Critical Opalescence: The Rayleigh Linewidth

Publisher Website
Google Scholar
Abstract
Debye's derivation of the Ornstein—Zernike modification of Einstein's theory of critical opalescence is reviewed. It is shown that Debye's free‐energy function leads to a modification of the Landau theory for the width of the Rayleigh line which is equivalent to the results of Fixman, Botch, and Felderhof. This equivalence is utilized to predict the magnitude of the departure of Rayleigh linewidths from the Landau prediction by comparison with the results of angular‐scattering intensity measurements. It is thus shown that in light‐scattering experiments, pure fluids should obey the Landau theory quite accurately, whereas critical mixtures should show significant departures from the Landau prediction.