Abstract
The blue triangle nanosilver (BAgNP) sol was prepared by the two reducers of NaBH4 and H2O2. Using BAgNP as the precursor, a small spherical nanosilver (AgNP) sol in yellow was synthesized by addition of suitable amounts of X (-) (X = Cl, Br, and I). The oxidization process of BAgNP to AgNP was studied in detail by resonance Rayleigh scattering (RRS), surface-enhanced Raman scattering (SERS), laser scattering, surface plasmon resonance (SPR) absorption, and microscope techniques. It has been observed that NaCl accelerated the oxidizing BAgNP to form AgNP, and an oxidizing mechanism and quasi-nanograting Raman-scattering enhanced mechanism were developed to explain the phenomena. Using the BAgNP sol as substrate and based on the catalysis of Ti(IV) on the BrO3 (-) oxidizing safranine T (ST) molecular probe with a strong SERS peak at 1,535 cm(-1), a new catalytic SERS quantitative method was developed for the determination of 1.0 to 100 ng/mL Ti, with a detection limit of 0.4 ng/mL.