In Situ Detection of Trace Furfural in Aqueous Solution Based on Au Nanoparticle/Au Film Surface-Enhanced Raman Spectroscopy

Figure 2

The calculated near-field electric distribution in different configurations excited at 632.8 nm: ((a), (b)) Au dimer (60 nm) with interparticle spacing of 5 nm located above (a) the Au film and (b) the SiO₂ support, (c) Au dimer (60 nm) with interparticle spacing of 1 nm located above the Au film, and (d) Au dimer (20 nm) with interparticle spacing of 5 nm located above the Au film. The refractive index is 1.33 for all configurations. The insets with red arrows show the propagation direction of the incident light perpendicular to the dimer structure with polarization parallel to -axis.

(a)

(b)

(c)

(d)