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Particle–Film Plasmons on Periodic Silver Film over Nanosphere (AgFON): A Hybrid Plasmonic Nanoarchitecture for Surface-Enhanced Raman Spectroscopy

Lee, Jiwon, Zhang, Qianpeng, Park, Seungyoung, Choe, Ayoung, Fan, Zhiyong, Ko, Hyunhyub
ACS Applied Materials & Interfaces 2016 v.8 no.1 pp. 634-642
Raman spectroscopy, antioxidants, electric field, glutathione, nanogold, nanospheres, periodicity, silver
Plasmonic systems based on particle–film plasmonic couplings have recently attracted great attention because of the significantly enhanced electric field at the particle–film gaps. Here, we introduce a hybrid plasmonic architecture utilizing combined plasmonic effects of particle–film gap plasmons and silver film over nanosphere (AgFON) substrates. When gold nanoparticles (AuNPs) are assembled on AgFON substrates with controllable particle–film gap distances, the AuNP-AgFON system supports multiple plasmonic couplings from interparticle, particle–film, and crevice gaps, resulting in a huge surface-enhanced Raman spectroscopy (SERS) effect. We show that the periodicity of AgFON substrates and the particle–film gaps greatly affects the surface plasmon resonances, and thus, the SERS effects due to the interplay between multiple plasmonic couplings. The optimally designed AuNP-AgFON substrate shows a SERS enhancement of 233 times compared to the bare AgFON substrate. The ultrasensitive SERS sensing capability is also demonstrated by detecting glutathione, a neurochemical molecule that is an important antioxidant, down to the 10 pM level.