Technion Team Combines Light Pulses and STM to Visualize Electron Dynamics

Researchers from Israel’s Technion, working together, have unveiled a novel method that fuses ultrafast laser pulses with a scanning tunneling microscope (STM), enabling control and detection of electron movement at the level of single atoms.

This advance tackles a persistent problem in condensed‑matter physics: watching an electron move through a solid while also imaging the atomic terrain it occupies. Conventional STM provides sub‑angstrom surface maps but operates too slowly to capture rapid dynamics. In contrast, ultrafast laser spectroscopy records processes on femtosecond timescales but cannot resolve individual atoms. Merging the two techniques, the Technion group attained simultaneous atomic‑level spatial detail and femtosecond‑level temporal manipulation.

The experiment employs a short light flash—just a few tens of femtoseconds long—directed at the STM’s tip‑sample junction. This pulse momentarily alters the electronic potential there, functioning like a gate that can speed up, slow down, or reroute electrons tunneling between tip and sample. The team then measures the tunneling current, which reveals how the electron wave packet reacted to the optical trigger.

First results show that this approach can tune electron transport with a level of precision not previously possible using a single device. Being able to initiate, halt, and guide electrons on femtosecond timescales grants access to core phenomena like charge transfer, surface reactions, and quantum coherence in nanostructures. Additionally, the method offers an experimental testbed for theoretical models of ultrafast electron dynamics that have until now existed only in simulations.

Although the proof‑of‑concept work was performed on uncomplicated metallic surfaces, the scientists point out that the technique can be applied to many other materials such as semiconductors, two‑dimensional crystals, and molecular assemblies. Applying it to more intricate systems could reveal how electrons couple with lattice vibrations, defects, or magnetic textures—insights vital for engineering next‑generation electronic and spintronic components.

This innovation comes as the electronics sector strives for ever‑smaller parts and higher speeds. Grasping electron behavior at the ultimate spatial and temporal limits could guide methods to reduce energy loss, limit heating, and exploit quantum effects in upcoming circuitry.

Looking forward, the group intends to improve the timing alignment between the laser pulses and the STM feedback system, seeking even tighter control over electron injection moments. They also plan to test pump‑probe arrangements that would chart the complete temporal progression of excited electron states. These developments would establish the hybrid apparatus as a flexible instrument for fundamental studies and applied nanotechnology alike.