UV plasmonic materials such as aluminum and magnesium have drawn attention in recent years due to their potential applications in plasmonic enhanced label free sensing and UV light sources and detectors. In this paper, nanoapertures in Al and Mg thin film have been used to study the lifetime modification and net fluorescence intensity of the freely diffusing UV dye p-terphenyl. Previously, Jiao et al reported lifetime reduction of 3.5 times for Al nanoapertures with diameter 60nm. In this paper, lifetime reduction of 5.4 times is observed for Al nanoapertures with smaller diameter 40nm. For the firs time, lifetime modification in Mg nanoapertures is reported. For the same aperture geometry, Mg nanoaperture show higher Purcell factor and excitation enhancement due to lower loss of Mg in UV range . We observe 7.3 times lifetime reduction for Mg nanoapertures with 40nm diameter.
We also studied numerically bowtie antenna for native fluorescent enhancement and have observed ~180x net enhancement, ~35x radiative rate enhancement. Those results suggest that label free sensing of amino acids and proteins are promising.
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