The goal of this experimental internship is to follow in real time the bond formation of two isolated species initially separated in an ultracold (0.37K) superfluid solvent. For this purpose, we will use ultrashort laser pulses to trigger, track and characterize the reaction following a pump-probe methodology. In practice, we will rely on time-resolved photoionization spectroscopy, a technique based on the ionization of the species by the laser pulses and on the detection of the electrons and ions as molecular probes. The electron carries information about the initial electronic state of the ionized species, while the ion reveals the final state after relaxation processes such as fragmentation or isomerization.