Spectral Analysis of Light Scattered from Fluids

The normal-mode decomposition of the spectral densities which play a role in the analysis of light-scattering spectra of fluids is treated. The inherent symmetry of the hydrodynamic matrix and the relative magnitude of its elements are utilized to develop a simple and systematic method for obtaining the eigenvalues and the required eigenvector elements. The scheme, which involves a partitioning of the hydrodynamic matrix, is shown to yield the eigenvalues correct up to terms of order $k^2$ and the eigenvectors correct up to terms of order $k$. The method is illustrated by application to a two-component fluid.