Raman spectral study of metal-cytosine complexes: a density functional theoretical (DFT) approach

The fluctuation of surface-enhanced Raman scattering (SERS) spectra has been an obstacle to the analysis of the adsorbate on the metal surface. In this paper, we aim at using the density functional theory (DFT) to study the fluctuant Raman spectra of the cytosine molecule which interacts with a coinage metal atom or cation via N1 and N3 sites. The results show that the adsorption site strongly influences the Raman spectral property of cytosine molecule, especially the relative intensity of some bands. In addition, the SERS spectra of cytosine which is adsorbed on the gold, silver, and copper electrodes are measured, and the possible orientation and adsorption site of the cytosine molecule adsorbed on metal electrodes surface are proposed with the help of DFT simulations.