Photo-exfoliation of graphene from graphite: An {\em ab initio} study

Mass production of high-quality graphene monolayers is an essential prerequisite for producing graphene devices [1]. Flaws of current synthesis techniques, such as chemical exfoliation combined with sonication[2] are remaining contaminants, and CVD synthesis [3] suffers from the influence of the substrate [3]. The best quality graphene monolayers are still obtained using the scotch-tape technique [1], which is ill-suited for mass production. By performing {\em ab initio} TDDFT-MD calculations, we have identified irradiation by ultra-short laser pulses as a suitable technique to produce graphene monolayers by photo-exfoliating graphite without the above drawbacks. Our simulations indicate that exposing graphite to 800~nm laser pulses with a suitable pulse shape and intensity may cause detachment of single graphene layers due to a non-equilibrium charge redistribution in a vibrationally cold substrate [4] \newline [1] K. S. Novoselov {\em et al.}, Science {\bf 306}, 666 (2004), and supporting mat. \newline [2] X. Li {\em et al.}, Science {\bf 319}, 1229 (2008). \newline [3] A. Reina {\em et al.}, Nano Lett. {\bf 9}, 30 (2008); X. Li {\em et al.}, Science {\bf 324}, 1312 (2009). \newline [4] Y. Miyamoto, H. Zhang, and D. Tom\'anek, submitted.