1. National University of Science and Technology MISiS, 4 Leninsky Ave., Moscow 194017, Russia
2. Central Laboratory of Solar Energy and New Energy Sources at the Bulgarian Academy of Science, Blvd. Tzarigradsko Shosee 72, 1784 Sofia, Bulgaria
3. Technological Institute for Superhard and Novel Carbon Materials, 7 Centralnaya St., Troitsk, Moscow 142190, Russia
4. University of Florida, Gainesville, Florida 32611, USA