Thermal and electron-stimulated chemistry of Fomblin–Zdol lubricant on a magnetic disk

The thermal and electron-induced decomposition of Fomblin–Zdol lubricant on a rigid magnetic disk with a hard carbon overcoat are studied by temperature-programmed reaction/desorption spectroscopy and electron stimulated desorption. The thermal spectroscopy shows two desorption features peaked at 640 and 700 K resulting from decomposition of the Fomblin–Zdol molecules. The threshold temperature for dissociation of the Fomblin–Zdol molecule is at 500–550 K in accordance with the known thermal stability of the free molecule. HF originating from thermal reactions with either surface OH or surface CH groups is a prominent desorption product. Electron impact also causes Fomblin–Zdol dissociation. Two efficient mechanisms for electron impact dissociation have been resolved separately above and below the ionization threshold of ∼14 eV. The low-energy process is likely due to the formation of negative ions followed by dissociation (dissociative electron attachment) and has a cross section of ∼2×10−16 cm2. These results show that Fomblin–Zdol as a lubricant on a magnetic disk is inherently unstable thermally and in the presence of triboelectrons.