  Fano resonance is a unique feature of interacting quantum systems, exhibiting
resonance shapes distinctively different from conventional symmetric resonance
curves. Recently, Fano resonances have been found in plasmonic nanoparticles,
photonic crystals, and electromagnetic metamaterials. Here we report Fano-like
photoluminiscence curves in nanodiamond solutions as a result of incoherent
combination of two or more scattering and fluorescence processes. We argue
that, analogously to Fano resonances, the steep asymmetric dispersion of the
photoluminiscence profile in nanodiamond solutions, in combination with
biologically-compatible spectral features characterizing nanodiamond
fluorescence, can find promising biometric applications in several areas such
as bio-sensors, bio-switches and bio-filters.
