On the basis of these microscopic images, Sandra Van Aert from the University of Antwerp created models that sharpened the images and enabled them to be quantified: the refined images made it possible to count the individual silver atoms along different crystallographic directions.
For the three-dimensional reconstruction of the atomic arrangement in the nanoparticle, Rossell and Erni eventually enlisted the help of the tomography specialist Joost Batenburg from Amsterdam, who used the data to tomographically reconstruct the atomic structure of the nanoparticle based on a special mathematical algorithm. Only two images were sufficient to reconstruct the nanoparticle, which consists of 784 atoms. Up until now, only the rough outlines of nanoparticles could be illustrated using many images from different perspectives, says Marta Rossell. Atomic structures, on the other hand, could only be simulated on the computer without an experimental basis.
Applications for the method, such as characterising doped nanoparticles, are now on the cards, says Rolf Erni. For instance, the method could one day be used to determine which atom configurations become active on the surface of the nanoparticles if they have a toxic or catalytic effect. Rossell stresses that in principle the study can be applied to any type of nanoparticle. The prerequisite, however, is experimental data like that obtained in the study.
|Contact: Dr. Rolf Erni|
Swiss Federal Laboratories for Materials Science and Technology (EMPA)