Coverage Analysis of Molecularly Thin Lubricant Films Using Molecular Dynamics Simulations and CAICISS Measurements

In order to examine the coverage of molecularly thin lubricant films on magnetic recording media, a method using coaxial impact collision ion scattering spectroscopy (CAICISS) is proposed. In this method, it is presumed that if a lubricant film of perfluoropolyether completely covers the surface, the fluorine-to-carbon atomic ratio (F/C ratio) of the surface should become 2. In this paper, we reproduce molecularly thin lubricant films on a carbon overcoat by full-atom molecular dynamics simulations, and calculate their coverage and F/C ratios. assuming the CAICISS measurement, the F/C ratios were computed considering the shadow cones formed behind the surface atoms. By comparing the F/C ratios with the coverage, we conclude that the coverage measurement method using CAICISS can accurately evaluate the coverage of molecularly thin lubricant films.