Polarised light, scattering

Note 3 Chiral nematic mesophases exhibit Bragg scattering of circularly polarised light at a wavelength proportional to the pitch P (Xr = P, where is the mean refractive index). 

As we shall see, the intensity, polarisation and angular distribution of the light scattered from a colloidal system depend on the size and shape of the scattering particles, the interactions between them, and the difference between the refractive indices of the particles and the dispersion medium. Light-scattering measurements are, therefore, of great value for estimating particle size, shape and interactions, and have found wide application in the study of colloidal dispersions, association colloids, and solutions of natural and synthetic macro-molecules. 

Figure 3.6 Radiation envelope for light scattered from small particles. Distances from the origin of the dotted, dashed and smooth lines represent the relative intensities of the horizontally polarised component, vertically polarised component and total scattered light, respectively...

Since the light scattering method yields the mass-average molar mass, hence a may be written as cNAyJ Mni. Combining Eqs. 5.47 and 5.50 and assuming that the polarisability of the solvent, a0 is negligible, we obtain... 

The role of exchange scattering can be observed most clearly when polarised electrons are scattered from a target of polarised light atoms. If one observes a spin-flip process like... 

Fig. 1. Experimental set up (90° collection optics) for the measurement of laser Raman scattering, illustrating the definition of the depolarisation ratio. ly and Ij are the intensities of light scattered, respectively, parallel and perpendicular to the polarisation of the incident exciting beam...

Unpolarised light of intensity /o can be represented by the sum of two mutually perpendicular plane polarised beams of equal intensity (/o/2). Consequently, by combining the effects shown in Figures 7.4(a) and (b), the light scattered from unpolarised light and observed in the horizontal plane is the sum of contributions from the vertically and horizontally polarised components ... 

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