Size effects on surface chemistry and Raman spectra of sub-5 nm oxidized high-pressure high-temperature and detonation nanodiamonds

In the study, we prepared and compared sub-5 nm nanodiamonds (ND) prepared by detonation and high-pressure high-temperature (HPHT) synthesis. The work contributed to a better understanding of the Raman spectra of nanodiamonds and their size dependence down to 3 nm and opened up new possibilities in determining their size using low-frequency "breathing" modes, which were detected in nanodiamonds for the first time.