LIGHT SCATTERING FROM REACTIVE FLUIDS .3. INTENSITY CALCULATION

Using standard perturbation theory for degenerate matrices, an expansion for the eigenvectors corresponding to the thermodynamic fluctuation modes in a chemically reactive fluid is obtained. The expansion is valid for small scattering angles, that is, vanishing spatial gradients. These eigenvectors give rather complicated expressions for the intensities of the individual lines, making it rather impractical to get these intensities. We have therefore evaluated partial sums of integrated intensities, which depend only on thermodynamic equilibrium parameters and stoichiometric coefficients. We evaluate explicitly the ratio of the intensity contribution due to the chemical reactions and diffusion processes (Berne-Frisch approximation). For the case of the reaction AB→←A+B, the intensity is proportional to the net change in the dielectric polarizability in the reaction, in accordance with the result obtained by Berne, Deutch, Hynes, and Frisch for a simpler case. Our method is, however, general and can be used for any number of components and reactions.