Separate dynamics of solute and solvent in water-glucose solutions by depolarized light scattering

We report depolarized light scattering measurements of water-glucose solutions in a wide spectral range from 0.01 to 1000 cm(-1), performed by the combined use of a double monocromator and a multipass Fabry-Perot interferometer. For the first time evidence is given of a low frequency relaxation process related to the glucose dynamics well separated from that of water. This low frequency process has a different origin with respect to the broad relaxation feature detected by dielectric spectroscopy and is interpreted in terms of Stokes-Einstein-Debye rotational diffusion of single glucose molecules. (c) 2007 Elsevier B.V. All rights reserved.