Rayleigh-Debye-Gans theory, 93

Cellulosic nanowhiskers. Theory and application of light scattering from polydisperse spheroids in the Rayleigh— Gans-Debye regime. Biomacromolecules,... 

A rather general approach for determination of the function P(9) was proposed by Rayleigh and further developed by Debye and Gans. The main assumption in the Rayleigh-Debye-Gans (RDG) theory is that the incident beam that excites the electrical dipoles in the particle is not influenced (in either magnitude or phase) by the presence of the particle. This requirement is better satisfied by smaller particles wifh a refractive index close fo fhat of the disperse medium. The respective quantitative criterion reads... 

Rayleigh-Debye-Gans Theory Theory of Mie Interacting Particles... 

FIGURE 5.71 The Rayleigh-Debye-Gans theory is based on the assumptions that (1) the incident beam propagates without being affected by the particles, and (2) the scattered hght, received by the detector, is a superposition of the beams emitted from the induced dipoles in the different parts of the particle. 

Farias, T.L., Koylu, U.O., and Carvalho, M.G., Range of validity of the Rayleigh-Debye-Gans theory for optics of fractal aggregates, Appl. Opt, 35, 6560, 1996. 

T. L. Farias, M. G. Carvalho, U. 0. Koylii, and G. M. Faeth, Computational Evaluation of Approximate Rayleigh-Debye-Gans/Fractal Aggregate Theory for the Absorption and Scattering Properties of Soot, ASME Journal of Heat Transfer, 117, pp. 152-159,1995. 

Throughout this discussion, we have implicitly assumed that the rod is optically homogenous with a single index of refraction and that the Rayleigh-Debye-Gans theory is valid, which basically restricts the theory to thin rods, unless the refractive index of the cylinder is close to that of the solvent used [73]. 

Figure 2.15. Application ranges for various theories (R Rayleigh scattering RDG Rayleigh-Debye-Gans scattering).

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