Development and Application of Ultrafast Low-Energy Electron Microscopy

Project Information

ULEEM

Grant agreement ID: 101055435

DOI

10.3030/101055435

EC signature date 6 May 2022

Start date 1 September 2022

End date 31 August 2027

Funded under

• European Research Council (ERC)

Total cost

€ 2 488 216,00

EU contribution

€ 2 488 216,00

Coordinated by

MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV
Germany

Periodic Reporting for period 1 - ULEEM (Development and Application of Ultrafast Low-Energy Electron Microscopy)

Reporting period: 2022-09-01 to 2025-02-28

Summary of the context and overall objectives of the project

Surfaces are central to many technological applications, including microelectronics and catalysis, but their rapid structural changes have remained difficult to observe directly. The ULEEM project introduces a new method for studying such dynamics by combining laser-triggered electron beams with a Low-Energy Electron Microscope (LEEM). This integration enables time-resolved measurements of structural processes at the nanoscale with high surface sensitivity.

The approach allows for direct observations of how materials respond to external stimuli, such as laser excitation, on ultrafast timescales. This capability is expected to improve our understanding of surface interactions and contribute to advances in materials design, electronic device functionality, and energy conversion technologies.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project has made significant progress in both technology development and scientific discovery:

Technological breakthroughs: The team successfully integrated ultrashort electron pulses into a LEEM setup, and achieved new imaging and diffraction capabilities.
Scientific achievements: The first-ever ultrafast real-space movies of surface-sensitive structural changes were recently recorded (Otto et al., 2025, in preparation), revealing strain wave dynamics and lattice heating in layered materials. These findings will advance our understanding of surface dynamics.
Methodological advances: In order to establish further possibility in ULEEM, new techniques, such as ultrafast low-energy electron diffuse scattering (Kurtz et al., Nature Materials, 2024) and polarization-controlled of a phase transformation (Boeckmann et al., Nature Physics, 2025, were recently introduced, opening doors for further exploration of light-controlled electronic phases at surfaces.
These accomplishments highlight the potential of ULEEM to broadly impact surface science and ultrafast phenomena.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The ULEEM project is delivering tools and methods that are adding a new dimension to ultrafast surface science:

Results: Novel techniques like ultrafast microscopy and scattering provide detailed insights into processes like energy transfer, structural transitions, and vibrational dynamics with at the nanoscale and with ultimate surface sensitivity.
Impacts: These findings hold promise for breakthroughs in understanding microscopic energy-conversion and equilibration processes, with potential applications in enhancing nanoelectronics and materials science.
Future directions: To maximize the potential of the ULEEM approach, further research will explore the various imaging, diffraction and spectroscopy modalities, applied to low-dimensional materials and heterostructures.

The project promises significant advancements in fundamental condensed solid-state physics and materials science, addressing challenges in both academia and potential commercialization. A patent application has been filed.