Surface-enhanced Raman spectroscopy substrate based on Ag-coated self-assembled polystyrene spheres

The silver (Ag) films were deposited on the monodispersed polystyrene spheres that were drop-coated on hydrophilic glass substrates in order to form a self-assembled 2D monolayer. Thus prepared Ag films over polystyrene nanospheres (AgFONs) were used to record the surface-enhanced Raman scattering (SERS) spectra of rhodamine 6G (R6G) and pyridine (lambda(ex) = 514.5 nm). AgFONs were prepared by depositing 120,180 and 240 nm thick Ag layer on the 1000 nm polystyrene spheres and 80,120, 160 and 200 nm thick Ag layer on the 350 nm spheres as well as on their mixture (350 + 1000 nm). The silver was deposited by electron beam evaporation technique. The best enhancement of the Raman signal for both test molecules was obtained using 180 nm Ag film deposited on the 1000 nm spheres and using 80 nm Ag film deposited on the 350 nm polystyrene spheres. The lowest detectable concentrations of R6G and pyridine were 10(-9) mol L-1 and 1.2 x10(-3) mol L-1, respectively. This study has shown that AgFONs could be regarded as good and reproducible SERS substrate for analytical detection of various organic molecules. (C) 2017 Elsevier B.V. All rights reserved.