Hard disk lubricant conformation and distribution via angle-resolved ESCA

Lubricant distribution on test disks for hard drives has been examined with angle-resolved ESCA. The lubricant partitions itself into thin, presumably monolayer, areas and thicker patches largely impenetrable to the substrate photoelectrons. These thicker regions are at least three times as thick as the monolayer and may correspond to the trilayers detected by surface energy and ellipsometric surface diffusion measurements. Detailed examination of layering within the lubricant shows significant perfluoropolyether (Zdol) backbone and a discernible excess of ether oxygen adjacent to the overcoat surface. The latter results indicate that the inverted-U conformation sometimes sketched for bonded lubricants is an exaggeration for the system examined here. The analysis models include a two-tiered overlayer structure (thin and thick) and a two-slab structure for revealing subtle layering within the thin regions. Current office spreadsheets provide adequate visualization and optimization capability for performing these analyses. (C) 2000 American Institute of Physics. [S0021-8979(00)39308-2].