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. 2024 Feb 28;124(5):2512–2552. doi: 10.1021/acs.chemrev.3c00662

Figure 4.

Figure 4

Strong coupling of water OH stretches CuSO4(H2O)1 with surface plasmon polaritons. (a) Schematic of the plasmonic substrate with 2 μm CuSO4(H2O)1 on top. The red dotted lines show the Raman map region. (b) Raman depth map with horizontal dashed lines indicating the boundaries of the different regions. The scale bar is 4 μm. (c) Spectrum obtained by the Raman map above the substrate. (d) Spectrum obtained from the film region showing the prominent peaks of CuSO4(H2O)1 at 1118 and 1048 cm–1. (e) Spectral absorbance (normalized) of a bare plasmonic substrate (red dashed), a CuSO4(H2O)1 thin film on Al2O3 with a gold back reflector (blue), and the spectrum of the CuSO4(H2O)1 thin film on top of the plasmonic substrate composed of a nanodisk (diameter = 680 nm) with a plasmonic resonant frequency of 3534 cm–1 (black). The black spectrum shows clear doublet peaks, indicating strong coupling between OH stretches and plasmonic modes. Reproduced with permission from ref (28). Copyright 2021 American Institute of Physics.