The project aims to carry out concerted measurements during the birth of single, growing nuclei using complementary spectroscopic techniques.
 This requires preparing a common and transportable sample device with temperature control and embedded optical fiber for the on-demand production of single-crystal seed. The device will then be used on different microscopic / spectroscopic setups on the Paris-Saclay campus. A switchable focused laser beam will be used to locally trigger the nucleation. The growing crystal seed will be embedded in the microfluidic flow providing a submillisecond resolution thanks to the relation between the position in the flow and the age of the crystal. The perovskite PbMABr3 (MA =  methylammonium) in the organic solvent DMF will be the chemical model system. Its laserinduced crystallization has been reported and reproduced by the LuMIn team. Local heating triggers this crystallization. At PPSM, we shall measure the heating induced by the laser and possibly the resulting shock wave by monitoring the thermal lens using holography. At LuMIn, we shall film the birth of the crystalline phase using fluorescence lifetime imaging (FLIM), monitoring the density of defects in the growing crystals. At SATIE, the size and the growth of the nuclei will be monitored through their Brownian motion in correlation with their fluorescence spectra. SPMS will co-design laser-induced nucleation. Post-mortem characterizations will be performed at the Centre de diffraction of SPMS and with Raman.