Scaling the response of nanocrescent antennas into the ultraviolet

We investigate the scaling of nanocrescent antennas for applications at UV wavelengths. These antennas have been extensively studied at infrared wavelengths due to their relative ease of fabrication [1] and tunability [2] via nanosphere template lithography. Their response at UV wavelengths, however, has not been characterized. There are numerous motivating factors for investigation of UV plasmonics. One example is improving the intrinsic fluorescence of biomolecules. Biomolecules such as peptides and proteins contain amino acids, three of which are intrinsic fluorophores: phenylalanine, tyrosine and tryptophan. These aromatics absorb at wavelengths between 220- nm and 280-nm and emit at wavelengths between 320-nm and 370-nm. Their fluorescence quantum efficiency is however very low. Nanoantennas could prove useful in more efficiently coupling energy between the far field and the molecule, thus improving absorption cross-section and quantum yield. Increasing intrinsic fluorescence is advantageous in label-free detection to study molecular binding without affecting their kinetic rates.