Transmission electron microscopy and optical characterization of nano-particles

Some of the capabilities of Transmission Electron Microscopy (TEM) in the field of the structural characterization of metal clusters, with dimensions in the nanometer range, are here presented. Three main area of interest are concerned, i.e., measurements of the variation in the lattice parameter as a function of the size decrease by means of electron diffraction; darkfield investigations on the reduction of the melting point; high-resolution study of the dynamic behaviour (instabilities) of the clusters. Optical reflectivity measurements are shown to give useful additional information on the systems here investigated: in particular, the presence of a super-cooling effect and of a hysteresis cycle on going from heating to cooling is evidenced