Low temperature ultrahigh vacuum scanning tunneling/ atomic force microscope with tuning fork sensor

• Subject Area: Condensed Matter Physics
• Term: Funded in 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 493870016

In the frame of the LOEWE Schwerpunkt „PriOSS – Principles of On-Surface Synbthesis“ the reactions of organic molecules on surface will be investigated. An essential technique for these investigations is imaging the molecules with an atomic force microscope, which, under certain conditions, allows the visualization of individual chemical bonds, inter- as well as intra-molecular. For this a scanning atomic force microscope with tuning fork sensor is suitable, working at 5 K in ultrahigh vacuum. The key for this extremely good resolution is functionalization of the probing tip with a carbon monoxide molecule, which is usually picked-up with the tip from the surface before the high resolution scan. Both, the process of the tip functionalization as well as the high resolution imaging of the molecules only work at sample temperatures at low cryogenic temperatures around 5 K. Furthermore, the scan process must be controlled by a very flexible, programmable electronic system, in order to be able to visualize 3-dimensional structures, also called 3D spectroscopy. A further important feature in the frame of the PriOSS projects is the simultaneous excitation of different harmonic oscillation of the sensor beam. These multi-frequency methods allow the (almost) independent but simultaneous recording of different force signals, which enables novel scanning procedures and gives deeper insight into the molecular force interactions. Very important are temperature and drift stability, in order to be able to perform long time scale measurements on molecules. The control electronics must be programmable, and allow for complex 3D spectroscopy measurements.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Tieftemperatur UHV Rastertunnel-/Rasterkraftmikroskop
• Instrumentation Group: 5091 Rasterkraft-Mikroskope
• Applicant Institution: Justus-Liebig-Universität Gießen
• Leader: Professor Dr. André Schirmeisen