The Interaction of CF3CH2OH and (CF3CF2)2O with Amorphous Carbon Films

Abstract

Fluorinated alcohols and fluorinated ethers adsorbed on carbon films have been studied in order to model the surface chemistry of Fomblin Zdol lubricants on the carbon-coated surfaces of magnetic data storage media. The model compounds used were 2,2,2-trifluoroethanol (CF3CH2OH), which is representative of the end groups of Fomblin Zdol, and perfluorodiethylether (CF3CF2)2O, which represents the main chain of Fomblin Zdol. Temperature-programmed desorption (TPD) spectroscopy was used to measure the desorption energies of these compounds on a variety of different carbon films. Desorption energies were measured on amorphous hydrogenated carbon (a-CHx), amorphous nitrogenated carbon (a-CNx), cathodic arc carbon (CAC), and ion-beam sputtered carbon (IBC). On all carbon film surfaces the desorption energy of CF3CH2OH is higher than that of (CF3CF2)2O. The desorption energy of CF3CH2OH is higher on the a-CNx films than on the other carbon films; however, the desorption energy of (CF3CF2)2O does not depend on the type of carbon. Finally, the desorption energies are dependent upon CF3CH2OH and (CF3CF2)2O coverage, indicating that the carbon films are heterogeneous and expose binding sites with a range of affinities for adsorption. Systematic measurements of the desorption energies over a range of coverages have been used to map out the heterogeneity of all the carbon films.