Surface modification of nanodiamond: Photoluminescence and Raman Studies

Abstract We report modifications in structural and surface properties of carboxylated nanodiamond (cND) due to thermal annealing from 150 °C to 900 °C and gas treatments (hydrogen/argon) at 650 °C. Modifications are manifested using FTIR, photoluminescence and Raman spectroscopic techniques. Significant enhancement of photoluminescence intensity and transformation of the shape of luminescence band is observed for gas treated cNDs and for thermally annealed cNDs at 850 °C. Similar enhancement is observed at various excitations as well as for different sized hydrogen treated cNDs. Surface transformation (graphitization) is affected by various treatments which presumably change the photoluminescence properties. Simultaneously, FTIR results show enormous change in absorption frequency of carboxyl group (C=O). SEM results for gas treated samples show pyramidal structures of size ~ 26 nm. These results indicate modifying NDs surface improves the luminescence of ND, justifying their role in bio-labeling.