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The anodic electrochemical behavior of copper in bromide medium, in the absence and presence of hexamethylenetetramine (HMTA), has been studied, using electrochemical and spectroelectrochemical techniques. The copper dissolution in the absence of HMTA was dependent on mass transport of bromide ions. A porous CuBr ®lm was formed at positive overpotentials. The ®lm growth mechanism followed the nucleation, growth and superposition (NGS) model, with instantaneous nucleation and a diusion controlled growth of a three dimensional ®lm. In the presence of the inhibitor, a passivant Cu/HMTA/Br À ®lm was observed. This ®lm has slow growth kinetics, favored by mass transport. The inhibitory eect was observed for the potential range between 0 mV and +800 mV (SCE). A maximum inhibitory eciency, near 100%, was observed for 15 mM HMTA. The nature of the passivant ®lm was con®rmed by in situ surface-enhanced Raman scattering (SERS) and SEM/EDX measurements. #

Two kinds of films, named A and B, ofpolydiphenylamine (PDPA) electrochemically synthesized have been characterized by ex situ resonance Raman, FT-IR and UV-Vis-NIR Reflectance spectroscopies. The ex situ RR spectra of the films showed differences, that were rationalized assuming the predominance of the diphenosemiquinone aminoimine structure in the film A, while in the film B the diphenoquinone diimine segments were predominant. The variation of the nature of the film adsorbed on the electrode with the applied potential has been monitored by means of the in situ resonance Raman technique. The bands characteristics of the diphenosemiquinone aminoimine moiety are dependent on the laser power employed, being converted to diphenoquinone diimine and diphenyl diamine segments. This result was confirmed by FT-IR spectra of the film A after heating. The thermal behavior of the films was monitored by thermogravimetry (TG), derivative thermogravimetry (DTG), and differential scanning calorimetry (DSC).

The spectroelectrochemical behavior of the binuclear complex [Fe2(CN)l&]6-, where L is the bridging ligands 4,4'-bipyri&ne (bipy) or pyrazine (pz), has been investigated by surface-enhanced Raman spectroscopy, in the visible and in the near-infrared, on silver and gold electrodes. The vibrational frequencies of bipy were the same whether I1 or I11 was the oxidation state of the metal ions. However, shifts to higher energies of the VCN bands for both complexes have been observed as the oxidation states of the metal ions changed from I1 to 111. The SERS frequencies were also higher than the values observed in the normal Raman spectra of the complexes in solution. For potentials more negative than -1.2 V, the ligands were reduced and the SER and m -S E R spectra presented marked changes with the appearance of new bands. In the case where bipy was the bridge ligand, the results have shown that vibrational modes involving the bridge ligand and the CN or Fe-CN bonds were enhanced while for pz only the latter vibrational modes were observed. This unlike behavior was assigned to differences in the structure of the ligand in relation to metal surface. The dependence of vCN frequency on the applied potential has shown that this mode is enhanced by a charge transfer mechanism, ligand (CN) to metal, while the dependence of the SERS intensity on the applied potential and laser excitation energy has shown that a charge transfer mechanism, metal to a n* orbital of bipy ligand, is responsible for the enhancement of the bipy vibrational modes. Through the use of the data obtained from the plot of Vmax (potential of maximum SERS intensity) vs laser energy, an energy diagram for the adsorbed [Fe2(CN)l~bipy]6-complex is proposed.

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