Diamond–Water Coupling Effects in Raman and Photoluminescence Spectra of Nanodiamond Colloidal Suspensions

The interaction of nanodiamond (ND) particles produced by detonation synthesis with water molecules in ND water suspensions was studied using Raman and photoluminescence spectroscopy. To address the role of the surface chemistry of ND particles, NDs with heterogeneous surface groups as well as ND particles enriched with carboxyl-, hydroxyl-, and fluorine-containing surface groups were investigated. The influence of the nanodiamond particles on the shape and position of the water valence band in the Raman spectra of ND water suspensions was demonstrated for the first time. Changes in the water band parameters take place up to 1.5 mg/mL of NDs in all studied suspensions and are most pronounced for the ND functionalized with COOH groups. A correlation between increasing ND luminescence intensity and strengthening of hydrogen bonds formed at the interface of ND and water molecules in water suspensions of variously functionalized NDs was found. The most intense ND luminescence was detected for the ND functionalized with OH groups, forming the strongest hydrogen bonds among the studied samples.