• Study of the morphology of room temperature ionic liquids (RTIL) and their binary mixtures.
The structural complexity is presently considered as the leading factor for many of the specific properties of room temperature ionic liquid (RTIL). Recently obtained results highlighted the existence of structural heterogeneities in these materials, associated to the occurrence of nano-segregation – the formation of nanometric domains. The role played by different chemical details (such as anion nature, alkyl chain length, hydrogen bonding existence) and the different physical parameters (temperature, pressure, confinement) is the topic of our structural studies. X-ray and Neutron diffraction patterns are collected at the EDXD home facility and at Synchrotrons (ESRF, Elettra) and at Neutron Scattering Centers (ILL, ISIS, BENSC), respectively. The collection of the diffraction spectra runs parallel to molecular dynamics simulations aiming to understanding inter and intra molecular correlations.
• Study of the relaxation dynamic of neat RTIL and their mixtures.
It was found, that dynamical properties of the RTIL are strongly correlated to the structural heterogeneity. We investigate the dynamical properties of the ionic liquid with a variety of spectroscopic techniques to obtain detailed information about the role played by various parameter (alkyl chain length, anion type, additive concentration, etc.) The high frequency vibrational mode and low frequency collective relaxation modes are investigated by means of Raman spectroscopy. The dielectric measurements provide the information of dipolar relaxation and ionic diffusion. Quasi elastic neutron scattering data deliver the information about local and diffusive dynamic. By taking advantage of the possibility of selectively deuterating different cation portions we can probe the motions of the specific portions of molecule. Inelastic X-Ray Scattering allows to access to a complementary dynamic range (Q,w) as compared to other techniques, providing a fundamental information to rationalise the collective dynamics in RTIL.
• Study of the dynamical evolution of the structural correlations in amorphous systems, such as glasses and polymers.
The microscopic dynamics of number of inorganic glasses and polymers have been studied around glass transition. Combining the information from different Neutron Scattering Experiments (such as NSE, TOF, Back scattering) we were able to describe the dynamics on the large time- and Q- scale. Our results contributed to the generalization of correlation between the fragility and relaxation scenario in the glassy systems. Rationalizing the Neutron diffraction data of atactic polypropylene (DaPP) as a combination of elastic and inelastic scattering, we highlighted the dynamical nature of the structural evolution: with increasing temperature, cooperative strongly correlated atomic motions take place on the picoseconds time scale. Thus above glass transition the system appears to be better organized that in "frozen" stage and this leads to the anomalous increase of the intermolecular peaks amplitude.