Catalytic oxidation of 4-dimethylaminobenzaldehyde by gold nanoparticles. Part II: Surface-enhanced Raman spectra

Surface-enhanced Raman spectra of 4-(dimethylamino)benzaldehyde mixed with solutions of gold nanoparticles at various values of pH show that oxidation to the corresponding acid occurs. At pH 3.0 spectra of the aldehyde are observed due to the slow reaction rate and the rapid aggregation of the nanoparticles preventing sufficient time to observe the product acid. At pH 5.4 spectra of 4-(dimethylamino)benzoic acid are observed. At pH 11.1 spectra that indicate the presence of a variety of reaction products are observed. Vibrational wavenumbers and tentative assignments are presented.