PhD Position: Fast Atom Interactions with Two-dimensional Materials

in close collaboration with the experimental team at the Catholic University of Leuven in Belgium, ensuring a continuous exchange between model predictions and their experimental validation.

The IPCMS laboratory is located on the Cronenbourg campus, which is easily accessible by public transportation (tram and bus) as well as via the Eurométropole's bike paths. The campus offers a pleasant work environment that includes a university cafeteria and sports facilities.

In a recent article published in Physical Review Letters (Phys. Rev. Lett. 135, 263403 (2025)) and highlighted by the journal editors for its exceptional originality (DOI: 10.1103/Physics.18.s166), we developed a novel spectroscopic technique capable of probing atom–surface interactions with unprecedented precision.

In this combined theoretical and experimental study, a beam of fast hydrogen atoms was transmitted through a graphene sheet, a two-dimensional material consisting of a single layer of carbon atoms arranged in a hexagonal lattice. As the atoms traversed this ultrathin membrane—or, more precisely, as their associated matter waves propagated through it—they generated diffraction patterns analogous to the interference patterns produced when light passes through an optical grating. These diffraction images directly reveal the structural quality, crystallinity, and purity of the graphene while simultaneously providing quantitative information about the interaction between hydrogen atoms and the surface.

Interpreting the experimental observations required a detailed comparison with theoretical calculations describing the atom–surface interaction potential. Only state-of-the-art quantum mechanical simulations based on density functional theory (DFT) were able to quantitatively reproduce the experimental results. This excellent agreement demonstrates the remarkable sensitivity of the technique, which is capable of detecting extremely subtle variations in atom–surface interactions. Beyond its fundamental interest, this approach opens a new avenue for probing materials at the atomic scale using neutral atoms rather than charged particles such as electrons, with the major advantage of causing only minimal perturbation to the systems under investigation.

Building on these results, the proposed Ph.D. project aims to develop the theoretical tools required to investigate other two-dimensional insulating materials in close collaboration with the experimental group of Xavier Urbain (Université catholique de Louvain, Belgium) and with Raj Sinha-Roy (Université Claude Bernard Lyon 1) on the theoretical and numerical simulation aspects. The objective is to analyze how both the nature of the material and the choice of incident projectile (beyond hydrogen) influence the diffraction patterns, thereby providing highly accurate information on atom–surface interaction potentials. Particular attention will also be devoted to inelastic processes, which will be investigated using time-dependent density functional theory (TDDFT). This work will pave the way toward a more comprehensive understanding of the interaction mechanisms between fast atoms and two-dimensional materials.