Can we predict the location of impurities in diamond nanoparticles?

Although most commercial nanodiamonds contain impurities, it is still largely unknown whether a given species will be located within the core or at the surface of the nanocrystals. This question is significant, since in the former case a suitable atom may act as a dopant, but in the latter case it will merely be an adsorbate. Presented here are density functional tight-binding simulations examining the potential energy surface of substitutional nitrogen and boron in diamond nanocrystals, directly comparing results for a number of crystallographically inequivalent sites. The results predict that both nitrogen and boron are metastable within the core of bucky-diamond and nanodiamond, and are therefore unlikely to be stable as dopants within these nanoparticles.