Optical properties of nanodiamond suspensions

The optical properties of nanodiamond suspensions have been calculated. The main supposition is that carbon dimers, which in many aspects are analogous to Pandey chains $(2\times 1)$ on the surface of bulk diamond, are formed on the surface of nanodiamonds due to the surface reconstruction. All experimentally observed features of the absorption of nanodiamond suspensions have been explained on the basis of these ideas. Whereas the diamond nucleus does not absorb light in the visible spectral range, dimers on the surface of the diamond core absorb light in the entire range of optical wavelengths. In addition, there are two features at energies close to $1.5$ and $5$ eV in their absorption spectrum.