In the recent years it has been generally accepted that seismic parameters add an important observational constraint for the study of stellar populations and galaxy evolution. Padova-Trieste (PARSEC) evolutionary tracks are widely used to characterise stellar objects and stellar populations. Stellar models at the base of these studies suffer from uncertainties and, more important, degeneracy among different input parameters: stellar mass, chemical composition, central chemical mixing, age, etc. Adding seismic properties to the classic parameters for stars at different evolutionary states, from the H main-sequence to the asymptotic giant branch, is a powerful tool to calibrate physical processes in stellar models, and hence to improve our interpretation of Galactic and extra-Galactic observations.

Stars are massive resonators that may be used as gravitational-wave (GW) detectors with isotropic sensitivity. New insights on stellar physics are being made possible by asteroseismology, the study of stars by the observation of their natural oscillations. The continuous monitoring of oscillation modes in stars of different masses and sizes (e.g., as carried out by NASA's Kepler mission) opens the possibility of surveying the local Universe for GW radiation. Red-giant stars are of particular interest in this regard. Since the mean separation between red giants in open clusters is small (a few light years), this can in principle be used to look for the same GW imprint on the oscillation modes of different stars as a GW propagates across the cluster. Furthermore, the frequency range probed by oscillations in red giants complements the capabilities of the planned eLISA space interferometer. We propose asteroseismology of red giants as a novel approach in the search for gravitational waves.

BOOMERanG has recently resolved structures on the last scattering surface at redshift ˜ 1100 with high signal to noise ratio. We review the technical advances which made this possible, and we focus on the current results for maps and power spectra, with special attention to the determination of the total mass-energy density in the Universe and of other cosmological parameters.

Semiconducting iron silicide dots with dimensions ranging between 5 and 100 nm can be obtained by ion implantation on Si wafers and exhibit interesting photo- and electro- luminescent properties.

In our study we use structural and optical characterization as well as theoretical modelling in order to: i) discriminate among intrinsic effects of FeSi2 dots and effects due to lattice damage and Si matrix; ii) identify the range of physical parameters (size, phase, electronic structure) corresponding to the luminescent dots.

Combined TSC and PICTS measurements have been used to determine the activation energies (Et) and capture cross-sections (σ) of the trap levels inside the bandgap of CVD diamond in the energy range 0.4−0.7 eV. High temperature TSC analysis has been performed to determine the trap parameters in the energy range from 0.9 to 1.3 eV. A fieldmap in the Et−σ plane has been obtained from the combination of the TSC and PICTS data depicting the regions corresponding to two isolated trap levels and to a continuous distribution of states. The concentrations of defects have been calculated from the TSC signals and the measurement of the charge collection efficiency of the diamond samples.

The kinetics of the C49-C54 polymorphic transformation in titanium disilicides thin films grown on amorphous Si substrate has been followed by sheet resistance and Infrared Spectroscopy measurements on both blanket samples and submicron lines. The transformation of a fine grained C49 films (davg=30 nm) into the C54 phase was complete after annealing for ∼300 s at a temperature of 700 °C in blanket samples and of 730 °C in submicron lines. The Avrami exponent decreases from n=3 in blanket films to n=l in stripes. The transformation time at a given temperature increases with decreasing linewidth in agreement with the nucleation density model. Infrared Spectroscopy shows no shift of the peaks of the C49 phonons going from blanket to patterned films, suggesting the lack of strain on TiSi2 patterned films. The different behavior between blanket and laterally limited samples has been explained in terms of the different surface energies.

A series of fine grained C49 thin films were prepared by depositing Ti films on heated amorphous as well as crystalline silicon substrates.

Rapid thermal processing at temperatures between 700 and 775 °C was used to transform the metastable C49 phase into the stable C54. The evolution of the film structure and morphology during the transformation was investigated by sheet resistance, optical spectroscopy, diffuse reflectance and AFM measurements. One structural model which could account for our data is proposed according to crystallographic information present in the literature.

We present preliminary results of tight binding molecular dynamics (TBMD) simulations concerning the thermal effects on the structural and electronic properties of GaN. We derived a semiempirical tight binding (TB) potential which is able to reproduce the band structure and the phase diagram of GaN for zincblende, wurtzite and rock-salt phases. We have found that even at few hundreds K above the experimental melting temperature the local ordering is fairly well conserved, with the fraction of wrong bonds quite low. Defects states appear in the gap at approximately 2.3 eV in agreement to the experimental indication for annealed films.

In a theoretical search for new hypotetical sp3-bonded carbon structure containing five-fold rings as a possible result of fullerene transformation under pressure, we have found a triclinic form of diamond with 16 atoms per unit cell which we called tcl-16. We have calculated the ground state structure, the cohesive energy, the bulk modulus and the electronic density of states by means of tight binding molecular dynamics (TBMD). Finally we have compared the phonon spectra at F to existing Raman data for a non-cubic- phase of diamond.

We investigate the short-range structural properties of a-GaAs as obtainedin a computer experiment based on a tight-binding molecular dynamicssimulation. The amorphous configuration is obtained by quenching a liquidsample well equilibrated at T=1600 K. A detailed characterization of thetopology and defect distribution of the amorphous network is presented anddiscussed. The electronic structure of our sample is calculated as well.Finally, we discuss the reliability and transferability of the presentcomputational scheme for large-scale simulations of compound semiconductormaterials by comparing our results to first-principles calculations.