Structure and optical properties of Au-polyimide nanocomposite films prepared by ion implantation

Au-polyimide nanocomposites have been synthesized by implanting different doses of Au+ ions in 100 nm thick films of pyromellitic dianhydride-4,4(') oxydianiline polyimide, prepared by glow discharge vapor deposition polymerization. Unambiguous evidence of Au nanoclusters growth is found only at the highest implantation doses (5x10(16) Au+/cm(2)). Structural, compositional, and optical characterizations show that the implantation induces the compactation of the initial film due to H and C loss. The resulting structure is a composite containing 2-3 nm gold nanoparticles arranged in a layer of about 40 nm and, just beneath the sample surface, a 15 nm thick carbon-rich layer. Optical simulations suggest the presence of a gold-carbon core-shell structure in the nanoparticles.