Raman activities computed by Gaussian were transformed into respective Raman intensities and presented as described elsewhere . Full-width at half-maximum (FWHM) of the Gaussian-type signals in the calculated spectra were 10, 15, and 25 cm -1 for normal Raman, IR and SERS spectra, respectively. Potential energy distribution (PED) analysis was performed using VEDA4 software . Visualizations of the molecular geometry and vibrations were created using GaussView and PyMOL (with PyVibMS plugin 96 ) software.