SERS detection of polycyclic aromatic hydrocarbons on a bowl-shaped silver cavity substrate

Trace detection of polycyclic aromatic hydrocarbons (PAHs) by surface-enhanced Raman scattering (SERS) on a metal sandwich substrate bridged by 1,10-decanedithiolis is reported in this work. The bowl-shaped silver cavity (BSSC) thin film bottom layer was prepared by electrodeposition using a closely packed monolayer of 500 nm diameter polystyrene spheres as a template. The as-prepared silver cavity array has proven to be a SERS-active substrate with excellent performance and reproducibility when using p-aminothiophenol (PATP) as the probe molecule. A 1,10-decanethiol monolayer was then assembled on the silver film to concentrate PAHs within the hot-spot of SERS detection. The top layer of silver was introduced by an S-Ag bond between the thiols of the 1,10-decanethiol and the silver nanoparticles. The proposed structure was employed to perform the SERS-based PAH detection. The measured SERS spectra enabled the easy detection of anthracene and pyrene; the two PAH compounds can be detected over a wide concentration range and the detection limit of anthracene and pyrene was 8 and 40 nM, respectively. The results demonstrate that the new SERS substrate is suitable for the quantitative identification of non-polar organic pollutants like PAHs.