Scattering from a Solution of Small Particles

In solutions and in mixtures of liquids, additional light scattering arises from irregular changes in density and refractive index due to fluctuations in composition. If the solution is dilute, the density fluctuations are essentially identical to those existing in the pure solvent [9] 

From thermodynamic arguments, Ac2 is related to the chemical potential, jjj. Thus, the excess Rayleigh ratio may be written [9] 

The relation between the chemical potential of the solvent and the osmotic pressure II is 

K is also known as the Debye constant [9], NA is Avogadro s number, and n0 is the refractive index of the pure solvent. 

The osmotic pressure may be written as a power series in concentration [9]. 

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