| Surface-enhanced Raman spectroscopy is one of the spectroscopic techniques used to investigate the orientation, and conformational changes of pyridine, heme proteins and surfactants adsorbed on a silver (Ag) electrode.; For pyridine, its SERS was studied in different electrolyte solutions and compared with theoretical calculations. We showed that the adsorbate has no effect on the metal-nitrogen band at approximately 230 cm−1 , that is, when the SERS was taken in different electrolyte solutions. In addition, a very negative voltage results in changed orientation of water molecules and solute toward the electrode surface.; Heme proteins such as horse skeletal muscle myoglobin and horse heart cytochrome c were also investigated for the oxidation state, spin state, and the orientation of the iron atom of the heme chromophore. It was found that at a specific voltage, the iron of the heme chromophore can exist as Fe 2+ or Fe3+; the chromophore can have an orientation in the plane or out of the plane of the tetrapyrrole ring.; The structure of surfactants and their interaction with the electrode surface were also investigated SERS. The interaction between the electrode surface and the surfactants was found to be dependent on the charge of the head group and electrode potential applied. Over a range of voltage from −0.1V to −0.9V, most of the surfactants have a head-on orientation toward the electrode surface using a saturated calomel electrode (SCE) as a reference electrode. However, at a relatively more negative voltage, the polar head group of the surfactants is directed away from the electrode surface. With the exception of cetylpyridinium chloride (CPC), all of the surfactants have the ability to form a protective layer of film that prevent hydrogen evolution at a very negative voltage, i.e., beyond −0.9V.; Finally, we have incorporated heme proteins inside DDAB surfactant, and an increase in electron transfer has been observed using cyclic voltammetry and SERS. The increase in electron transfer can be explained by the fact that the DDAB surfactant has provided a specifically favorable orientation of the protein toward the electrode surface facilitating electron transfer between the electrode and the molecules. |
