Overview of project A08

Non-Equilibrium Dynamics of Tunnel Junctions Excited with Terahertz Light


Investigation of individual atoms, molecules, and clusters using scanning tunnelling microscopy has been allowing deep understanding of physical and chemical effects taking place at the atomic scale. Yet, many microscopic processes, such as charge transfer, vibration, and conformational switching of molecules, often take place at timescales that are out-of-reach for conventional microscopes. The coupling of terahertz light to the junction of a scanning tunnelling microscope (THz-STM) appears to solve this issue, with recent demonstrations of a sub-picosecond time resolution on individual molecules. The technique unravels unprecedented investigations of fast processes at the atomic scale. The main goals of the project are a further understanding of the microscopic processes associated with this young technique and the exploration of non-equilibrium dynamics of individual metal clusters and molecules adsorbed on surfaces.

Figure: Illustration of the instrumentation working principle of THz-STM.



Hüseyin Azazoglu, Philip Kapitza, Martin Mittendorff, Rolf Möller and Manuel Gruber
Variable-Temperature Lightwave-Driven Scanning Tunneling Microscope With a Compact, Turn-Key Terahertz Source
Rev. Sci. Instrum. 95, 023703 (2024)
DOI: 10.1063/5.0165719

Hüseyin Azazoglu, Rolf Möller and Manuel Gruber
Thermal Expansion in Photo-Assisted Tunneling: Visible Light versus Free-Space Terahertz Pulses
Surf. Sci. 743, 122465 (2024)
DOI: 10.1016/j.susc.2024.122465



Jan Grunwald, Jorge Torres, Axel Buchholz, Christian Näther, Lea Kämmerer, Manuel Gruber, Sebastian Rohlf, Sangeeta Thakur, Heiko Wende, Winfried Plass, Wolfgang Kuch and Felix Tuczek
Defying the Inverse Energy Gap Law: A Vacuum-Evaporable Fe(ıı) Low-Spin Complex With a Long-Lived LIESST State
Chem. Sci. 26, 7361 (2023)
DOI: 10.1039/d3sc00561e

Chao Li, Roberto Robles, Nicolas Lorente, Sanjoy Kr Mahatha, Sebastian Rohlf, Kai Rossnagel, Alessandro Barla, Boris V. Sorokin, Stefano Rusponi, Philippe Ohresser, Sara Realista, Paulo N. Martinho, Torben Jasper-Toennies, Alexander Weismann, Richard Berndt and Manuel Gruber
Large Orbital Moment of Two Coupled Spin-Half Co Ions in a Complex on Gold
ACS Nano 17, 10608 (2023)
DOI: 10.1021/acsnano.3c01595

Sven Johannsen, Manuel Gruber, Cyrille Barreteau, Maksym Seredyuk, José Antonio Real, Troels Markussen and Richard Berndt
Spin-Crossover and Fragmentation of Fe(neoim)2 on Silver and Gold
J. Phys. Chem. Lett. 14, 7814 (2023)
DOI: 10.1021/acs.jpclett.3c01551

Kira Kolpatzeck, Lothar Brendel, Rolf Möller, Roberto Robles and Nicolás Lorente
Paradoxical Effects for a One-Dimensional Periodic Potential Embedded in a Two-Dimensional System
Phys. Rev. B 107, 155418 (2023)
DOI: 10.1103/PhysRevB.107.155418



Sven Johannsen, Sascha Ossinger, Jan Grunwald, Alexander Herman, Heiko Wende, Felix Tuczek, Manuel Gruber and Richard Berndt
Spin Crossover in a Cobalt Complex on Ag(111)
Angew. Chem. Int. Ed. 61, e202115892 (2022)
DOI: 10.1002/anie.202115892