New microscopy technique improves imaging at the atomic scale

Jan 23, 2014 by Matt Shipman
A new technique developed at North Carolina State University effectively eliminates distortion from atomic-scale images taken with scanning transmission electron microscopes. Credit: James LeBeau

(Phys.org) —When capturing images at the atomic scale, even tiny movements of the sample can result in skewed or distorted images – and those movements are virtually impossible to prevent. Now microscopy researchers at North Carolina State University have developed a new technique that accounts for that movement and eliminates the distortion from the finished product.

At issue are scanning transmission electron microscopes (TEMs), which can capture of a material's individual atoms. To take those images, scientists have to allow a probe to scan across the area – which has an area of less than five nanometers. That scanning can take tens of seconds.

The sample rests on a support rod, and while the scanning takes place the rod expands or contracts due to subtle changes in ambient temperature. The rod's expansion or contraction is imperceptible to the naked eye, but because the sample area is measured in nanometers the rod's movement causes the sample material to shift slightly. This so-called "drift" can cause the resulting scanning TEM images to be significantly distorted.

"But our approach effectively eliminates the effect of drift on scanning TEM images," says Dr. James LeBeau, an assistant professor of materials science and engineering at NC State and senior author of a paper describing the work.

Researchers programmed the microscope to rotate the direction in which it scans the sample. For example, it might first take an image scanning from left to right, then take one scanning from top to bottom, then right to left, then bottom to top. Each scanning direction captures the distortion caused by drift from a different vantage point.

The researchers plug those images into a program they developed that measures the features in each image and uses that data to determine the precise direction and extent of drift within the sample. Once the drift is quantified, the images can be adjusted to remove the distortion caused by the drift. The resulting images accurately represent the actual structure of the sample and give scientists new capabilities to understand bonding between atoms.

"Historically, a major problem with drift has been that you need to have a reference material in any nanoscale image, so that you can tell how the image has been distorted," LeBeau says. "This technique makes that unnecessary. That means we can now look at completely unknown samples and discover their crystalline structures – which is an important step in helping us control a material's physical properties."

Explore further: New technique efficiently resolves chemistry of nanoparticles

More information: The paper, "Revolving scanning transmission electron microscopy: correcting sample drift distortion without prior knowledge," will be published in the March issue of Ultramicroscopy. www.sciencedirect.com/science/article/pii/S0304399113003161

Related Stories

Nanoparticles digging the world's smallest tunnels

Jan 23, 2013

The world's smallest tunnels have a width of a few nanometers only. Researchers from Karlsruhe Institute of Technology (KIT) and Rice University, USA, have dug such tunnels into graphite samples. This will ...

Recommended for you

First direct observations of excitons in motion achieved

Apr 16, 2014

A quasiparticle called an exciton—responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits—has been understood theoretically for decades. But exciton ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

clay_ferguson
5 / 5 (2) Jan 23, 2014
Ingenious, yet sort of obvious solution to the problem! This should be, however almost something worthy of a Nobel Prize, because it makes subatomic materials now clearly visible rather than fuzzy images. Absolutely amazing. Should have a massive impact on nanotechnology of all kinds.
jimbo92107
5 / 5 (1) Jan 23, 2014
Same technique should allow them to synthesize parallax in three dimensions, so they can view the sample in 3D. I wonder if these guys ever have coffee with astronomers...

More news stories

Thinnest feasible nano-membrane produced

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...