IQENS - Dynamic light scattering complementarity on hydrogenous systems

This paper deals with two comparative studies of dynamic light scattering and incoherent quasi-elastic neutron scattering (IQENS) on hydrogenous systems, namely polymeric aqueous solutions and alcohols. In the first topic, attention is focused on the peculiar hydration processes present in poly(ethylene oxide) aqueous solutions and their influence on translational diffusive properties. Dynamic light scattering shows that water behaves as a Boon solvent and furnishes the temperature evolution of the hydration number. IQENS, on the other hand, reveals the presence of entangled water and evidences the effects of H-bond on the diffusive motions. The second topic concerns the study of rotational diffusion in two isomeric alcohols, normal-pentanol and 2-methyl-2-butanol. The comparison of the relational relaxation times, obtained by IQENS and light scattering, allows to separate the self particle contribution from the collective one. The results allow, following Angell's classification, to attribute a more fragile character to the tertiary isomer and a stronger one to the primary alcohol.