[IR, Raman and DFT studies of Sudan red III and IV].

Infrared spectroscopy (IR) and normal Raman spectroscopy (NRS) of Sudan red(III) and Sudan red(IV), and surface -enhanced Raman spectroscopy(SERS) of them on Cu-Ag nanocomposite material were reported in the present paper. The density functional theory (DFT) calculation was applied to calculate IR and NRS on a B3LYP/6-311+G (d, p) level, and the theoretically calculated spectra were carefully compared with the obtained experimental spectra. The vibrational peaks were assigned by the software of Gauss view 5.