Optical properties and structure of nanodiamonds

We present a theoretical study of the structure and optical properties of nanodiamonds. Using ab initio molecular dynamics simulation, we confirm that quantum confinement effects become negligible between 2 and 3 nm in size. In this size domain, specific surface reconstructions occur upon sample dehydrogenation, leading to fullerene-capped structures, or ‘bucky diamonds’ with absorption spectra similar to the experiment. We finally show that the HOMO and LUMO states are interface states in the reconstructed structures.