Interaction of energetic oxygen ions with lithium-containing amorphous hydrogenated carbon films: A mass spectrometry study

Abstract Lithium-containing amorphous hydrogenated carbon coatings ( a-C:H Li ) have been prepared by a modified plasma assisted chemical vapor deposition (rf-PACVD) technique. In order to investigate the interaction of energetic oxygen with these films they were irradiated with oxygen ions of 3 keV energy. Erosion and retention behavior was measured by direct detection of emitted particles using a differentially pumped line-of-sight quadrupole mass spectrometer. Results are compared to those of previous studies on pure and boron-containing carbon materials. Like in these materials, emission of reaction products from a-C:H Li is dominated by CO and CO 2 , to a smaller extent also emission of lithium oxide, Li 2 O, is observed. As compared to pure carbon the emission of reaction products is delayed, and the erosion yield after oxygen saturation of the surface layer is lower for lithium-containing films. Taking into account results of X-ray photoelectron spectroscopy, it can be concluded that the interaction of a-C:H Li with energetic oxygen follows the same general trends as observed for boron-containing carbon materials. However, chemical reactions and their dependence on conditions of irradiation are more complex in a-C:H Li than in boron-containing carbon.