Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 5: Scanning Probe Microscopy: Light-Matter Interactions at the Atomic Scale I

O 5.4: Vortrag

Montag, 17. März 2025, 11:15–11:30, H6

Triggering chemical reactions in single molecules with ultrashort THz pulses — •Niklas Friedrich, Carmen Roelcke, Tzu-Chao Hung, Yaroslav Gerasimenko, Rupert Huber, and Jascha Repp — Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany

In lightwave-driven scanning tunnelling microscopy (LW-STM), the electric-field transient of ultrashort laser pulses focused into the junction of a tunnelling microscope acts as a bias-voltage transient and thereby controls tunnelling on ultrashort timescales. This allows unravelling the dynamics of quantum systems in pump-probe experiments with atomic spatial and femtosecond temporal resolution [1].

Here, we show that LW-STM can be used to trigger chemical reactions on ultrashort timescales. We study free-base naphthalocyanine molecules (H2Nc) on 2ML NaCl on Cu(111). In DC-biased experiments, this system switches between different tautomers upon injection of high-energy tunnelling electrons [2]. We find that the same reaction is facilitated by ultrashort voltage transients in LW-STM for transients far exceeding the voltage of the lowest unoccupied molecular orbital. Furthermore, even a stepwise deprotonation of the molecule is activated by the ultrashort laser pulses when increasing the voltage transient beyond a threshold value.

[1] Roelcke et al. Nat. Photon. 18, 595-602 (2024) [2] Liljeroth et al. Science 317, 1203-1206 (2007)

Keywords: lightwave-driven STM (LW-STM); ultrashort; scanning tunnelling microscopy (STM); single molecule