Effect of Au Polymer Adsorption Sites on Surface Enhanced Raman Spectroscopy of Amitrole Molecule

Amitrole is a chemical herbicide in the form of white crystalline powder. It is extremely destructive to the environment, and heavy use can contaminate food and cause cancer. There are relatively few researches on Raman enhancement mechanism of amitrole molecules using density functional theory. Therefore, a model describing the adsorption pattern between the molecule and the substrate was established to predict the surface-enhanced Raman spectrum of amitrole molecules. First, Multiwfn and VMD software were used to calculate the surface electrostatic potential distribution of amitrole molecules and search for the best coordination position between amitrole molecules and Au atoms. It can be obtained that N-1, N-4 and N-6 is the best place for amitrole molecules to coordinate with Au. Based on density functional theory, software GaussView5.0 and Gaussian09, was used to optimize the geometric configuration of amitrole molecules by B3LYP/6-31++ G(d, p) basis set. And 6-31++ G(d, p) (C, H, N)/Lanladz(Au) basis set was used to calculate the conventional Raman scattering spectra of amitrole molecules and the surface adsorption of amitrole molecules and Au-4 clusters and Au-6 clusters enhanced Raman scattering spectra. Finally, feature peak identification and comparison are carried out. The results show that the position of the characteristic peaks does not change greatly, but the intensity of some characteristic peaks increases obviously. In the complex formed by coordination between Au and the Raman activity of amitrole molecules was obvious at 1 064, 1 200, 1 392 and 1 592 cm(-1). In the complex formed by coordination between Au and N-4 the Raman activity of amitrole molecules was obvious at 1 304 cm(-1). In the complex formed by coordination between Au and N-6, the Raman activity of amitrole molecules was obvious at 1 064, 1 520 and 1 592 cm(-1).Through comparison, the compound formed by coordination between Au and N-1, N-6 has a better enhancement effect, and the maximum enhancement of characteristic peak reached 41, 81, 55 and 96 times respectively. The results show that the complexes formed by coordinating Au with N-1 and N-6 have a better reinforcement effect. The maximum enhancement factor of Au-4, polymer and Au-6 polymer with N-1 adsorption reached 41 and 81 times respectively; The maximum enhancement factor of Au-4, polymer and Au-6 polymer with N-6 adsorption reached 55 and 96 times respectively. Amitrole molecules and Au atoms have an obvious Raman enhancement effect. When the number of Au polymers increases from four to six, the Raman spectrum enhancement effect is obvious. This work laid a foundation for studying the SERS enhanced mechanism of amitrole molecules.