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.