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Supersonic Cluster Beam Deposition was exploited to study morphology, nanostructure and room temperature spontaneous oxidation of Nickel films obtained by cluster assembling in high-vacuum conditions. Size analysis shows the dominant presence of particles with dimensions below 10 nm, while the lognormal profile of the size distribution confirms that gas-phase homogeneous nucleation and aggregation prior to deposition is at the base of the mechanism governing clusters formation. The relationship between surface roughness and film thickness is found to follow a power law, suggesting a growth process ascribable to ballistic deposition model. Although ultrafine dimensions, clusters oxidation is not complete as residual metallic Nickel, beside NiO and Ni(OH) 2 , is detected by Electron Spectroscopy and observed by Transmission Electron Microscopy and Electron Diffraction, within core-shell structures. Cubic symmetry is identified in both metallic and NiO phases, while hydroxide phase appears as amorphous. The presence of hollow particles is also unveiled, which may represent a first clue of room temperature Kirkendall effect in ultrafine Nickel particles produced by Supersonic Cluster Beam Deposition. The coexistence of core-shell and hollow structures of the same size suggests that particle dimension per-se is not enough to define unambiguously the outcomes of room temperature oxidation process. • Nanostructured Nickel films were produced by Supersonic Cluster Beam Deposition. • Surface morphology unveils ballistic growth mechanism and confirms soft-assembling. • Room temperature spontaneous oxidation generates both core-shell and hollow particles. • Size per-se is not enough to define unambiguously the outcomes of oxidation process. • Freezing of various metastable structures by supersonic expansion might explain this. [ABSTRACT FROM AUTHOR]

Abstract: CdSe nanocrystals (NCs) are synthesized by the single source precursor thermal method. The use of a temperature ramp allows to obtain faster elaboration and smaller nano-particles in size. A cross-disciplinary study between chemical analyses and physical techniques provides consistent data for these small size NCs. Joint mass spectroscopy, transmission electron microscopy and optical spectrometry techniques give a coherent picture about average size and size dispersion of the NCs, as well as their optical spectral response in correlation with their size via quantum confinement effects. [Copyright &y& Elsevier]