DEPOLARIZED RAYLEIGH-SCATTERING IN WATER UP TO SUPERCRITICAL CONDITIONS

Depolarized Rayleigh spectra of water have been measured as a function of density along several isotherms in both liquid and supercritical phases. At all the thermodynamical states the spectral line shape can be fitted by a Lorentzian line superimposed to an exponential background. The behavior of the fitting parameters shows that at temperatures lower than ∼470 K the temperature is the most relevant parameter in determining the dynamics of the system, whereas above this temperature both temperature and density play a relevant role. Both the line shape and intensity of the spectra can be consistently interpreted in the framework of the first-order dipole induced dipole approximation to the collision-induced light scattering. The data show a clear evidence for cancellation effects. © 1995 American Institute of Physics.