Correlation Induced Relaxation dynamics in Complex XUV-Excited molecules – CIRCE

The goal of the CIRCÉ project is to exploit the opportunities offered by ultrashort extreme ultraviolet (XUV) pulses to investigate the role played by the many-body nature of the molecular wavefunction on the stability of large carbon based systems. We will explore how the absorption of a single energetic XUV photon initiates an electronic excitation that may involve several electrons (due to electron correlation), and how this excitation induces ultrafast processes and energy flow in large molecules that engage couplings between electronic and vibrational degrees of freedom (i.e involving non Born-Oppenheimer couplings). Recent seminal experiments have demonstrated the importance of XUV-induced charge dynamics and energy flow in small di /tri-atomic molecules and managed to measure femtosecond (1fs = 10-15 s) or even attosecond (1 as = 10-18 s) processes (see review article: F. Lépine et al. Nature photonics 8, 195-204 (2014)). The extension of this type of experiment to larger molecules is crucial for the future of the field and to impact other scientific communities. It challenges both current experimental and theoretical capabilities.
Our research program will tackle the, so far, largely unexplored case of XUV induced ultrafast mechanisms in large systems composed of several tens of atoms. In CIRCÉ, we will study carbon based molecules such as the polycyclic aromatic hydrocarbons molecules (PAH) and fullerenes (C60). These systems have ideal physical and chemical properties for our research program with, for instance, strong correlation effects in photoionization in the VUV-XUV spectral domain. They are also relevant in other research fields such as astrochemistry and photovoltaics. We will use time-resolved mass-spectrometry (M.S) and time resolved velocity map imaging spectrometry (VMIS) to investigate electronic excitation and non-adiabatic relaxation in these highly excited molecules using a state-of-the-art tunable XUV source. We will also foster the development of the next generation of XUV physics experiments in complex molecules aiming for unprecedented control of these pulses and reaching attosecond precision. This would allow the study of coherent charge dynamics on few femtosecond timescale. This will be done in CIRCÉ by exploring new approaches for ultimate precision and control of XUV light pulses. We will also push our understanding of XUV induced processes on the quantum level by using many-body quantum theories to enlighten and disentangle the role of the interaction between microscopic constituents of molecules.
This frontiers research program is highly demanding experimentally on XUV sources, molecular spectroscopy and on ultrafast many-body simulations on the theory side. Our approach in CIRCÉ consists in merging specialists of ultrafast molecular spectroscopy (ILM), of ultrashort XUV pulse sources (CELIA) and theoreticians of the many-body approach in light-complex molecule interaction (LPT). Moreover, CIRCÉ will also benefit from well-established collaborations with world-known experts of multielectronic and non Born-Oppenheimer theories (e.g, Prof. A. Kuleff and Heidelberg group) and worldwide-recognized specialists of astrochemistry (e.g, Prof. A. Tielens (Leiden university)), in order to develop an effective connection between our research program and its implication in other research fields.