Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New form of electron-beam imaging can see elements that are 'invisible' to common methods

29.02.2016

Berkeley Lab-pioneered 'MIDI-STEM' produces high-resolution views of lightweight atoms

Electrons can extend our view of microscopic objects well beyond what's possible with visible light--all the way to the atomic scale. A popular method in electron microscopy for looking at tough, resilient materials in atomic detail is called STEM, or scanning transmission electron microscopy, but the highly-focused beam of electrons used in STEM can also easily destroy delicate samples.


In MIDI-STEM (right), developed at Berkeley Lab, an electron beam travels through a ringed "phase plate," producing a high-resolution image (bottom right) that provides details about a sample containing a heavy element (gold) and light element (carbon). Details about the carbon are missing in an image (bottom left) of the sample using a conventional electron imaging technique (ADF-STEM).

Credit

(Colin Ophus/Berkeley Lab, Nature Communications: 10.1038/ncomms10719)

This is why using electrons to image biological or other organic compounds, such as chemical mixes that include lithium--a light metal that is a popular element in next-generation battery research--requires a very low electron dose.

Scientists at the Department of Energy'sc Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a new imaging technique, tested on samples of nanoscale gold and carbon, that greatly improves images of light elements using fewer electrons.

The newly demonstrated technique, dubbed MIDI-STEM, for matched illumination and detector interferometry STEM, combines STEM with an optical device called a phase plate that modifies the alternating peak-to-trough, wave-like properties (called the phase) of the electron beam.

This phase plate modifies the electron beam in a way that allows subtle changes in a material to be measured, even revealing materials that would be invisible in traditional STEM imaging.

Another electron-based method, which researchers use to determine the detailed structure of delicate, frozen biological samples, is called cryo-electron microscopy, or cryo-EM. While single-particle cryo-EM is a powerful tool--it was named as science journal Nature's 2015 Method of the Year --it typically requires taking an average over many identical samples to be effective. Cryo-EM is generally not useful for studying samples with a mixture of heavy elements (for example, most types of metals) and light elements like oxygen and carbon.

"The MIDI-STEM method provides hope for seeing structures with a mixture of heavy and light elements, even when they are bunched closely together," said Colin Ophus, a project scientist at Berkeley Lab's Molecular Foundry and lead author of a study, published Feb. 29 in Nature Communications, that details this method.

If you take a heavy-element nanoparticle and add molecules to give it a specific function, conventional techniques don't provide an easy, clear way to see the areas where the nanoparticle and added molecules meet.

"How are they aligned? How are they oriented?" Ophus asked. "There are so many questions about these systems, and because there wasn't a way to see them, we couldn't directly answer them."

While traditional STEM is effective for "hard" samples that can stand up to intense electron beams, and cryo-EM can image biological samples, "We can do both at once" with the MIDI-STEM technique, said Peter Ercius, a Berkeley Lab staff scientist at the Molecular Foundry and co-author of the study.

The phase plate in the MIDI-STEM technique allows a direct measure of the phase of electrons that are weakly scattered as they interact with light elements in the sample. These measurements are then used to construct so-called phase-contrast images of the elements. Without this phase information, the high-resolution images of these elements would not be possible.

In this study, the researchers combined phase plate technology with one of the world's highest resolution STEMs, at Berkeley Lab's Molecular Foundry, and a high-speed electron detector.

They produced images of samples of crystalline gold nanoparticles, which measured several nanometers across, and the super-thin film of amorphous carbon that the particles sat on. They also performed computer simulations that validated what they saw in the experiment.

The phase plate technology was developed as part of a Berkeley Lab Laboratory Directed Research and Development grant in collaboration with Ben McMorran at University of Oregon.

The MIDI-STEM technique could prove particularly useful for directly viewing nanoscale objects with a mixture of heavy and light materials, such as some battery and energy-harvesting materials, that are otherwise difficult to view together at atomic resolution.

It also might be useful in revealing new details about important two-dimensional proteins, called S-layer proteins, that could serve as foundations for engineered nanostructures but are challenging to study in atomic detail using other techniques.

In the future, a faster, more sensitive electron detector could allow researchers to study even more delicate samples at improved resolution by exposing them to fewer electrons per image.

"If you can lower the electron dose you can tilt beam-sensitive samples into many orientations and reconstruct the sample in 3-D, like a medical CT scan. There are also data issues that need to be addressed," Ercius said, as faster detectors will generate huge amounts of data. Another goal is to make the technique more "plug-and-play," so it is broadly accessible to other scientists.

###

Berkeley Lab's Molecular Foundry is a DOE Office of Science User Facility. Researchers from the University of Oregon, Gatan Inc. and Ulm University in Germany also participated in the study.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.lbl.gov/.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov.

Media Contact

Glenn Roberts Jr.
geroberts@lbl.gov
510-486-5582

 @BerkeleyLab

http://www.lbl.gov 

Glenn Roberts Jr. | EurekAlert!

Further reports about: Molecular biological samples cryo-EM electron microscopy electron-beam

More articles from Physics and Astronomy:

nachricht Molecule flash mob
19.01.2017 | Technische Universität Wien

nachricht Magnetic moment of a single antiproton determined with greatest precision ever
19.01.2017 | Johannes Gutenberg-Universität Mainz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland

19.01.2017 | Earth Sciences

Not of Divided Mind

19.01.2017 | Life Sciences

Molecule flash mob

19.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>