Adsorption behavior of 6-Mercaptonicotinic acid on self-assembled gold nano-substrates explored by SERS combined with theoretical calculations

摘要

As a typical Raman reporter molecule, 6-Mercaptonicotinic acid (C6H5NO2S, MNA) has three atoms (i.e., N, O, and S), which could be potential to chemically interact with gold nano-surface. In the present report, the adsorption behavior of MNA on self-assembled gold nano-substrates is explored by means of surfaceenhanced Raman scattering and theoretical calculations. The results reveal that all the enhanced bands are assigned to in-plane vibrations. The ring triangle breathing coupling with CAS stretching band at 1108 cm~(-1) is enhanced a lot and redshifts to 1088 cm~(-1) in the SERS spectra. Furthermore, most of the bands related to N atom are apparently enhanced and shift in the SERS spectra. Based on the surface selection rule, it infers that MNA is vertically chemisorbed on self-assembled gold substrates through the S and the N atoms. The spectroscopic results are further interpreted by the density functional theory (DFT) calculations.