Intrinsic photoluminescence of adamantane in the ultraviolet spectral region

We report intrinsic photoluminescence in the ultraviolet for adamantane $({\text{C}}_{10}{\text{H}}_{16})$, the smallest in a series of hydrogen-passivated diamond clusters (diamondoids). The luminescence is ascribed to recombination of self-trapped excitons. The inclusion of high amounts of nitrogen into the nanodiamond's crystal lattice, using the example of urotropine (hexamethylenetetramine), is found to quench the luminescence. The results show that diamondoids are promising semiconductor nanocrystals for nanophotonic applications in the ultraviolet spectral region.