“…At the first stage, the growth of diamond particles (diamond core) of about 800-1100 nm in size was carried out, during which doping with boron occurred by introducing diborane (B 2 H 6 ) into the gas mixture. The boron-doped nanodiamonds (BNDs), used as the cores, were synthesized by the HFCVD method with parameters we previously determined [23]. Briefly, the substrate temperature was 800 • C, the temperature of the tungsten coil was 2000-2200 • C, the pressure in the reactor chamber was 48 Torr, the hydrogen flow rate was 480 sccm, the methane concentration was 4%, and the growth time was about 3 h. For the synthesis of highly absorbing BNDs, the ratio of boron atoms to carbon atoms (B/C) in the diborane-methane mixture was 64,000 ppm.…”