SERS spectra (a,c) and enhancement factor (EF) of monolayer R6G adsorbed on hemispherical nanostructures (b,d). Nanostructures with different thicknesses of adhesion layer. (a,b) Cr (Chromium). (c,d) Ti (Titanium) between the quartz substrate and noble metal film. The unpatterned samples were coated with 5-nm-thick adhesive layer.
Zhu et al. Nanoscale Research Letters 2014 9:25 doi:10.1186/1556-276X-9-25