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Abstract
This thesis encompasses in situ vibrational spectroscopic and electrochemical studies of several electrodeposition additives on copper surfaces. The potential dependent behaviors of benzotriazole (BTAH) and 1-(methoxymethyl)-1H-benzotriazole (MeOMe-BTA) on copper surfaces were addressed. Polarization modulation infrared reflection-absorption spectroscopic (PM-IRRAS) results showed that the identity of the anion in the supporting electrolyte has a significant effect on the formation and decomposition of the Cu(I)BTA multilayer surface complex. In chloride-containing solution, the Cu(I)BTA film is more easily formed. This film can be completely reduced upon excursion to more negative potentials. In sulfuric acid solution, the Cu(I)BTA film is formed less readily at more positive potentials and cannot be completely reduced at more negative potentials. The differences in the film formation/decomposition in the two electrolytes are attributed to coordination of the anion (Cl− or HSO 4−) to the Cu(I) center of the Cu(I)BTA complex. MeOMe-BTA does not form a complex with copper due to blockage of one of the triazole ring nitrogens.
The potential dependent behaviors of sodium bis-(3-sulfopropyl)-disulfide (SPS) and 3-mercapto-1-propanesulfonate (MPS) on copper surfaces were studied with surface-enhanced Raman spectroscopy (SERS). The results suggest that SPS interacts with the Cu surface primarily through the sulfur(s) of the S-S portion of the molecule and that MPS interacts with the Cu surface through the thiolate sulfur. The two molecules associate with the surface in a similar manner. SPS and MPS do, however, exhibit different voltammetric responses; the differences may be due to the S-S linkage in SPS. At potentials negative of ca. −0.40 V, SPS desorbs from the Cu surface and/or reacts with Cu, possibly to form a Cu(I) complex. Mass spectrometric data suggests that SPS forms a complex with copper.
The potential-dependent behavior of silicotungstate, α-SiW 12O404−, on copper, silver, and gold electrode surfaces was investigated using SERS and PM-IRRAS. The results show that silicotungstate interacts with Cu surfaces. This interaction is shown to be potential-dependent; α-SiW12O404− associates with the Cu surface to a greater extent as the potential is stepped negatively. As the potential is stepped back positively, the α-SiW 12O404− still interacts with the surface.
