Effect of surface morphology on surface-enhanced Raman scattering of 4-aminobenzenethiol adsorbed on gold substrates

The substrate-dependent surface-enhanced Raman scattering (SERS) of 4-aminobenzenethiol (4-ABT) adsorbed on Au surfaces has been investigated. 4-ABT is one of the very unique adsorbate molecules whose SERS spectral patterns are known to be noticeably dependent on the relative contribution of chemical enhancement mechanism vs electromagnetic enhancement mechanism. The SERS spectral patterns of 4-ABT adsorbed on gold substrates with various surface morphology have thus been analyzed in terms of the symmetry types of the vibrational modes. Almost invisibly weak b(2) type vibrational bands were observed in the SERS spectra of the 4-ABT adsorbed on An colloidal sol nanoparticles or commercially available Au micro-powders because of the weak contribution of the chemical enhancement. However, greatly enhanced b2 vibrational bands were observed in the spectra of the 4-ABT molecules adsorbed on the synthesized Au(Zn) sponge or the electrochemically roughened Au(ORC) foil caused by the strong contribution of the chemical enhancement mechanism. Copyright (c) 2008 John Wiley & Sons, Ltd.