Infrared spectroscopic analysis of sub-monolayer perfluoropolyether Z-Tetraol films used in boundary lubrication.

Infrared specular reflection spectra of Z-Tetraol on a gold substrate was simulated and studied experimentally. The simulated spectra were obtained using a classical dispersion analysis coupled with solutions of Maxwell's equations for transmission and reflection of electromagnetic radiation. The simulated spectra, which are based on a randomly oriented sample, provide excellent fits for Z-Tetraol over a wide film thickness range. Spectroscopic data are provided for the Z-Tetraol -(CF2O)p-(CF2CF2O)q- main chain. The differences in the transverse and longitudinal optical infrared spectra are discussed for off-normal reflection spectra in the thin film limit. Corrections to the infrared reflection spectra for sub-monolayer coverage using effective medium theory are also discussed.