COMPARISON OF SURFACE-ENHANCED RAMAN AND HYPER-RAMAN SPECTRA OF THE TRIPHENYLMETHANE DYES CRYSTAL VIOLET AND MALACHITE GREEN

Vibrational spectra of two dyes, malachite green and crystal violet are presented. Raman and hyper-Raman spectra are recorded as surface-enhanced (hyper-) Raman spectra on silver colloids. These data are compared to the respective IR spectra with respect to the point group of the molecules (C-2 and C-3) Theoretical calculations (PM3 semiempirical) and polarized Raman spectra are used to give an assignment of some vibrational bands. The advantage of SERS (surface-enhanced Raman scattering) and SEHRS (surface-enhanced hyper-Raman scattering) is discussed for the analysis of vibrational spectra.