Formation of diamond-like carbon films and carbon foam by ultrafast laser ablation

The ultra-fast ablation of a graphite target using high repetition rate Nd:YAG lasers allows us to deposit two distinctly different carbonaceous structures, depending on the ambient Ar pressure: a diamond-like carbon film with the surface finish down to atomic level at a pressure below 0.1 Torr, and a fractal C nanofoam with air-like density and diamond-like resistivity at higher pressure. The experimental characterization of vapors and carbonaceous materials produced is presented and compared to the theoretical predictions. The analysis of the formation conditions leads to the qualitative understanding of the formation mechanism for both C structures.