Technion Team Combines Light Pulses and Scanning Tunneling Microscopy to Visualize Electron Dynamics

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

This advance tackles a persistent problem in condensed‑matter physics: seeing an electron move through a substance while at the same time imaging the atomic terrain it occupies. Conventional STM provides sub‑angstrom topographic maps but operates with comparatively sluggish temporal resolution. In contrast, ultrafast laser spectroscopy records phenomena occurring in femtoseconds, though it cannot resolve individual atoms. Merging these techniques, the Technion group attained atomic‑scale spatial detail together with femtosecond‑level temporal manipulation.

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

Early data show that the approach can adjust electron flow with a level of precision not previously possible using a single device. Being able to initiate, halt, and direct electrons within femtosecond intervals grants access to core phenomena like charge transfer, surface reactions, and quantum coherence in nanostructures. Additionally, the method offers a hands‑on experimental testbed for theoretical models of ultrafast electron dynamics that have until now existed only in simulations.

Although the proof‑of‑concept work was carried out on straightforward metallic surfaces, the scientists point out that the technique can be readily applied to many other materials such as semiconductors, two‑dimensional crystals, and molecular assemblies. Applying it to more intricate systems could shed light on electron interactions with lattice vibrations, defects, or magnetic textures—knowledge essential for engineering next‑generation electronic and spintronic components.

This innovation comes as the electronics sector strives for ever‑smaller parts and higher operating speeds. Grasping electron behavior at the joint extremes of spatial and temporal resolution could guide approaches to reduce energy loss, limit heating, and exploit quantum effects in upcoming circuits.

Future work will focus on improving the synchronization between the laser pulses and the STM feedback loop, seeking even tighter control over electron‑injection timing. The researchers also plan to investigate pump‑probe schemes that could chart the complete temporal progression of electron states following excitation. These developments would solidify the hybrid apparatus as a flexible instrument for fundamental studies and practical nanotechnology.