Interaction of Alcohols with a-CHx Films

Temperature programed desorption has been used to study the desorption kinetics and desorption energies of a set of alcohols and fluorinated alcohols adsorbed on an a-CHx film. The alcohols serve as models for the hydroxyl end groups of Fomblin Zdol, the lubricant most commonly used with the amorphous carbon overcoats sputtered onto the surfaces of magnetic data storage disks. Temperature programed desorption has been used to measure the desorption energies of the alcohols over a range of coverages and to compare the desorption energies of fluorinated and hydrocarbon alcohols. The desorption energies are all coverage dependent and decrease with increasing alcohol coverage. This is believed to be due to heterogeneity of the a-CHx films surface. In all cases the low coverage desorption energies of the fluorinated alcohols were found to be higher than those of their hydrocarbon counterparts. The implications of this observation are that the interaction of the alcohols is through hydrogen bonding of the hydroxyl groups to the a-CHx films. This conclusion is consistent with that reached in a similar study of the adsorption of alcohols to the surfaces of a-CHx films.