Desorption kinetics and energetics of monodisperse Fomblin Zdol from carbon surfaces

Desorption is one of the mechanisms of lubricant loss from the surfaces of data storage media. This work has studied the desorption of monodisperse sa mples of a typical perfluoropolyalkyl ether lubricant, Fomblin Zdol, from t he surface of graphite. Desorption is observed to occur molecularly through a first-order process with an energy barrier to desorption, AE, that is in dependent of coverage but is dependent on molecular weight. The DeltaE(des) (double dagger) of 994 and 1329 g/mole fractions were found to be 128 +/- 2 kJ/mol and 155 +/- 2 kJ/mol, respectively. The pre-exponents, upsilon, of the first-order desorption rate constant were found to have values of 10(19 .6 +/-0.3) s(-1) and 10(21.1 +/-0.3) s(-1) for the 994 and 1329 g/mole Zdol fractions, respectively. These results clearly reveal the chain length dep endence of the DeltaE(des)(double dagger), and the high values of the pre-e xponents are similar to those observed for desorption of other oligomeric s pecies from graphite.