C. Vasi

Structural properties of micellar solutions

Abstract The results of a small angle neutron scattering experiment are reported in which the structural properties of a novel water/AOT/cyclohexane reverse micelle system is investigated. The metallic ions bound to AOT are Al 3+ and Zn 2+ . Spectra were collected at different water contents and at the maximum surfactant concentration. A quantitative evaluation of the shape and size of the droplets formed is performed, and a comparison among similar shapes is presented.

Raman spectroscopic and low-temperature calorimetric investigation of the low-energy vibrational dynamics of hen egg-white lysozyme

The low-frequency vibrational dynamics of chicken hen egg-white lysozyme were investigated using Raman spectroscopy and low-temperature calorimetry. An amorphous-like behaviour of low-frequency dynamics was observed in this protein. By using inelastic light scattering data and resorting to a fitting procedure, the low-temperature specific heat trend was theoretically reproduced, confirming that, as in disordered systems, the same low-energy excitations give rise to the observed anomalies in low-frequency vibrational and low-temperature thermal properties. A further study of polarised and depolarised Raman spectra has allowed us to infer information about the symmetry of these modes. The frequency dependence of the light–vibrational coupling constant has also been analysed.

Low-frequency Raman scattering of silver borate glasses

The vibrational dynamics of Ag2O–B2O3 glasses has been investigated by Raman spectroscopy in the frequency region below 200 cm−1. The spectra show the presence of the boson peak (BP), whose shape and frequency location are almost independent of the silver concentration. The increase in the sound velocity with increasing Ag+ content testifies to the progressive stiffening of the borate skeleton and refers to the existence of acoustic modes with increasing frequency. Consequently it is believed that the vibrational modes mainly contributing to the BP have a localized character and are decoupled from the acoustic phonons. An interpretation of these experimental observations ascribes a significant role in the evolution of the low-frequency vibrational dynamics of these glasses to the local vibrations of Ag+ ions.