Here we report the size reduction and effects on nitrogen-vacancy centres in nanodiamonds by air oxidation using a combined atomic force and confocal microscope. The average height reduction of individual crystals as measured by atomic force microscopy was 10.6 nm/h at 600 {\deg}C air oxidation at atmospheric pressure. The oxidation process modified the surface including removal of non-diamond carbon and organic material which also led to a decrease in background fluorescence. During the course of the nanodiamond size reduction, we observed the annihilation of nitrogen-vacancy centres which provided important insight into the formation of colour centres in small crystals. In these unirradiated samples, the smallest nanodiamond still hosting a stable nitrogen-vacancy centre observed was 8 nm.
@article{arxiv.1104.5075,
title = {Size-reduction of nanodiamonds via air oxidation},
author = {T. Gaebel and C. Bradac and J. Chen and P. Hemmer and J. R. Rabeau},
journal= {arXiv preprint arXiv:1104.5075},
year = {2011}
}