Knowledge Bank

Effects of viscosity and temperature on the scattering caused by fluctuations of optical anisotropy in liquid carbon disulfide and in liquid mixtures of carbon disulfide and carbon tetrachloride has been investigated by observing scattered light near the $4880\backslash AA$ line from an $Ar+$ laser. In pure $CS2$ at $293\circ K$, the line shape close to the incident frequency is Lorentzian with a half-width of $5.6cm-1$. The half-width has been found to be proportional to the temperature divided by the viscosity of the liquid whereas the total scattered intensity appears to be constant as a function of temperature. From the half-widths of the scattered radiation, relaxation times for the reorientation of molecules in an a.c. electromagnetic field have been calculated. These half-width measurements agree with the simple picture of $Debye1$ for orientational scattering in an electromagnetic field. In addition the measured line shapes and polarization effects are in agreement with the predictions of $Leontovich.2$