Large available volume particles for enhanced deep UV local Raman sensing

Shuang Fang Lim; Janina Wirth; Angel Fernandez Bravo; Peter James Schuck; Hans D. Hallen

doi:10.1117/12.2529434

9 September 2019 Large available volume particles for enhanced deep UV local Raman sensing

Shuang Fang Lim, Janina Wirth, Angel Fernandez Bravo, Peter James Schuck, Hans D. Hallen

Proceedings Volume 11086, UV and Higher Energy Photonics: From Materials to Applications 2019; 110860Z (2019) https://doi.org/10.1117/12.2529434
Event: SPIE Nanoscience + Engineering, 2019, San Diego, California, United States

Abstract

The combination of resonance Raman with deep UV excitation, DUVRR, gives greater selectivity and eliminates background fluorescence, enabling sensitive detection of UV absorbing nucleotide bases and amino acids. We demonstrate this combination with our 3D nanopore structure design. Resonance Raman is specific to a molecule absorbing at the excitation, while plasmon resonance of a small, shape-, index- and size- tuned metal dramatically increases the electric field strength in the active region. The 3D nanostructure exploits nanopores that retain the advantages of small-gap antennas but increases the ease of fabrication, availability, and detection volume compared to conventional plasmon-based designs, such as gaps between two particles, by being inherently single particle, with edge enhancement open to diffusion, and by possessing a large number of pores per particle. We show the large local field enhancement (hot spots) of the pores. Comparisons with an Al and silica coated/uncoated microsphere template with/without nanopores clearly show a significant blue shift of the 280 nm peak to (the more useful) 265 nm, in the presence of a hollow sphere with nanopores. Raman measurement of Tryptophan on an aluminum nanopore structure with excitation from our tunable OPO system in the visible and deep UV region indicate visible excitation causes more fluorescence and is less specific for the tryptophan, even displaying a Raman peak at the silicon substrate, while the deep-UV Raman spectra, at an energy close to the nanopore resonance, shows no substrate signal and peaks with close correlation to the known tryptophan vibrations.

Conference Presentation

Citation Download Citation

Shuang Fang Lim, Janina Wirth, Angel Fernandez Bravo, Peter James Schuck, and Hans D. Hallen "Large available volume particles for enhanced deep UV local Raman sensing", Proc. SPIE 11086, UV and Higher Energy Photonics: From Materials to Applications 2019, 110860Z (9 September 2019); https://doi.org/10.1117/12.2529434

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