Tuning the Optical Gap of Nanometer-Size Diamond Cages by Sulfurization: A Time-Dependent Density Functional Study

The optical gap of nanometer sized diamond cages, i.e., diamondoids, lies in the ultraviolet spectral region. Here we show by hybrid functional based time-dependent density-functional calculations that, by varying the number of C=S double bonds at the surface of diamondoids, the absorption onset can be tuned toward the infrared spectral region. Our finding has an important implication for in vivo biological applications where toxic and unstable dye molecules may be substituted by the luminescent sulfurized diamondoids.