Adsorption of perfluorinated n‐alkanoic acids on native aluminum oxide surfaces

We have examined the reaction of solution and vacuum vapor deposited long chain perfluorinated n‐alkanoic acids CF3(CF2)nCOOH (n=8–16) with the native aluminum‐oxide surface using x‐ray photoelectron spectroscopy and infrared reflection absorption spectroscopy. Adsorption from solution results in slightly higher acid surface coverage than that achieved from vacuum deposition. We also find that adsorption of acids from either deposition method results in a canted, monodentate configuration. Thermal degradation is observed from the elevated temperatures employed in the vacuum deposition approach. We also find evidence of degradation of the acids from exposure to a nonmonochromatic x‐ray source.