High resolution electron energy loss spectroscopy study of Fomblin Z-tetraol thin films^a)

High resolution electron energy loss spectroscopy has been used to obtain vibrational spectra of Fomblin Z-tetraol lubricant films on a commercial magnetic hard disk. The energy loss intensities of the $ν(CF2)$ stretching mode are roughly independent of scattering angle up to angles of $Δθ<14°$ indicating that they are excited by impact scattering. As a consequence there is little information that can be gleaned from the spectra about molecular orientation on the surface. A negative ion resonance enhances the energy loss cross section of the $ν(CF2)$ stretching mode at the impact energy of $EI=4eV$⁠. It is possible that this resonance is associated with the known sensitivity of fluorocarbons to electron induced dissociation. Annealing the disk sample to $T=700K$ causes a dramatic decrease in the intensity of C–F stretching modes and an increase of the loss features due to C–H stretching. This indicates that the Fomblin Z-tetraol has decomposed and is exposing the $a‐CHx$ overcoat on the magnetic media surface.