Non-thermal ablation of graphite by ultrashort pulsed fs-laser radiation

We will present results of studies on a novel fs-laser induced ablation mechanism, which in literature is denoted as “athermal” or “non-thermal” and includes no melting or evaporation processes. This non-thermal ablation process is capable for solids where the atomic bond strength normal to the surface is significantly different to those in lateral direction. One example for such a solid is given by graphite. In graphite the Carbon atoms of a single graphene layer are bond covalently and thus exhibiting a bond strength of 4 eV per atom. In contrast, the interlayer bond strength normal to the surface results of the more than two orders of magnitude weaker Van-der-Waals-interaction. Without influencing the strong layer internal sp²-bonds this ablation process only breaks the weak van-der-Waals bonds between the layers resulting in a spalation dynamic of the topmost intact graphene layers from the surface of the highly oriented pyrolytic graphite target. Maintaining the internal sp² crystalline structure of the ablated graphene layers this non-thermal ablation process is feasible to transfer thin layer of sandwich structured solids on various substrates, conserving their mechanical and electronic properties.