the displacement of it by mass.Although the finding of graviton would lead to a lot of new research of whats going on in the universe,either way were about to find out a lot new of things about whether T.O.E. theorys are right or wrong.
Reply | Report Abuse | Link to thisBack to the 'Scope, my education recollection of electron position depiction (wow four "ions" & an 'on' in one sentence talking about.... ions) was that the electrons were in shells. It was the expanding and contraction of the shells that gave off radiation or absorbed it. When I look at image #2 above I don't see how that process can occur. Can anyone explain this "Chemistry" conundrum? Or do I need to go to a Physicist?
Reply | Report Abuse | Link to thisSharp Fudge
Reply | Report Abuse | Link to thisFantastically sharp images of electron orbitals shown in The Shape of Atoms just serve to highlight the fudge that we all blindly accept. Heisenbergs Uncertainty principle is a science cop-out. A statistical explanation is merely a practical side step so that we can get on with other stuff. We should prod and poke more at the problem itself. What hypotheses are out there that offer a potential model for subatomic indeterminacy?
Space-time oscillation at quantum scale could explain the mystery. If quantised time itself oscillated then it would be devilishly hard (but not impossible) to picture where an electron would be next. For all practical purposes we would need to fall back on statistics unless someone can model this extra dimensional oscillation. For beings grounded in space, and only privy to the now of time, Newtonian predictability would be massively confused if causality took an invisible walk, at an unknown speed, in an undetectable direction. However, it is my hope that some budding student, or professor can devise a model that would make this scenario comprehensible. Perhaps then they will be able to make verifiable predictions. What if quantum objects are actually flipping minutely into the past and then into the future, passing through now, on the way. What if we could isolate just the past particles, or the future ones? What would it mean if you had captured a whole bunch of future particles ? Food for thought&?