For photosynthetic organisms, light is of major importance as it represents not only the main source of energy for metabolism, but also a very informative cue about their surroundings. A recent study has shown that diatoms, a prominent phytoplanktonic group of microalgae, use phytochrome (DPH) photoreceptors to acclimate their photosynthesis performance according to depth. Current knowledge about photoconversion mechanism of phytochromes has been acquired from plants and bacteria. Unravelling biophysical properties of photoswitching yield and photodynamics in DPH will provide novel information about the molecular basis of light sensing in phytochromes photoreceptor family and the specific adaptations of light-sensing mechanisms in marine organisms. The study of Diatom phytochrome is an ANR funded project, D-Phyto, that involves M. Sliwa and the group Internal dynamics of biomolecules @ LOB (Ecole Polytechnique) The M2 internship will focus on the characterization of new DPHs. The internship will include being tutored on and gaining hands-on experience in multi-time scale transient absorption visible spectroscopy with the access to a new platform developed by the team, in data-analysis, and characterization of multiscale photodynamics. Depending on the candidate profile, the implementation of a new laser system may be considered.