Molecular Nanostructures at Surfaces – Jan Čechal

Functional supramolecular nanostructures at surfaces: UHV preparation and in situ characterization.

Graphene: active material for control electronic structure of adsorbates.

Multimethod surface analysis: LEEM, STM, XPS and ARPES.

Core scientific activities in our group joins two attractive fields: field of molecular self-assembly and field of graphene. In particular, we prepare supramolecular nanostructures on metal and graphene substrates and study both self-assembly process itself and functional properties of supramolecular layers in connection with molecular spintronic and catalysis. 

Further, we offer our expertise on surface analysis, in particular, analysis of chemical composition by X-ray photoelectron spectroscopy to collaborating partners.

Molecular self-assembly of surface confined architectures attracted significant attention for their promising applications in the fields of surface patterning, host guest chemistry, molecular electronics and spintronics, and as catalytic model systems. Here, the long-range ordered networks are formed on surfaces from elementary building blocks: organic molecules and metal atoms. The proper design of molecular building units and selection of metal atoms enables to engineer extended 2D structures bearing the desired functionality.

Graphene, a zero-bandgap semiconductor, attracted much interest for its mechanical, optical and electronic properties. From our point of view, the most exciting feature is the possibility to control its electronic properties, i.e., the type of charge carriers and their concentration, by the external electric field.

The research in the research group Molecular Nanostructures at Surfaces joins these attractive research fields. In particular, we utilize graphene as substrate for molecular self-assembly and explore the possibility to tune the graphene electronic properties to control of both self-assembly process itself and functional properties of supramolecular layers on graphene surface.

The research follows these parallel principal directions:

Long range ordered arrays of molecular quantum bits

Single molecular magnets (SMM) are molecular entities bearing nonzero magnetic moment. In addition to the magnetic properties SMM provide one important attribute: they represent two-state system that can be in superposition state, i.e., SMM represent quantum bits (qubits). The recent developments pushed the figure of merit (the coherence time divided by the time for a single quantum operation) over 10 000, i.e., the molecular magnets already present competitive basis for qubits. However, for any future application the molecular qubits should be processable as thin films. Moreover, the individual qubits should be mutually interacting.

In our group we explore the ways to prepare extended long-range ordered arrays of SMM, i.e., molecular qubits to form a basis for a molecular quantum registry.

Enzymatic mimics based metal-organic coordination networks

The coordinatively unsaturated metal atoms in the surface confined metal-organic coordination networks resemble active sites of enzymes (proteins that catalyze chemical reactions). Mimicking enzymatic systems on surfaces will potentially lead to discovery of novel efficient and selective catalytic systems. Recently, we have found that iron centers in surface confined coordination networks are able to bind and possibly activate carbon dioxide molecules at low temperatures.

To develop this discovery, we do extensive research on reaction kinetics and dynamics based on molecular level adsorption studies. The prototype system has large potential for further development as active Fe cores (Fe is present in carbon monoxide dehydrogenases in anaerobic bacteria) can be replaced with other metals, e.g., Mg (active metal atom in chlorophyll), Ni or Ti. Besides that, the organic ligand and substrate replacement further alters the properties of the system.