Graphite-diamond phase transition induced by interlayer charge transfer exciton in visible region

A new photoinduced phase with interlayer sigma bonds was experimentally discovered in a graphite crystal. We theoretically study the mechanism of this nonequilibrium phase transition, in terms of the proliferation of photogenerated the Franck-Condon state, the result in electron hole pair is quite unstable, being easily dissipated into the two dimensional (2D) electronic continuum as plus and minus free carriers. However by a small probability, the electron and the hole are bound as an interlayer CT exciton, due to the Coulomb attraction between them. This exciton self-localizes, contracting the interlayer distance and buckling the six membered ring of graphite, only around it. Due to plenty of excitations, interlayer sigma bonds are cooperatively formed, and thus a tiny sp(3) nanoscale domain appears. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim