Kang Somi, Lehman Sean E, Schulmerich Matthew V, Le An-Phong, Lee Tae-Woo, Gray Stephen K, Bhargava Rohit, Nuzzo Ralph G
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Beilstein J Nanotechnol. 2017 Nov 24;8:2492-2503. doi: 10.3762/bjnano.8.249. eCollection 2017.
Herein we describe the fabrication and characterization of Ag and Au bimetallic plasmonic crystals as a system that exhibits improved capabilities for quantitative, bulk refractive index (RI) sensing and surface-enhanced Raman spectroscopy (SERS) as compared to monometallic plasmonic crystals of similar form. The sensing optics, which are bimetallic plasmonic crystals consisting of sequential nanoscale layers of Ag coated by Au, are chemically stable and useful for quantitative, multispectral, refractive index and spectroscopic chemical sensing. Compared to previously reported homometallic devices, the results presented herein illustrate improvements in performance that stem from the distinctive plasmonic features and strong localized electric fields produced by the Ag and Au layers, which are optimized in terms of metal thickness and geometric features. Finite-difference time-domain (FDTD) simulations theoretically verify the nature of the multimode plasmonic resonances generated by the devices and allow for a better understanding of the enhancements in multispectral refractive index and SERS-based sensing. Taken together, these results demonstrate a robust and potentially useful new platform for chemical/spectroscopic sensing.
在此，我们描述了银和金双金属等离子体晶体的制备与表征，该系统与类似形式的单金属等离子体晶体相比，在定量、体相折射率（RI）传感和表面增强拉曼光谱（SERS）方面具有更强的能力。传感光学器件是由依次覆盖有金的银纳米级层构成的双金属等离子体晶体，具有化学稳定性，可用于定量、多光谱、折射率和光谱化学传感。与先前报道的同金属器件相比，本文展示的结果表明，性能的提升源于银层和金层独特的等离子体特性以及产生的强局域电场，这些特性在金属厚度和几何特征方面得到了优化。时域有限差分（FDTD）模拟从理论上验证了器件产生的多模等离子体共振的性质，并有助于更好地理解多光谱折射率和基于SERS传感的增强效果。综上所述，这些结果证明了一个强大且潜在有用的化学/光谱传感新平台。
