Structural Characterization of Ionized Species
Debora Scuderi (Prof), Philippe Maitre (Senior Researcher), Nicolas Jestin (Assistant Engineer), Romaric Lenk (CNRS Research Engineer), Francis Berthias (Postdoc), Eskander Alhajji (Long-term Visitor)
Alumni: Chiraz El Saddik (PhD), Yining Jiang (PhD), Yali Wang (PhD)
Action spectroscopy is a key method for the structural characterization of ionized species. When a tunable source like the infrared free-electron laser (CLIO) is used, this technique provides detailed information about the structure of ions. Over the years, this methodology has been refined by coupling IR and UV lasers with both high and low mass-resolution ion traps (FTICR and Paul Trap), offering a powerful tool that is uniquely accessible worldwide in Orsay (CLIO) or Nijmegen (FELIX).
The SMAS/CLIO platform has been a user facility within the CNRS Research Infrastructure Infranalytics since January 2022, and it joined the Operando-Prototyping platform of the PEPR LUMA in January 2024.
A new klystron was acquired in 2022 and delivered in 2023. Its installation was completed in July 2024. The restart of the free-electron laser is underway, and user operations are expected to resume in January 2025.

The CLIO accelerator undulator where the tunable laser beam is generated.
The team has developed particular expertise in the spectroscopic characterization of post-transcriptional modifications, in collaboration with Professor M.-E. Crestoni’s group in Rome. This collaboration has led to significant advances in the study of biological molecules and drugs used in cancer treatments, such as Cisplatin.
The group has conducted notable research on various topics, including:
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- Post-translational modification studies [Maitre2020]
- Characterization of oxidation processes under oxidative stress [Jiang2023], in collaboration with the TheoSim group (C. Clavaguera) and CPSysBio (C. Houée-Levin)
- Monitoring of catalytic or reactive processes [Scuderi2020]
- Assessment of chiral and structural effects in molecular assemblies [BenNasr2019]
- Characterization of organometallic complexes and nanostructures
- Reconstruction of the IR spectrum of a peptide based on representative conformers [Kotobi2023]
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Collaborations
Chantal Houée-Levin (CPSysBio, ICP), Carine Clavaguéra (TheoSim, ICP), Maria-Elisa Crestoni (Sapienza University, Rome, Italy), Lucas Schwob (DESY, Hamburg, Germany), Charles Desfrancois and Nicolas Nieuwjaer (Laboratoire de Physique des Lasers, Sorbonne Paris Nord), Ricardo Spezia (LCT, Sorbonne University).