We aim at measuring ultrafast processes in atoms, molecules, and solids using innovative spectroscopic techniques based on high-order harmonics, strong-field driven attosecond electron wavepackets, XUV angle-resolved photoemission spectroscopy, as well as fs-REMPI (resonant enhanced multiphoton ionization) using velocity map imaging, COLTRIMS, and Momentum microscopy detection schemes. These research interests lead us to develop theoretical tools to describe the main steps of undergoing pump-probe experiments.
The HarMoDyn team is located in the laboratory CEntre Lasers Intenses et Applications (CELIA - CNRS UMR 5107) at Universite de Bordeaux, 351 Cours de la Libération, 33405 TALENCE CEDEX, France.
CELIA facilities are accessible through the national LOA-LIDYL-CELIA call, and via LASERLAB Europe.
One of our main research interests is the investigation of ultrafast dynamics of chiral molecules in the gas phase, on the femtosecond and attosecond timescale. This is the goal of the EXCITERS project - Extreme Ultraviolet Circular Time-Resolved Spectroscopy - funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program. This project aims at developing innovative tools based on high-repetition-rate fiber laser systems, coincidence electron-ion imaging, and high harmonic spectroscopy, to study chiral molecules.
One of our main research interests is the investigation of ultrafast light-induced dynamics in quantum materials using time-, angle-, and polarization-resolved photoemission spectroscopy. This is the goal of the UTOPIQ project - Ultrafast Topological Engineering of Quantum Materials - funded by the European Research Council (ERC) Starting Grant (StG). This project aims at developing innovative measurement protocols in multidimensional photoemission spectroscopy to probe ultrafast out-of-equilibrium topological phase transitions in two-dimensional quantum materials.
Electrons filming themselves
Strong laser fields enable taking snapshots of a molecule using its own electrons. The electrons are ionized from the molecule, accelerated by the laser field and driven back to recombine with their parent ion, emitting a flash of light which encodes the molecular structure. We have performed an experiment in which two consecutive sets of electrons probe the same molecule, providing two snapshots separated by a few hundreds attoseconds. Comparing these two snapshots reveals the dynamics of the molecule in the strong laser field.
Viewpoint in Physics:
Electrons on the run
Will an electron escaping a molecule through a quantum tunnel behave differently depending on the left- or right-handedness of the molecule?
Revealing the Influence of Molecular Chirality on Tunnel-Ionization Dynamics, E. Bloch et al. Phys. Rev. X 11, 041056
A new observable in ARPES
We introduced a novel measurement methodology and associated observable in extreme ultraviolet (XUV) angle-resolved photoemission spectroscopy (ARPES), based on continuous modulation of the ionizing radiation polarization axis. Tracking the energy- and momentum-resolved amplitude and phase of the photoemission intensity modulation upon polarization axis rotation allows us to retrieve the circular dichroism in photoelectron angular distributions (CDAD) without using circular photons, providing direct insights into the phase of photoemission matrix elements.
Polarization-modulated angle-resolved photoemission spectroscopy: Toward circular dichroism without circular photons and Bloch wave-function reconstruction, Michael Schüler, Tommaso Pincelli, Shuo Dong, Thomas P Devereaux, Martin Wolf, Laurenz Rettig, Ralph Ernstorfer, Samuel Beaulieu, Physical Review X 12 (1), 011019 (2022)
Photoelectron Elliptical Dichroism Spectroscopy
When chiral molecules are ionized by elliptically polarized laser pulses, a strong forward/backward asymmetry appears in the angular distribution of the photoelectrons. In this recent article published in PCCP, we use this PhotoElectron Elliptical Dichroism (PEELD) as a spectroscopic tool to investigate the influence of different Rydberg states in the resonance-enhanced multiphoton ionization of fenchone by tunable femtosecond pulses.
Physics Focus: Molecular Probe Uses a Polarization Flip
Read an article on Physics describing our recent results on shaping the sub-cycle optical chirality of a laser field to probe molecular chirality:
Focus: Molecular Probe Uses a Polarization FlipFocus: Molecular Probe Uses a Polarization Flip
The results are published in Physical Review X:
Controlling Subcycle Optical Chirality in the Photoionization of Chiral Molecules,
S. Rozen, A. Comby, E. Bloch, S. Beauvarlet, D. Descamps, B. Fabre, S. Petit, V. Blanchet, B. Pons, N. Dudovich, and Y. Mairesse, Phys. Rev. X 9, 031004 (2019)