Scientists use electron microscopy to resolve and identify individual light atoms

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Washington, March 25 (ANI): In a new research, a team of scientists, using the latest in aberration-corrected electron microscopy, have obtained the first images that distinguish individual light atoms such as boron, carbon, nitrogen and oxygen.

The research was carried out by scientists at the Department of Energy's Oak Ridge National Laboratory (ORNL), US.

The ORNL images were obtained with a Z-contrast scanning transmission electron microscope (STEM).

Individual atoms of carbon, boron, nitrogen and oxygen - all of which have low atomic numbers - were resolved on a single-layer boron nitride sample.

"This research marks the first instance in which every atom in a significant part of a non-periodic material has been imaged and chemically identified," said Materials Science and Technology Division researcher Stephen Pennycook.

"It represents another accomplishment of the combined technologies of Z-contract STEM and aberration correction," he added.

The new high-resolution imaging technique enables materials researchers to analyze, atom by atom, the molecular structure of experimental materials and discern structural defects in those materials.

Defects introduced into a material are often responsible for the material's properties.

The group analyzed a monolayer hexagonal boron nitride sample prepared at Oxford University and was able to find and identify three types of atomic substitutions - carbon atoms substituting for boron, carbon substituting for nitrogen and oxygen substituting for nitrogen.

Boron, carbon, nitrogen and oxygen have atomic numbers-or Z values - of five, six, seven and eight, respectively.

The annular dark field analysis experiments were performed on a 100-kilovolt Nion UltraSTEM microscope optimized for low-voltage operation at 60 kilovolts.

Aberration correction, in which distortions and artifacts caused by lens imperfections and environmental effects are computationally filtered and corrected, was conceived decades ago but only relatively recently made possible by advances in computing.

Aided by the technology, ORNL's Electron Microscopy group set a resolution record in 2004 with the laboratory's 300-kilovolt STEM. (ANI)

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