Surface‐enhanced Raman spectroscopy of pyridine and thiophenol on non‐aqueous colloidal copper

Surface‐enhanced Raman (SER) spectra of pyridine and thiophenol on a copper colloid prepared in isopropanol were obtained. Aggregation of the colloid, which occurs only slowly in the presence of adsorbates, was found to be essential to the detection of SER spectral features with excitation at 660 nm. As with aqueous copper sols, thiophenol was found to adsorb more strongly than pyridine to the copper surface. However, both adsorbates required greater concentrations in the bulk solution than for aqueous systems in order for SER features to be observed.