SURFACE-ENHANCED RAMAN-SCATTERING OF TRIPHENYLMETHANE DYES ON COLLOIDAL SILVER

Surface Raman spectral studies of triphenylmethane dyes on colloidal silver were carried out. An assessment of the surface and solution spectra led to the conclusion that the dye molecules are most likely lying parallel to the surface of the sol and adopting C3 symmetry. The major vibrational changes suggest that the most important center of interaction is the central carbonium ion, since the greatest changes are observed for the vibrations of the central bonds and only small changes are observed for the N-phenyl stretching modes. For a fixed concentration of sol the lowest level of detection was 5 x 10(-8) M.