| The utility of Real-Time Polarization Modulation (RTPM) to enhance the sensitivity of FTIR spectroscopic examination of surfaces was evaluated. Also, two-dimensional correlation was evaluated as a method of data treatment for spectra from complex systems. RTPM uses rapidly modulated linearly polarized light to produce interspersed sample and background spectra of a sample on a solid surface. The sample systems considered are the electrooxidation of thiocyanate ion, imidazole or glucose in basic medium at a copper electrode, and a copper surface in a humid, corrosive atmosphere.; Comparison of the RTPM spectra with the more conventional Static Linear Polarization (SLP) spectra for thiocyanate ion and imidazole experiments shows the migration of the solute from the solution to the surface layer with increasing potential, and the formation of new products on the surface, such as Cu(I)SCN, and the change from imidazole in solution to imidazolate ion bound to the surface. Furthermore, the RTPM data indicate that not all the imidazole ions are oriented perpendicularly to the surface, and that there is no change in the orientation of the ions with increasing potential.; The initial stages of glucose oxidation and the corrosion experiments were monitored with RTPM spectroscopy, and the data were subjected to two-dimensional correlation. For glucose, spectral data collected between −1.0 to 0.0 V indicate that the oxidation of glucose begins at a very low potential, and the carboxylate ion formed binds first as a monodentate ligand and shifts to a bidentate bridging ligand at higher potentials; there is some evidence for the formation of an ene-diol intermediate.; In the corrosion experiments on a copper surface in a humid atmosphere containing various mixtures of SO2, NO2 and HCl, both H+ and NO2 have been identified as potentiators in the formation of SO2 containing films.; RTPM enables the rapid acquisition of spectral data with reasonable signal-to-noise ratio from thin films. Two-dimensional correlation data treatment is useful in the assignment of spectral peaks from complex samples, as well as determining the processes occurring. |
