Quantitative Analysis of Surface Functional Groups on the Amorphous Carbon in Magnetic Media with XPS Preceded by Chemical Derivatization

Abstract

Abstract In thin film magnetic recording media, the carbon protective layer and the outermost lubricant layer have a significant influence on the tribological properties. It is thought that the functional groups on the surface of the carbon influence the adsorption of the lubricant. The present study describes the identification and quantification of the functional groups on the surface of magnetic thin film media based on an X-ray photoelectron spectroscopy (XPS) preceded by chemical derivatization. The number of functional groups on the surface of the carbon protective layer was obtained from the ratio of the fluorine and carbon in the XPS spectrum. Gas-phase chemical modification was found to be preferable as a pretreatment for surface analysis, and the number of carbonyl, hydroxy, and carboxylic acid groups were directly determined. The number of hydroxy group was higher immediately after deposition, and the carbonyl group, of which the concentration rapidly increased with exposure time to air, became the most abundant. Both groups improved the affinity of the lubricant and will probably lead to a better lubricity.