METAL-CLUSTERS IN PLASMA POLYMER MATRICES - COLD CLUSTERS

By means of an inert gas evaporation technique in combination with a simultaneous plasma polymerization process, gold clusters with mean diameters ranging from 1.4 to 5 nm have been prepared within plasma polymer matrices from vinyltrimethylsilane and tetraethoxysilane monomers. For the characterization of these materials high-resolution electron microscopy (HRTEM), electron diffraction (ED), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and W-vis spectrophotometry were used. Electron diffraction has shown a decrease of the Au lattice parameter with decreasing size of the gold cluster. The experimental data were used to deduce the value of the surface stress coefficient f = 6.3 +/- 1 N/m. W-vis spectrophotometry revealed a strong blue shift of the plasmon resonance frequency from lambda = 578 nm (D-Au = 5 nm) to lambda = 532 nm (D-Au = 2 nm), In the case of the 1.4 nm clusters, a distinct absorption peak could not be observed. In the case of the plasma polymer matrix from a tetraethoxysilane monomer, a strong chemical damping of the surface plasmon resonance has been observed.