Collective Transport in Real-Time

Picture: A locomotive

In this research project, which was conducted by Delft University of Technology's Kavli Institute of Nanoscience, a small group of gold atoms were placed on a gold surface. The Delft researchers then used a High Resolution Electron Microscope (HREM) to show in real-time how this group of atoms collectively sank into the underlying layer of atoms and then became arranged in the shape of a surface dislocation (which is an extra row of atoms that is 'squeezed' between the other rows of atoms).

At a later stage, the dislocation disappears, as if a string of beads has been pulled away lengthwise. According to Professor Henny Zandbergen, this is the first time that such a phenomenon has been observed in real-time. This was possible due to the progress that has been made in recent years in image-forming techniques and the processing of the data.

According to Professor Zandbergen, the observable manner in which the atoms arranged themselves in the underlying layer and the movement of the dislocation is, in principle, an attractive way of transporting materials from the upper layer to the underlying layer and also within the underlying layer. Normally before an atom can 'hop' from one layer to the underlying layer, certain energy barriers exist. But such barriers do not exist with this manner of transport. The findings of this TU Delft research project clearly indicate that when people are modelling the (industrial) production of thin layers, they must also consider this type of collective processes.

Zandbergen's research is a typical example of the rapid progress currently being made by nano-microscopy, or nano-imaging. So far, this has primarily been observed under laboratory conditions. But soon live nano-imaging will take the next step to realistic and industrial conditions: real-life, real-time nano-imaging.; Source: Delft University of Technology