Researchers from the University of Antwerp, Centrum Wiskunde & Informatica (CWI) and Switzerland have developed a new method to visualize individual atoms inside tiny particles. They applied sophisticated measuring techniques to advanced electron microscopy images. Their research, published in Nature on 02 February 2011, will allow researchers to better understand the three-dimensional structure of materials. This research is important for the development of new catalysts, solar cells and better LED lighting.

Counting atoms
Nanoparticles are structures consisting of only a few atoms up to thousands of atoms, ranging in size from 1 to 100 nanometer. Nanoparticles often have physical, chemical, or biological properties that are very different from the same materials at larger scale. For example, gold changes colour from yellow to red as the size of the gold particles is reduced to a few nanometer. The often unexpected properties depend on the exact three-dimensional structure of all atoms inside the nanoparticle. Therefore, it has been a long-term challenge to zoom down to the atomic level. For the first time, scientists managed to make this dream come true.

They applied sophisticated arithmetic algorithms to images of a silver nanoparticle obtained with one of the most powerful electron microscopes around the world. By imaging this particle under different directions and applying innovative measurement techniques, the complete atomic structure can be visualized in three dimensions. Advanced mathematical techniques for discrete tomography made it possible to compute the 3D reconstruction out of only a few microscopic images.

International team
The research was performed at the EMAT laboratory (Electron Microscopy for Materials Science) of the University of Antwerp – under the guidance of Sandra Van Aert and Gustaaf Van Tendeloo – and at the Centrum Wiskunde & Informatica in Amsterdam – under the guidance of Joost Batenburg. The research team also included scientists from Switzerland, Rolf Erni and Marta Rossell, who acquired experimental images with a prototype of the new Qu-Ant-EM electron microscope which is in use since Antwerp since June 2010.

Their research pushes the limits of our perception and will promote the ongoing research on nanoparticles in particular. The possibility to visualize the three-dimensional structure of nanoparticles at the atomic level will open up new possibilities in the development of innovative materials with revolutionary interesting properties. One will be able, for example, to acquire all necessary knowledge to understand the structure and activity of catalysts and to design optimal catalysts, for example for use in the automobile industry. Furthermore, knowledge about the atomic structure holds promises for the development of more efficient solar cells, computer chips, versatile lasers and brighter LED lighting.

Illustration: Visualization of the three-dimensional structure of a silver nanoparticle at an atomic level. Sophisticated measurement techniques are applied to images obtained with one of the most powerful electron microscopes in the world.

- The Nature article appears on 2 February 2011 after 19.00h on  http://dx.doi.org/10.1038/nature09741 and on http://www.nature.com/