Small palladium particles with mean diameters ranging from 1.4 to 5 nm have been prepared within a plasma polymer matrix from a vinyltrimethylsilane monomer. Electron dift'raction has shown a decrease of the Pd lattice parameter with decreasing size of palladium cluster. These experimental data are used to deduce the value of the surface stress coefficient f =6.0+0.9 N/m. A contraction of the lattice constant of small palladium particles with decreasing of cluster size, to our best knowledge, has not been reported in the literature up to now. The results suggest that the dilatation of the Pd lattice constant, often reported in the literature, can be explained in terms of incorporation of impurities like carbon, hydrogen, and oxygen, or pseudomorphism in the case of crystalline supports.

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Metal clusters trapped in solid‐state matrices can be produced in various wayas. The new method presented here relies on the simultaneous plasma polymerization of a vinyltrimethylsilane monomer and deposition of metal clusters (e.g., Au, Ag, Pd) by an inert gas evaporation technique. The characterization by TEM, XPS, and UV‐vis and FTIR spectroscopy of amonorphous plasma‐polymer films containing gold clusters is described, which revelas that the clusters areunigorm in size and crystalline.

Metal Clusters in Plasma Polymer Matrices: Gold Clusters.-A novel deposition technique separating the metal cluster source from the plasma discharge region is developed and used for the preparation of gold clusters of 1.4-5.0 nm diameter within polymer matrices from vinyltrimethylsilane and tetraethoxysilane monomers. The polymer-entrapped gold clusters are characterized by HRTEM, XPS, FTIR spectroscopy, and UV/VIS spectrophotometry. This technique can also be applied for the preparation of e.g. Pd, Pt, and Ag clusters. -(LAMBER, R.; WETJEN, S.; SCHULZ-EKLOFF, G.; BAALMANN, A.; J. Phys. Chem. 99 (1995) 38, 13834-13838; Inst. Angew. Phys. Chem., Univ. Bremen, D-28334 Bremen, Germany; EN)

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