Scattering monochromatic light

Raman scattering spectroscopy is used to probe the vibrational excitations of a sample, by measuring the wavelength change of a scattered monochromatic light beam. This is usually performed by impinging a monochromatic laser beam to the sample surface, and by recording the scattered beam spectrum. 

The application of static light scattering to polymers is based on the theoretical equations of Debye (1944, 1947) and the methodology of Zimm (1948). The principles apply equally to polysaccharides (Sorochan et al., 1971). In total intensity light scattering, monochromatic light (436 and 546 nm) at constant T passes through the dispersion and becomes plane polarized the horizontal beam is scattered in accordance with the equation (Hiemenz, 1986)... 

With laser diffraction technology, the particle size distribution is determined on the basis of the scattering monochromatic light (at 750 nm). The measurement of particle diffraction pattern is characteristic of particle size in the range of 0.4 to 2000 ixm of particle diameters [20]. 

The strong scattering of visible light is a characteristic feature of nematic liquid crystals. The scattering can be attributed to thermally induced fluctuations of the director orientation. In principle, the elastic coefficients of the liquid crystal can be determined from the intensity of scattered monochromatic light. The viscoelastic ratio, i.e. the ratio of the viscosity coefficient to the elastic coefficients can be obtained from the line width or intensity modulation of the scattered light [17-22],... 

RS Raman spectroscopy [210, 211] Scattered monochromatic visible light shows frequency shifts corresponding to vibrational states of surface material Can observe IR-forbidden absorptions low sensitivity... 

The essentials of the Raman scattering experiment are shown in Figure 1. An intense monochromatic light beam impinges on the sample. The electric field of the incident radiation distorts the electron clouds that make up the chemical bonds in the sample, storing some energy. When the field reverses as the wave passes, the... 

Another technique widely used to measure the cholesteric pitch is based on the Bragg scattering of monochromatic light (obtained by a helium-neon laser) from fingerprint or planar textures of the cholesteric32 Its angular dependence is strictly related to the cholesteric pitch. 

The variation of scattered light intensity with 0 as typified by Fig. 9.19 clearly becomes more complex as the particle size increases, with sharp oscillations seen at a 10. However, recall that this is for a spherical homogeneous particle of a fixed size and for monochromatic light (e.g., a laser) when the particle is irregular in shape, these oscillations are far less prominent. This is also true for a group of particles of various sizes, that is, a polydisperse aerosol, where the overall scattering observed is the sum of many different contributions from particles of various sizes. Finally, nonmonochro-matic light and fluctuations in polarization also help to smooth out the oscillations. 

Light-Scattering Photometer. In one type, suspended particles are determined (counted). Another type is used to determine the molecular weight of macromolecules dispersed in solution. The former type operates on the basis of a nephelometer the latter is of much higher precision and uses monochromatic light. 

When a transparent medium was irradiated with an intense source of monochromatic light, and llie scattered radiation was examined spectroscopically, not only is light of the exciting frequency, v, observed (Rayleigh scattering), blit also some weaker bands of shifted frequency are detected. Moreover, while most of the shifted bands are of lower frequency, v - Aii, there are some at higher frequency, v + Aiq, By analogy to fluorescence spectrometry (see below), the former are called Stokes bands and the latter a iti-Stakes bands. The Stokes and anti-Stokes... 

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