Bending world's thinnest glass shows atoms' dance for first time (w/ Video)

Oct 10, 2013
The trajectories of atoms in silica glass as it deforms, overlaid on a transmission electron microscopy image. Credit: Cornell University

(Phys.org) —Watch what happens when you bend and break the world's thinnest glass. This glass, discovered by Cornell University researchers and their international team of collaborators, was recently featured in the Guinness Book of World Records and is made of the same compounds as everyday windowpanes.

Now, a research team led by both David A. Muller, professor of applied and engineering physics and co-director of the Kavli Institute at Cornell for Nanoscale Science, and Ute Kaiser, professor at the University of Ulm, has used an to bend, deform and melt the one-molecule-thick glass. These are all things that happen just before glass shatters, and for the first time, the researchers have directly imaged such deformations and the resulting "dance" of rearranging in . This newest work is published Oct. 11 in the journal Science.

Even though glass is a common material, it is notoriously hard to study, said Pinshane Huang, a graduate student working with Muller and the paper's first author. Glass is known as an amorphous solid because its atoms are rigid like a crystal but disordered like a liquid. "This thinnest-ever glass gives us a new way of looking at glass and how it breaks, atom by atom, " Huang said.

Said Muller: "No one has ever before been able to see how the atoms in a glass rearrange when you push on them." Sophisticated theories describe how these atoms behave when bent or broken, but the theories have been difficult to verify, said Jim Sethna, professor of physics and paper co-author. "Lots of people have made computer simulations, but this is the experimental realization of what the glass community has been looking for a long, long time," Sethna said.

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The Cornell University video taken via electron microscopy shows a single atom ring rearrangement, one of the basic building blocks of plastic deformation in glass. Credit: Cornell University

With collaborators at Cornell and Germany's University of Ulm, the researchers imaged the thin glass with a . The researchers shot a beam of high-energy electrons at the glass, causing visible structural deformation. Muller described the electrons as "tickling" the glass in order to deform it and simultaneously image what was happening. "We had all of these pictures of the glass, and when we strung them together into videos, we were surprised to see the atoms wiggling and jiggling around. We realized that we were looking at the building blocks for how glass deforms," said Huang, "Everyone thought it was impossible to see atoms moving in a glass, and suddenly we were able to do it with this new, ultrathin glass."

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A Cornell University video from a transmission electron microscope shows glass melting and re-forming at the edge. Yellow and blue false coloring highlight the solid and melted regions, respectively.

"You could say, we have identified some of the basic dance moves," Muller added.

The researchers found something else unexpected: Parts of the glass melted under the electron beam, forming moving boundaries between solid and molten glass. "We don't understand deeply why glasses are solid. An experiment that lets us watch it freeze could be revealing," said Sethna.

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A Cornell University video from a transmission electron microscope shows atoms shearing apart. The colors indicate four regions that behave differently.

These insights may eventually lead to atom-by-atom designs for stronger panes or more robust transistors.

Explore further: Guinness record: World's thinnest glass is just two atoms thick

More information: "Imaging Atomic Rearrangements in Two-Dimensional Silica Glass: Watching Silica's Dance," by P.Y. Huang et al. Science, 2013.

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NikFromNYC
1.6 / 5 (10) Oct 10, 2013
Real link for Phys.org's shamefully lame-ful slack, with more videos of real room temperature atom dynamics (sped up 10X):
http://www.scienc...uppl/DC1
Eikka
5 / 5 (1) Oct 11, 2013
What is surprising for me is, that the atoms wiggle quite slowly


They don't. That's just an artifact of the low sampling rate of the video, or more commonly known as the wagon wheel effect.

The atoms jiggle about very rapidly, so when you go and measure them, you get a blurred blotch that corresponds to where they are roughly on average. The blobs you see in the video are not individual atoms.

That average depends on how long a time you took to measure the atom, which means that on a video where each frame is a measurement over half a second, no movement faster than half a second is visible and therefore the atom-blobs appear to move quite slowly. The slower you measure, the slower they move and the more blurry the picture you get.
Mike_Massen
not rated yet Oct 17, 2013
@Franklins
The article you link to states
The original frame rate is 0.5 frames per second; movie is
sped up 10x. All video formats are .avi with jpeg compression.
which indicates a very low rate of sampling. They also state
Experiments are conducted at room temperature.
which at those small dimensions would impart most significant vibrations at rates much faster than visible, so yes Eikka is correct (on this occasion) ;-)