We focus on the experimental study of nanostructures, where the precise nature and location of every atom matters. We use low-temperature scanning probe microscopy that allow structural and electronic characterization and manipulation of materials down to the atomic scale.
Atomically well-defined graphene nanostructures
Graphene is a one-atom-thick planar sheet of carbon atoms packed into a honeycomb crystal lattice. In addition to the conceptual interest in a material that is just a single atom thick, researchers have been attracted to graphene due to its unique electronic properties. Graphene displays a host of quantum phenomena up to room temperature, such as the quantum Hall effect, which can usually only be observed at very low temperatures. This together with the high conductivity makes it very interesting for novel electronic devices.
We focus on fabrication and experimental characterization of atomically well-defined graphene nanostructures. Current topics of interest include graphene nanoribbons fabricated using on-surface polymerization reactions and atomically sharp, zigzag terminated graphene - hexagonal boron nitride interfaces.
Ultra-narrow metallic armchair graphene nanoribbons, Nature Communications 6, 10177 (2015).
Synthesis of Extended Atomically Perfect Zigzag Graphene - Boron Nitride Interfaces, Scientific Reports 5, 16741 (2015).
Electronic states at the graphene - hexagonal boron nitride zigzag interface, Nano Letters 14, 5128-5132 (2014).
Suppression of electron-vibron coupling in graphene nanoribbons contacted via a single atom, Nature Communications 4, 2023 (2013).
Single molecule chemistry and physics
It is well known that STM and AFM routinely offer atomic scale information on the geometric and the electronic structure of solids. Recent developments in STM and especially in non-contact AFM have allowed imaging and spectroscopy of individual molecules on surfaces with unprecedented spatial resolution, which makes it possible to study chemistry and physics at the single molecule level.
We use low-temperature scanning probe techniques for a complete physicochemical characterization of molecules and chemical reactions at the single-molecule level: measure the energy and spatial distribution of the frontier molecular orbitals, probe the overall electron density of the molecule that reveals the atomic structure and bonds, detect charges and investigate charge distributions and use lateral atomic and molecular manipulation to directly synthesize the target molecule.
Many-body transitions in a single molecule visualized by scanning tunnelling microscopy, Nature Physics 11, 229-234 (2015).
Atomic-Scale Contrast Formation in AFM Images on Molecular Systems, Noncontact Atomic Force Microscopy, Volume 3, ISBN 978-3-319-15588-3 3, 173-194 (2015).
Single-molecule chemistry and physics explored by low-temperature scanning probe microscopy, Chemical Communications 47, 9011-9023 (2011).
This topics are studied in collaboration with the Quantum Many-Body Physics, Surfaces and Interface at the Nanoscale and Surface Science research groups at the Department of Applied Physics, the Organometallic and Synthetic Organic Chemistry group at the Department of Chemistry and the Condensed Matter and Interfaces research group at the Utrecht University.