Nanoscale Science Department
Research efforts in the Department are centered on nanoscale science and technology with a focus on the bottom-up paradigm. The aim of the interdisciplinary research at the interface between physics, chemistry and biology is to gain control of materials at the atomic and molecular level, enabling the design of systems and devices with properties determined by quantum behavior on one hand and approaching functionalities of living matter on the other hand.
To better understand and possibly control fast chemical reactions, it is necessary to study the behavior of electrons as precisely as possible - at their intrinsic length and time scales. Until now, however, microscopy techniques have only provided sharp images in either space or time. Using a unique combination of tunneling microscopy and attosecond technology, we have managed to overcome these difficulties. Our atomic quantum microscope can visualize the movement of electrons in individual molecules, simultaneously at picometer length and attosecond time scales.
Molecular imaging at the single-molecule level of large and flexible proteins such as monoclonal IgG antibodies is possible by low-energy electron holography after chemically selective sample preparation by native electrospray ion beam deposition (ES-IBD) from native solution conditions. The single-molecule nature of the measurement with a spatial resolution down to 5 Å allows the mapping of the structural variability of the protein molecules that originates from their intrinsic flexibility and from different adsorption geometries.
Molecules colliding with surfaces at energies relevant to chemistry (0 – 50 eV) undergo selective conformation changes and mechanochemical reactions. The origin of these phenomena is the compression of the molecules when the fast-approaching molecules are brought to sudden halt upon their impact at the surface. Our novel approach offers a general pathway to explore the conformation space and the mechanochemistry of any molecule that can be electrosprayed.
Despite plenty of room at the bottom, there is a limit to the miniaturization of every process. Using scanning tunneling microscopy, we have exploited a magnetic impurity at a superconducting tip and one on a superconducting sample to demonstrate tunneling between two energy levels as a minimal configuration of a tunneling current. The underlying theory, which was developed together with colleagues from Ulm and Madrid, becomes surprisingly simple and allow us to extract the rather long lifetime of the Yu-Shiba-Rusinov states.