The main peaks on normal Raman spectrum of Thiram were characterized at 371, 576, 1414 and 1456 cm-1 responsible for the stretching vibrations of C–S, C=S, S–C–S and C–N groups, respectively. Otherwise, the main peaks of Thiram-Cu20 SERS spectrum were found at 534, 874, 982, 1398 and 1526 cm-1 corresponding to the stretching vibrations of S–S, C-S, S–C–S, C–N and CH3–N bonds, respectively. The SERS chemical enhancement of Thiram by Cu20 cluster was about 2 and 6 times stronger than those obtained from Ag20 and Au20 cluster, respectively. The chemical enhancement mechanism was also explained by analyzing HOMO and LUMO energies gap and density of states. |
