HFML-FELIX Laboratory (Nijmegen, the Netherlands)

Stichting Radboud Universiteit, Radboud University, Nijmegen

Radboud University was established in 1923. It has currently seven faculties and enrolls over 20.000 students. It is a student-oriented research university. The Faculty of Science at Radboud University operates the FELIX Laboratory and the High Field Magnet Laboratory (HFML), both open-access, large-scale research infrastructures, and has a number of research facilities such as the NMR laboratory, NanoLab and Trace Gas Facility on campus. The HFML-FELIX Laboratory is scientifically embedded in the Institute for Molecules and Materials and focuses on the development and exploitation of Free Electron Laser sources in the infrared and THz regime. It comprises several research groups with complementary expertise such as (bio)molecular physics, solid state physics and soft condensed matter specialized in research with infrared and THz FEL radiation.

The FEL-based User Facility FELIX provides unique experimental capabilities by its infrared beam lines FLARE, FEL-1 and FEL-2 operating in the wavelength range 3-1500 µm and the intra-cavity laser FELICE operating between 3-100 µm. The FLARE and FELIX beam lines are coupled to 15 user laboratories covering sophisticated instrumentation for experiments in the areas of molecular and biomolecular spectroscopy, cluster sciences, time-resolved spectroscopy, laser spectroscopy. World-unique is the combination of the infrared and THz radiation with the magnets (up to 38 T dc magnetic field) of the HFML.

Research highlights

The institute uses the radiation of free electron laser FELIX to study both static and dynamic properties of matter.

Researchers at HFML-FELIX succeeded in determining the infrared fingerprint for this protonated form (C60 H+). Thanks to new measurements they can now add even more detail to this, which should make it a lot easier to detect the molecule in space.
L. Finazzi, V.J. Esposito, J. Palotás, J. Martens, E. Peeters, J. Cami, G. Berden, and J. Oomens, Experimental Determination of the Unusual CH Stretch Frequency of Protonated Fullerenes, Astrophys. J. 971, 168 (2024).

We reported far-infrared spectrum of isolated neutral S8, under the cold and isolated conditions of a molecular beam. The experimental spectra of the investigated species show a remarkably good agreement with computational modelling, enabling us to predict lower abundance limits for their astronomical detection using the James Webb Space Telescope.
P. Ferrari, G. Berden, B. Redlich, L.B.F.M. Waters & J.M. Bakker, Laboratory infrared spectra and fragmentation chemistry of sulfur allotropes, Nature Commun. 15, 5928 (2024)

In this project we identify the most probable binding position of a vanadium cation on C60 above a pentagon center, demonstrate a high thermal stability for this complex, and explore the bonding nature between C60 and the vanadium cation, revealing that large orbital and electrostatic interactions lie at the origin of the stability of the C60V+ complex. (with users from KU Leuven, Belgium)
J. Xu, J.M. Bakker, O.V. Lushchikova, P. Lievens, E. Janssens, & G.-L. Hou, Pentagon, Hexagon, or Bridge? Identifying the Location of a Single Vanadium Cation on Buckminsterfullerene Surface, J. Am. Chem. Soc. 145, 22243 (2023).

Our team devised a creative approach to switch magnetization, based on the ultrafast analogue of the Barnett effect. Using infrared pulses of light from the free-electron lasers at FELIX, we drive circular vibrations of the substrate lattice. The substrate then becomes magnetic for a few picoseconds, flipping the magnetization of a thin layer mounted on top of it. (with users from Institute for Molecules and Materials, Radboud University)
C.S. Davies, F.G.N. Fennema, A. Tsukamoto, I. Razdolski, A.V. Kimel and A. Kirilyuk, Phononic switching of magnetization by the ultrafast Barnett effect, Nature 628, 540 (2024).

We have recently demonstrated that an ultrafast excitation in the infrared range can induce permanent all-optical reversal of ferroelectric polarization between different stable states. For this we relied on very specific optical properties that naturally emerge from the solid’s ionic lattice resulting in the demonstrated mechanism of reversal being truly universal, capable of permanently switching order parameters in a wide variety of systems.
M. Kwaaitaal, D. G. Lourens, C. S. Davies & A. Kirilyuk, Epsilon-near-zero regime enables permanent ultrafast all-optical reversal of ferroelectric polarization, Nature Photonics 18, 569 (2024).

Expertise

Understanding the perplexing links between the quantum domain of individual atoms and the macroscopic world around us represents a monumental challenge in — but not limited to — physics and chemistry. The research agenda of HFML-FELIX aims to solve these grand challenges by studying fascinating phenomena at the detection and resolution limits available. Harnessing some of the unprecedented wavelength span and pulse energies of the suite of free-electron lasers, also in a combination with the world’s highest continuous magnetic fields are the key to discover, visualise, characterise and comprehend, for example, unidentified molecular structures and novel phases of matter.

The following topics broadly represent the research alignment and starting point of the new institution. This has been defined in close collaboration with the HFML-FELIX research team and the Institute for Molecules and Materials (IMM, Radboud University) and includes the many ongoing collaborations with national partners.

Overview of the research and engineering topic lines

  1. Mapping and manipulating quantum phases of matter  
  2. Non-equilibrium phases of matter
  3. Dynamic self-organisation in soft molecular matter: Fundamental insights from extreme conditions
  4. Molecular structure identification and reactivity using advanced infrared spectroscopy
  5. Innovative instruments for advanced spectroscopy in high magnetic fields and with intense infrared/THz light
Equipment offered to external users

We house a suite of four free-electron lasers that produce (far) infrared light with an unprecedented tuning range and very high intensity. The infrared radiation of the lasers interacts with molecules and materials, which can reveal detailed information about their 3D structure, functional properties, and electronic properties. Cutting-edge research like this contributes significantly to the understanding of new functional materials, (bio)molecules and processes relevant to catalysis and astrochemistry.

In particular, for molecular spectroscopy, a range of mass spectrometers (linear ion traps, Fourier transform ion cyclotron resonance, time-of-flight) is available, equipped with a variety of sources (electrospray, ACPI, laser vaporization, laser desorption, electron impact) that allow the volatilization of virtually any molecular compound, ranging from small molecules in solution to large aromatic and inorganic clusters. Most instruments are operating at room temperature, several allow cryogenic operation down to temperatures of 10 K. Each of these instruments is coupled to the free-electron lasers allowing the most sensitive spectroscopic characterization of analytes under study.

For condensed matter physics direction, ultrafast spectroscopic techniques are available, including both single-colour and two-colour pump-probe techniques, with the possibilities of applying low temperatures and high magnetic fields. Visible femtosecond-range lasers are synchronized to the FELs, allowing for time resolution down to sub-picosecond range.