Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 40: Ultrafast electron dynamics at surface and interfaces – Poster (joint session O/TT)

O 40.8: Poster

Dienstag, 10. März 2026, 14:00–16:00, P2

First steps with a qPlus-based MIR AFM — •Furkan Özyigit, Lukas Böhm, Leonie Weiß, Jay Weymouth, Rupert Huber, and Franz Gießibl — University of Regensburg, 93053 Regensburg

We report initial progress in an ultrafast non-contact atomic force microscope/scanning tunneling microscope (NC-AFM/STM) platform based on qPlus sensors, integrated with a CEP-stabilized mid-infrared (MIR) pump-probe system and tunable optical parametric amplifier (OPA) for versatile excitation. In first experiments, we successfully induced transient tunneling currents on Cu(111) using MIR pulses, demonstrating precise control of ultrafast electronic excitation at the atomic scale via laser-coupled tunneling. While the tunneling cur- rent reflects the ultrafast electronic excitation dynamics, the qPlus sensor permits complementary force detection to monitor subsequent structural or electrostatic interaction changes, such as those resulting from induced charge redistribution or lattice relaxation. This enables simultaneous probing of electronic and mechanical dynamics with fem- tosecond time and sub-nanometer spatial resolution. Beyond investi- gations of transient electrostatic forces, this versatile system facilitates a broad class of ultrafast nanoscale experiments, including scattering- type scanning near-field optical microscopy (s-SNOM) for imaging car- rier and phase dynamics, time-resolved tip-enhanced spectroscopy for molecular states, and pump-probe tunneling spectroscopy.

Keywords: Ultrafast; Laser; MIR; qPlus; AFM