Intensity distribution, light scattering

Data Transformation. The raw size distribution obtained in PCS is intensity weighted. Most particle sizing results are either mass, area, or number weighted. Therefore, to compare results, the PCS measurements would have to be transformed. If the ratio of the concentrations in each peak is desired, then a transformation is also necessary. The intensity of light scattered by a sphere is given by... 

The angular intensity distribution of scattered light l 9,n) at angle 6, for particles of diameter d and refractive index fi is given by Mie scattering theoiy. For a polydisperse distribution ... 

The spacial distribution of intensities of light scattered by disperse system (Fig. V-19) can thus be described by the surface of rotation of sin2(p function around the (p=0 axis (bagel without a hole). The cross-sections of this surface by planes yield indicatrixes of the scattered light. 

To determine the concentration of the dispersed particles, one often replaces ordinary ultramicroscope with fl o w u ltr am icroscope designed by B. Derjaguin and G. Vlasenko [42], In the flowing suspension this device registers the number of particles that travel per unit time across the microscope field, allowing one to rapidly determine the particle concentration in sols. The use of optical electronic devices for the measurement of intensity of light scattered by individual particles makes it possible for one to obtain also the particle size distribution curves. 

Figure 7. Normalized light scattering intensity distribution with scattering angle in the case of absorptive extra-cellular medium. Cell parameters are the same as for Fig. 5, except a non-zero imaginary part of the refractive index of the extra-cellular medium k = 0.05.

Total Internal Reflection Microscopy serves, e.g., for obtaining the height distribution function between an - in most cases spherical - object and a surface from quantitative, time-resolved measurements of the intensity of light scattered within the evanescent wave. From the height distribution function one might find the interaction energy between object and surface. 

Figure 2.3 Numerical analysis of a nano-light-source generated by a metallic nano-tip. (a) Model for numerical analysis, (b) Intensity distribution of light scattered by the metallic nano-tip.

The vesicle size is an important parameter not only for in-process control but particularly in quality assurance, because the physical stability of the vesicle dispersion depends on particle size and particle size distribution. An appropriate and particularly quick method is laser light scattering or diffraction. Laser light diffraction can be applied to particles > 1 pm and refers to the proportionality between the intensity of diffraction and the square of the particle diameter according to the diffraction theory of Fraunhofer. 

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