Femtosecond laser carbonization of polystyrene

Multi-pulse femtosecond laser irradiation of a monolayer of polystyrene microspheres deposited on a polystyrene substrate leads to the formation of carbon nanomaterial exhibiting broadband excitation-dependent luminescence both within the microspheres and in the substrate. Initial polystyrene substrate and microspheres are transparent at the laser wavelength (800 nm). Peak intensity of the laser irradiation focusing by the microspheres reaches 1013 W/cm2, resulting in multiphoton absorption followed by ionization and further carbonization processes. Raman spectroscopy and transmission electron microscopy analysis show that carbonization products contain carbon crystalline nanoobjects.