# IR Pulsed Laser Ablation of Carbon Materials in High Vacuum  
[PERSON]  
1 MIFT Department, University di Messina, Viale F.S. d'Alcontres 31, 98166 Messina, Italy;  
lorenzo.  
Depending on its allotropic state, carbon has different chemical and physical properties. For instance, graphite has good electrical conductivity in directions orthogonal to the planes (3 \(\times\) 10\({}^{5}\) S/m \(\perp\) basal plane), while diamond is an insulator with very low electrical conductivity (10\({}^{-11}\) S/m); graphite and amorphous carbon are black and opaque, while diamond is highly transparent. Graphite and vegetable carbon are soft, while diamond is the hardest known material.  
Generally, carbon materials may be chemically resistant and require high temperatures to react even with oxygen. Carbon atoms may form multiple stable covalent bonds with other atoms. Its first four ionization energies of 11.26 eV, 24.38 eV, 47.89 eV, and 64.49 eV are much higher than those of the elements of the same group in the periodic table (Si, Ge, Sn, and Pb) [5]. At very high pressure, carbon forms the more compact allotrope, the diamond, having a density of 3.51 g/cm\({}^{3}\), nearly twice the density of graphite (2.2 g/cm\({}^{3}\)). Carbon may also be present at a very low density, below 1 g/cm\({}^{3}\), as in the case of vegetable carbon (charcoal) used for heating or active carbon used as medicine [6; 7].  
Carbon films, carbon micro- and nanostructures, carbon nanotubes, carbon dots, fullerenes, graphene, and other carbon aggregates are finding important applications in different scientific fields, from physics to biomedicine, from engineering to chemistry, from microelectronics to forensic science [8; 9].  
C-dots are finding many applications for their strong luminescence properties; energetic C ions can be used in radiotherapy; C-nanotubes modify the properties of the polymer and other materials; a diamond can be applied to be used as a radiation detector; graphene oxide can be employed as a dosimeter and to build microelectronic devices; graphite and pyrolytic carbon can be used as biomaterials; and others [10; 11; 12].  
One reliable method to obtain C-thin film deposition, C-nanostructures, small carbon aggregates, carbon nanodimands, carbon ions for ion accelerator sources, C-dots, and others is the pulsed laser ablation (PLA) technique [13]. It is based on the laser irradiation of solid carbon targets placed in air, vacuum, gases, or liquids, resulting in the generation of a plasma at the solid surface, which expands accelerating C atoms, which can produce thin film deposition, C-aggregated, C-dots in liquids, C nanostructures, and others [14].  
The research activity in this field has been developed in the last ten years, investigating the effects of the laser-carbon matter interaction, using different types of lasers and carbon targets, with interaction in a vacuum, in gases and liquids, and comparing obtained results with the literature data [3; 15].  
This work aimed to understand how the energy released by short laser pulses can produce different effects in carbon targets with different allotropic states. To this, an ns pulsed laser at a 1064 nm wavelength is employed to irradiate different types of carbon targets placed in a high vacuum to evaluate the characteristics of the produced plasma, for a better insight into the quality of thin film deposition, its adhesion to the substrate, C-nucleation, and C-dot formation processes [16; 17].  
The presented study finds applications in different fields. Overall, it can be applied to the laser ion sources (LIS) to generate carbon ions in a vacuum for successive acceleration, as presented in the literature [18; 19], or to investigate the ion carbon-nucleation-generating nanoparticles, C-dots and fullerenes, in a vacuum, and in liquids, as presented in the literature [20; 21; 22].