When a hydrogen or a deuterium atom is interacting with a graphene surface during scattering events, its energy loss determines if the projectile will be adsorbed or scattered. The energy loss highly depends on the initial conditions of the projectile and the surface. Unlike for metal and insulator surfaces, a barrier to C-H bond formation is involved, which is the movement of a single carbon atom out of the surface plane (puckering) and by that rehybridization of the C-atom from sp2 to sp3. In the experiments, a bimodal branching of the translational energy and scattering angle distributio...