Fig. 1From: Quantitative Analysis of Single and Mix Food Antiseptics Basing on SERS Spectra with PLSR Method a SEM morphology of the HfO2 ultrathin film-coated Ag NR SERS substrate; b TEM morphology of a HfO2 ultrathin film-coated Ag NR; c high-resolution TEM of HfO2 ultrathin film outside the Ag NR; d Raman spectra of 1 × 10−6, 1 × 10−7, 1 × 10−8, and 1 × 10−9 M 4-Mba adsorbed on SERS substrate; e absorption spectrum of the HfO2 ultrathin film-coated Ag NR SERS substrate; f the dotted lines are Raman spectra of 1 × 10−6 M 4-Mba measured on 10 different sites randomly selected on SERS substrate, and the solid line is the average spectrum of themBack to article page