The central objective of this internship is to establish a reproducible route for fabricating europium molecular membranes and, crucially, to determine whether their exceptional optical properties are preserved after exfoliation and transfer. The student will optimize the mechanical exfoliation conditions to increase the yield of thin, large-area flakes; develop deterministic dry-transfer protocols onto photonic substrates such as SiC, SiO2/Si and glass; characterize membrane thickness, morphology and crystalline quality using optical interference microscopy, atomic force microscopy and Raman spectroscopy; and investigate their luminescence and optical homogeneous linewidths at cryogenic temperatures using spectral hole burning. Comparison with bulk crystals will allow the influence of exfoliation, reduced thickness and substrate coupling on the optical coherence of the molecular material to be established.