Effect of thin-cavity thickness on PM IRRAS background appearance of the solution/gold interface
LE3 .A278 2012
Bachelor of Science
Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM IRRAS) is a surface analytical technique that allows for the investigation of ultra-thin films of molecules adsorbed at a metal surface. The application of this technique to water-soluble surfactants, such as corrosion inhibitors, has proved particularly challenging as the contribution from the bulk analyte to the PM IRRAS signal has to be removed before signal can be attributed to surface species. This thesis continues development of PM IRRAS as a method for the investigation of corrosion inhibitors, benzotriazole (BTAH) and benzimidazole (BIA), at charged metal surfaces. PM IRRAS spectra have been simulated using the optical constants of these molecules in deuterated water (D2O). The simulations predict that PM IRRAS investigations of BTAH and BIA at the electrolyte/gold surface shall be successful, in the region of the prominent 1450 cm-1 absorption band. In the process of PM IRRAS simulations, it was discovered that the thin-cavity thickness of the PM IRRAS flow cell alters the appearance of the spectra background, which may result in difficulty when baseline is subtracted during data processing, thus affecting the resulting spectra. A thin-cavity thickness of 3.0 μm was determined to provide the smoothest background, thus facilitating peak elucidation, while ensuring the bulk analyte does not contribute significantly to the PM IRRAS signal.
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