Pulsed laser ablation from a rotating graphite target operating both in vacuum (~ 10-5 Pa) and in He sustaining gas (~ 10 Pa) has been used to grow thin carbon films on Si< 100> substrates kept at temperatures from RT to 900 C. Synchrotron and laboratory X-ray diffraction (XRD), performed at grazing incidence, established the formation of nano-sized graphene structures at higher deposition temperatures (~ 800÷ 900 C). When the carbon plume was expanding in vacuum, these structures resulted to be formed by few parallel graphene layers, characterised by an oriented growth along the graphene planes, with the axis parallel to the substrate. High resolution (HR) cross section TEM images of C nano-structures on grids or in film/Si substrate confirmed both size and orientation of the graphene nano-particles. The presence of He atmosphere in the reaction chamber changes basically the particle nucleation …