Raman fingerprints of ultrasmall nanodiamonds produced from adamantane

A new generation of nanodiamonds produced from hydrocarbons at high pressure has recently expanded the family of bottom-up-synthesis nanodiamonds. The first steps towards characterization of this nanomaterial allow us to suppose that more than one of its remarkable properties and applications will be demonstrated in the coming years. Here we report the Raman features of ultrasmall (2–5 nm) nanodiamonds synthesized purely from adamantane at pressure of 12 GPa. A set of unusual lines with pronounced maxima near 1147, 1245, 1344, and 1456 cm−1 is confidently identified with the bending vibrational modes of CH groups terminating a nanodiamond surface. Excessively intense mode at 1344 cm−1 is explained by its coupling with the 1328 cm−1 diamond phonons. The CH lines observed in the Raman range 1100–1500 cm−1 is proposed to be used for express recognition of ultrasmall nanodiamonds produced from adamantane and other hydrocarbons. Note that such highly hydrogenated nanodiamonds are promising solid-state source of solvated electrons for applications in chemical catalysis and biomedicine. [Display omitted] •Highly hydrogenated nanodiamonds are produced from hydrocarbons.•CH lines are observed in Raman of ultrasmall nanodiamonds.•CH vibrational mode interacts with the diamond phonons.