Variable-temperature Scanning Probe Microscope for Ultra-High Vacuum

• Subject Area: Condensed Matter Physics
• Term: Funded in 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 531220212

The research of the group focusses on molecular nanoscience and surface physics of interfaces. The controlled environment of ultra-high vacuum enables the application of highly accurate characterisation methods, which comes at the cost of limitations posed by vacuum sample preparation. Over the last decade, a sophisticated experimental set-up named electrospray controlled ion beam deposition system (ES-CIBD) was developed in-house, which became fully operational recently. With this instrument, one of a small number existing internationally, we could expand the class of molecular systems studied to macromolecular species, which opens previously inaccessible playgrounds in the chemistry and physics of adsorbed functional molecules and their nanoscale assemblies on surfaces. To enable the further development of this novel, highly promising research direction, a dedicated and versatile characterisation tool is requested, namely a variable temperature scanning probe microscope integrating both tunnelling and atomic force (STM and AFM) measurement modes. The main purpose of the requested instrumentation is to be able to provide an optimised work flow for acquisition of (i) high-resolution topographic maps of soft-landed macromolecules (ii) characterisation of the molecular conformation, environment and molecular self-assembly, (iii) electronic maps featuring local contact potential difference or surface density of states and (iv) characterisation of nanomechanical properties and exploration of molecular manipulation protocols. This will be achieved by a combined scanning tunnelling and atomic force microscope. Additionally, the data acquisition at variable temperatures enables to capture dynamic effects, determine the thermal stability of nanoscale organisations, and activation barriers of surface reactions and processes. In this respect, an operational temperature regime of ~ 100 to 400 K is expected to provide adequate versatility to investigate the dynamics of the relevant nanoscale phenomena. Importantly, the AFM capabilities are decisive to explore (ultra-)thin films of macromolecular species and study ES-CIBD preparations on nonconductive substrates, which are frequently of scientific and technological interest or relevance.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Temperaturkontrolliertes Rastersondenmikroskop für Ultrahochvakuum
• Instrumentation Group: 5091 Rasterkraft-Mikroskope
• Applicant Institution: Technische Universität München (TUM)
• Leader: Professor Dr. Johannes V. Barth