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Molecular beam epitaxy has been used to grow SrF 2 thin films on Si͑001͒. The growth modes have been investigated by atomic force microscopy, electron diffraction, and photoemission. Two principal growth regimes have been identified: ͑i͒ when deposition is carried out with the substrate held at a temperature of 700-750°C, SrF 2 molecules react with the substrate giving rise to a Sr-rich wetting layer on top of which three dimensional bulklike fluoride ridges develop; ͑ii͒ when deposition is carried out with the substrate held at 400°C, a nanopatterned film forms with characteristic triangular islands. Results are compared to the growth mode of CaF 2 on Si͑001͒ under analogous deposition conditions. Morphological and structural differences between the two systems are associated with the larger lattice parameter of SrF 2 with respect to CaF 2 , resulting in a larger mismatch with the Si substrate.

This work demonstrates how to create the structures Au/GaAs with perfect on-surface gold nanoclusters. In doing so, used is covering the GaAs substrate with chemically stable atomic monolayers of sulphur to prevent subsequently a chemical reaction of Au with GaAs. The structures Au/S/GaAs with monolayers of chemisorbed sulphur atoms are fabricated, characterized and studied by polarized reflection spectroscopy. The anisotropy of on-surface gold nanoclusters is established, and the anisotropic plasmons localized in Au clusters are investigated using the spectra of polarized reflection and interpreted theoretically. Keywords: sulphide passivation, gold nanoclusters, plasmon anisotropy, polarized reflectance.

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