LACUS (Lausanne, Switzerland)
Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne Centre for Ultrafast Science
The LACUS facility offers a broad spectrum of advanced ultrafast methods to study the interaction of complex materials and nanostructures with light. This is a key aspect for developing novel functional materials, with a special focus on photonics applications. LACUS is one of the first European user-access facilities combining probes sensitive to the lattice structure, such as electron diffraction and microscopy, with probes for electronic structure of material such as angle-resolved photoelectron spectroscopy and ultrafast optical spectroscopy. This enables a complete picture of how materials interact with light and will offer to users the possibility of combined experiments where multiple complex experimental techniques are used, combining nanometric spatial resolution and femtosecond temporal resolution. The LACUS facility is located at the EPFL campus and collaborates in an institute’s network of facilities for crystal growth and characterization, advanced electron microscopy and sample preparation, and clean rooms with processing equipment for nanotechnology. This allows for complex sample preparation procedures attractive for the material science community.
Website: www.epfl.ch/research/domains/lacus/
Contact:
Fabrizio Carbone
Michele Puppin
Research highlights
The research performed with the instruments at the facility covers a broad range of topics, reflecting the rich offer of setups. It ranges from materials science topics, such as measuring the electronic structure and photocarrier dynamics of solar materials by trARPES (10.1021/acs.nanolett.1c03941), the study of ultrafast structural phase transitions by UED (10.48550/arXiv.2210.00070) or the ability of coherently controlling magnetic excitation such as skyrmions by light in cryo-Lorentz electron microscopy (10.1103/PhysRevX.12.041030). The generation and characterizazion of electron vortex beams in an ultrafast TEM demonstrates the capability of studying electron beam interactions with plasmonic near fields and the nanoscale. Finally from the chemical physics side, ultrafast optical experiments in iron-based complexes are showcased by the achievement of chiral control of the dynamics of spin crossover compounds (10.1038/s41557-022-00933-0).
Expertise
Non-collinear optical parametric amplifier for transient absorption spectroscopy, C EPFL 2021
The Lausanne Centre for Ultrafast Science (LACUS) is a university platform providing user access to ultrafast photon and electron spectroscopies. We have expertise in:
- Time- and Angle-resolved Photoelectron spectroscopy
- Ultrafast UV-VIS optical spectrocopy
- Ultrafast electron diffraction
- Ultrafast trasmission electron microscopy, lorenz microscopy, momentum-resolved energy loss spectroscopy
Equipment offered to external users
The Harmonium beamline laser system, C EPFL 2021
A total of 6 ultrafast amplified laser sources are present in the facility, used for multiple spectroscopies on condensed matter and molecular systems.
- High-harmonic generation beamline with a time-preserving monochromator, equipped with a trARPES end station, and a free end station for custom XUV light scattering experiments. Two independent XUV sources can be used for trARPES: Harmonium (6 kHz, 15-100 eV) and Yperion (1 MHz, 9-11 eV), accessing in the time domain band structure dynamics with tuneable energy-time resolution.
- Utrafast electron diffractometer, both for reflection and transmission electron diffraction. The machine is equipped with a state-of-the-art hybrid pixel electron detector, enhancing the sensitivity of the machine for pump probe lattice diffraction and phonon dynamics studies by thermal diffuse scattering. The same laboratory hosts transient UV-VIS absorption or reflectivity setups, equipped with a cryostat and a high-speed detection system.
- Utrafast transmission electron microscope with an electron energy loss spectrometer, recently upgraded with a novel hybrid pixel detector. This unique combination allows to study ultrafast electron-photon interactions in nanostructured materials and is furthermore capable of cryo-Lorentz microscopy of magnetic materials.