Paper PS-TuP1
Steady-State and Transient Hydrocarbon Production, and Retention in a-C:D Thin Films by Low Energy Impact Atomic and Molecular Deuterium Projectiles

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

We report production yield of methane and heavier hydrocarbons for deuterium atomic and molecular ions incident on a-C:D thin films in the energy range 10-200 eV/D. the yields were determined at sufficient accumulated ion beam fluences that steady-state conditions were reached. In addition to steady-state chemical sputtering yields, we have studied transient hydrocarbon production, re-emission and retention of hydrocarbons from pre-loaded sample surface immediately after the start of beam irradiation. When the surfaces were prepared by irradiation to saturation with lower energy deuterium beams, transient hydrocarbon and re-emission yields significantly larger than steady-state values were observed, which exponentially decayed as function of beam fluence. The initial yield values are related to the starting hydrocarbons and deuterium densities in the prepared sample; while the exponential decay constant provide information on the hydrocarbon kinetic release and detrapping cross sections. Interestingly, this transient effect when ion bean is on can be used to determine experimentally the retention hydrocarbon concentration in amorphous deuterated carbon films after low energy ion beam impacts.