Spectral characterization of perfluoropolyethers lubricant irradiated by laser light

We have investigated the molecular structure change of laser irradiated perfluoropolyether lubricant on disk media by using mass spectroscopy. A KrF excimer laser with a wavelength of 248 nm was used to irradiate the lubricant film (2 nm) on carbon overcoat surface. We found that two unique mass peaks emerged from the laser irradiated lubricant mass spectra, which are attributed to OH-CHF-O(:H+)-CHF-OH and F-COO-CF2-CF2-CF2-CF2+, respectively. With laser fluence increases up to 100 mJ/cm2, these two unique mass peaks start enhancing drastically while the abundance of the end-group of the lubricant, CF2CH2OH, remains almost constant, indicating that the two unique species are generated from the scission and re-arrangement of the backbone ether chains. With laser fluence beyond 140 mJ/cm2, the disk media surface damage is observable and the lubricant evaporation is the main pathway