Dynamics and Interactions: Radiation, Atoms and Molecules (DIRAM)

Group leader : Eric CHARRON
Institut des Sciences Moléculaires d'Orsay
The DIRAM group currently gathers 9 permanent researchers and 5 PhD students, both experimentalists and theoreticians. Its research activity focuses on the investigation of fundamental processes and related dynamics in the interaction of radiation with matter.

The processes, which are investigated, cover radiation-induced excitation, ionization and / or dissociation in atoms, ions or molecules, primarily in gas phase and in various irradiation regimes. In particular the interaction with intense (10 to 100 TW/cm2, 1TW = 1012W) and ultrashort (femtoseconds to attoseconds, 1 as = 10-18 s) laser pulses provides access to fundamental mechanisms used in the interpretation and control of the dynamics of electrons and nuclei. These fundamental studies are important for many applications, among which molecular imaging techniques, or the production of new laser sources.

Collective effects, correlations and the role of the environment on the dynamics of various fundamental quantum systems are also part of our current research on nano-physics, quantum optics and quantum information.

Radiation in the X-ray and XUV range are the core of our experimental studies, which are performed at specific user facilities such as the SOLEIL-synchrotron facility, the high-order harmonic sources of CEA-Saclay, the plasma-based XUV lasers of LASERIX and LOA, or the X free-electron laser (FEL) facilities (such as FERMI-Elettra in Italy). These experiments are based on innovative methods and advanced (often unique) instruments, which are used to extract accurate data on fundamental processes, such as: coincidence momentum spectroscopy for the study of molecular dissociative photoionization or multiple photoionization, ECR (electron cyclotron resonance) ion sources for the measurement of absolute photoionization cross sections in multiply charged ions, XUV interferometry for the study of the spectro-temporal properties of XUV lasers.