Graphitization of diamond by laser-accelerated proton beams

In this work, we investigate the interaction between fast energetic proton beams generated by laser-plasma based accelerators with carbon lattices of graphite and diamond. Theoretical and experimental results indicate that these proton beams cause both, a low sputtering of carbon atoms from lattices (estimated to be in the order of 3 x 10(-8) displacements per atom for each single shot), and a heating (inside the target and within a depth of about 10 tm below the surface) at a temperature close to the sp3/sp2 transition. The defects generated inside the lattices by the atom displacements cause the random formation of amorphous carbon islands, while the higher temperature causes the start of diamond partial graphitization. All the results suggest the impossibility to use diamond as detector in laser-driven accelerators when placed close to the source, while they confirm that proton beams can be used as alternative to classical laser or ion beam methods to graphitize diamond in specific optoelectronic applications. (C) 2018 Published by Elsevier Ltd.