Raman fingerprints of ultrasmall nanodiamonds produced from adamantane

TL;DR

This study reports the synthesis of ultrasmall nanodiamonds from adamantane at high pressure and identifies unique Raman spectral features that can be used for rapid detection and sensing applications.

Contribution

It introduces a novel synthesis method for ultrasmall nanodiamonds from adamantane and characterizes their Raman fingerprints for potential sensing uses.

Findings

Distinct Raman bands at 1147, 1245, 1344, and 1456 cm-1 identified.

Raman band at 1344 cm-1 linked to coupling with diamond phonons.

Potential use of Raman signatures for nanodiamond detection and sensing.

Abstract

The synthesis of ultrasmall (2-5 nm) nanodiamonds purely from adamantane at pressure of 12 GPa is reported. Their structural features have been studied by Raman spectroscopy. The unusual vibration band containing a number of pronounced maxima at about 1147, 1245, 1344, and 1456 cm-1 was detected in Raman spectra. The band is confidently identified with the bending vibrational modes of CHx groups terminating the nanodiamonds surface. Excessively intense mode at 1344 cm-1 is explained by its coupling with the 1328 cm-1 diamond phonons. The Raman band found is proposed to be used for express recognition of ultrasmall nanodiamonds produced from adamantane and other hydrocarbons with a high hydrogen content. Moreover, polarized CH bonds on a diamond surface are sensitive to environmental conditions. This opens up opportunities for using the diamond produced from adamantane as ultrasmall nanosensors in biology, chemistry, and medicine