Using the four-photon polarization spectroscopy we have studied the Rayleigh wing spectral patterns of several aqueous salt solutions within the 0-50 cm-1 frequency range. Within the framework of an approach allowing a representation of the Rayleigh wing spectrum as two Lorentzian functions, characterized by the long and the short times of relaxation of an anisotropic mode, we obtained that the short relaxation time does depend on the concentration of electrolyte and its type, whereas the long relaxation time does not. The effect can be qualitatively interpreted supposing that the fluctuations of ionic concentration give rise to the fluctuations of local electric field. An instantaneous magnitude of this field is about 104 V/cm and its time of changing is about 10-12 s. This electric field initiates local microscale Kerr-effects thus contributing to the fluctuations of optical anisotropy, which accounts for an additional depolarized scattering.
Print ISSN: 0942-9352
Volume: 214, 03/2000
Pages: 269