CEA

The recent development of broadband coherent extreme ultraviolet sources makes it possible to measure dynamics with attosecond resolution (1 attosecond = 10-18 s). This time scale is associated with the electron dynamics and more particularly to the electronic correlation in various systems, from atoms and molecules to solids. Generating and controlling processes on this time scale then gives the opportunity to develop new promising applications in chemistry and biology that can have high impact in society. TD-PICO-MF aims at studying electronic correlation through the measurement of the photoemission delay of core-orbital electrons in a laser-controlled molecular system. For this purpose, TD-PICO-MF brings together advanced technologies from the attosecond interferometry field and laser-induced alignment field, in order to resolve both spatially and temporally the photoemission process. In particular, the research project proposes to study, as a prototype, the photoemission from the 4d core-orbitals of the iodine atom in iodine monochloride (ICl) molecules in gas phase. The measurements will be realized during different laser controlled configurations of the molecular system e.g., during its alignment, orientation and dissociation. The expected impact is to gain a global picture of the influence of the molecular cationic potential during a chemical reaction and to evidence the role of electronic correlation through the measurement of 3D-scattering phase maps in the molecular frame. TD-PICO-MF will utilize existing, and forge new, international collaborations between experiment, theory and academia in order to tackle this complex problematic. The results of our work will be made globally available and presented to the general public. The post doctoral fellow will bring to the host his expertise on laser control of molecular systems and will be trained to the attosecond science and technologies, enlarging his scientific experience and employability.

Star formation is a fundamental process in astrophysics, which has been studied for decades. As of now, most of our knowledge is concentrated on the formation of stars of a few solar masses. If galaxies' total stellar mass is dominated by low-mass stars, their energy budget is exclusively controlled by the enormous luminosity and powerful feedback of massive stars (M > 8 Msun). Despite their importance, the mechanisms leading to the formation of high-mass stars remain a mystery in many aspects. From the theoretical point of view, low-mass star formation models are not directly transposable as they do not provide accretion rates in line with what is necessary for high-mass star formation. From the observational point of view, until the recent rise of large interferometers, little was known about the formation of massive stars due to their scarcity, and remoteness. Through my work with interferometers, I have proved that very dynamical processes (colliding flows) are at play in high-mass star-forming regions (HMSFR). On the other hand, recent studies have shown that magnetic fields are a key factor in the regulation of star-formation. I am convinced that the dynamical features observed in HMSFR coupled with the action of the magnetic fields could explain for the formation of high-mass stars. For this two-year project, I plan on studying the coupling of gas dynamics with magnetic fields. For this purpose, I present an innovative project that will study this coupling simultaneously from observational and numerical inquiries. I will use today's best instrument in radio-astronomy, ALMA, to trace both the kinematics of gas and the magnetic field morphology. This observational part relies on data that I have already acquired. For the numerical part, I will participate in the development of dedicated magneto-hydro-dynamical simulations together with P. Hennebelle to understand the physical processes that underlie the observational features.