ARXPS investigation of diffusion as a limiting process in the incorporation of adatoms into polystyrene surfaces treated by nitrogen plasmas

摘要

Polystyrene films were exposed to nitrogen plasmas for periods up to 4 min. ARXPS measurements revealed the presence of oxygen and nitrogen in the surface because of the plasma treatment. The depth profiles of these adatoms were determined by fitting a Thomas-Windle model profile to the data. As found previously, the best-fit depth profiles resembled a step function, consistent with case II diffusion. However, the depth of penetration of the adatom species into the polymer surface was not found to vary with plasma duration, which is inconsistent with Case II diffusion, and provides evidence that diffusion processes do not limit the loading of adatom species into the surface during nitrogen plasma treatment. A possible reason for the generation of erroneous step function depth profiles is discussed. Copyright (c) 2007 John Wiley & Sons, Ltd.