Photoelectron Spectroscopy Investigation of Oligoaniline-Iron Oxide Interfaces for Understanding Corrosion Inhibition

Abstract

<p> Poly aniline (PANI) is capable of inhibiting corrosion on iron by inducing the formation of a passive oxide film. The mechanism by which PANI does this is unknown to the scientific community. We have used photoemission spectroscopy of thin films of a model PANI oligomer to investigate the PCAT -iron interaction. </p> <p> The oligomer chosen was a phenyl-capped aniline tetramer (PC AT). Thin films of PCAT were prepared by in-vacuum physical vapor deposition to obtain extremely thin films of thickness ranging from -5A to over 1 Onm. </p> <p> Films were investigated with a photoemission electron microscope (PEEM) using synchrotron radiation to obtain spatially resolved valence band photoemission spectra. Analysis of PEEM results suggest that PCAT is capable of migrating several microns along the substrate surface, and causes a decrease in substrate work function wherever present. </p> <p> High-resolution core level and valence band photoemission spectroscopy using a laboratory-based photon source was used to characterize the substrate and PCAT properties near the PCAT-substrate interface. Characterization of an in-situ thin film deposition reveals that the iron substrate exhibits band bending in it oxide as well as a decrease in work function by 0.7eV upon adsorption of PCAT. </p>