We explore the cornupia of new physics that can be accessed with the latest developments in the materials sciences, in particular low-dimensional (two-dimensional) new materials, in combination with cutting edge microscopy. Graphene, a single layer of carbon atoms, is currently at the center of interest because it is a particularly outstanding new material that also promises a wide range of new applications. It features an extraordinary electronic structure, a record mechanical stability, highest current carrying capabilities and thermal conductivity, the largest surface area per volume as well as a relatively inert surface.

 

Freely suspended mono-layer graphene is the thinnest possible membrane that is conceivable with currently known materials. Yet, it is remarkably stable under high-energy electron irradiation, and thus opens unprecedented opportunities also for electron microscopic studies. The graphene membrane structure and its defects are of outstanding interest for science and applications of this promising new material. Static deformations, topological defects, various vacancy configurations, substitutional dopants or the two-dimensional equivalent of dislocations have been studied by transmission electron microscopy (TEM). The formation and evolution of defects under electron irradiation is observed in real time with atomic resolution. High-energy electron irradiation provides a continuous "randomization" of some atoms, which then allows new insights into the complicated bonding behaviour in carbon materials. Further, graphene membranes can serve as a perfect sample support for transmission electron microscopy. Its contribution to the TEM image signal can be filtered out completely and adsorbed atoms and molecules on the graphene sheet can be imaged as if they were suspended in free space.

 

The remarkable developments in electron microscopy over the past few years, in particular the correction of lens aberrations⁠ and reduction of electron energies, have enabled the direct imaging of the exact atomic structure even in materials made of light elements and of low dimensionality. We can now study these materials with unprecedented precision and follow dynamic processes in in-situ experiments. Exploring new avenues in this direction is one part of our research focus.