Long-Range Correlation Length and Isothermal Compressibility of Carbon Dioxide Near the Critical Point

Abstract

We have measured the angular dependence and total intensity of light scattered by carbon dioxide near its critical point, shown that the Ornstein-Zernike theory is inadequate, and determined the temperature dependence of the isothermal compressibility ${K}_{T}$ and the long-range correlation length $\ensuremath{\xi}$. The exponents describing the divergences of ${K}_{T}$ and $\ensuremath{\xi}$ above the critical temperature are $\ensuremath{\gamma}=1.219\ifmmode\pm\else\textpm\fi{}0.01$ and $\ensuremath{\nu}=0.633\ifmmode\pm\else\textpm\fi{}0.01$, respectively. The exponent describing the departure from the Ornstein-Zernike theory is $\ensuremath{\eta}=0.074\ifmmode\pm\else\textpm\fi{}0.035$.