Light scattering formal solution

Levanyuk has considered a problem identical in substance to the introduction of nonlinear terms in Eq. (24). He examined the theory of light scattering at order-disorder transition points according to the formalism of Landau and Lifshitz. In that formalism / g does not vanish, and he concluded that the Ornstein-Zernike theory is inadequate at temperatures sufficiently close to Tj. This, of course, is what has been found here, if m = 3. An actual prediction in this case would require numerical solutions of Eq. (28). 

Equation 1.15 may be regarded as the defining equation for the parameter y, since Ago can be evaluated by use of such standard techniques as osmotic pressure, light scattering, and sedimentation equilibrium. In the classic FH theory, y is taken as the strength of the polymer-solvent interaction. However, in the Koningsveld-Staverman formalism, it has no such meaning but is an empirical function which absorbs all the deviations of Ago in an actual quasibinary solution from that in the reference FH solution. 

Since then, attempts have been made to improve and modify Debye s (1959) theory of critical opalescence. Vrij and van den Esker (1972) have accounted for the influence of local concentration gradients on the entropy term of the friee energy F in their consideration of light scattering from moderately-concentrated polymer solutions in terms of Silberberg s (1952) model (recall that Debye allowed for their influence on the entropy term only). To calculate the scattering intensity 7, they used the Fourier transformation of the concentration fluctuations and Brillouin (1922)-Debye s (1959) formalism... 

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