Highly sensitive and stable SERS probes of alternately deposited Ag and Au layers on 3D SiO2 nanogrids for detection of trace mercury ions*

Project supported by the National Key Research and Development Program of China (Grant No. 2017YFA0207104), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA09040101), the National Natural Science Foundation of China (Grant No. Y6061111JJ), the Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No. 2015030), and the Key Technology Talent Program of Chinese Academy of Sciences (Grant Nos. Y8482911ZX and Y7602921ZX).
Tian Yi1, 2, Wang Han-Fu1, Yan Lan-Qin1, Zhang Xian-Feng1, Falak Attia1, 2, Chen Pei-Pei1, 2, †, Dong Feng-Liang1, ‡, Sun Lian-Feng1, 2, §, Chu Wei-Guo1, 2, ¶
       

(color online) (a), (b) Refractive indexes and extinction coefficients of different Ag–Au composite layers derived from the measurements by spectroscopic ellipsometry, respectively. (c) Changes of experimental Raman intensities of the peak positioned at 1610 cm−1 of the Bpy-decorated 36 nm Ag–Au/198 nm SiO2 nanogrids_h188 with different thickness ratios of Ag and Au (atomic percentage of Ag) for 514 nm wavelength laser. (d) The calculated absorption spectra of 36 nm Ag–Au/198 nm SiO2 nanogrids_h188 with different thickness ratios of Ag and Au.