Effect of light scattering

In order to study the mobility of elements of crosslinked structure of CP, it is suitable to use their microdisperse forms [30-35]. On the one hand, in potentiome-tric titration the equilibrium is quickly attained for these forms and on the other hand the effect of light scattering in spectral methods of investigation (e.g., polarized luminescence) can be greatly decreased. 

The effect of light scattering and absorption by atmospheric constituents on the intensity and wavelength distribution of sunlight at the earth s surface depends on both the nature and concentration of the gases and particles as well as the path length through... 

Figure 11.28—Effect of light scattering on a spectrum recorded in absorbance and on its derivative spectrum. This figure shows a comparison of the derivative spectra corresponding to the spectrum A of a compound in solution without scattering and to the same spectrum B in the presence of scattering. It can be seen that the effect of scattering is in the order of 10% in absorbance units but only about 1% in the derivative spectrum (modelled spectra).

Atomic fluorescence, since it makes use of ground state atoms for the analytical process, is much less temperature dependent than is flame emission. It is similar to atomic absorption in this respect. Atomic fluorescence is more subject to quenching effects than is flame emission. The effects of light scattering in atomic fluorescence can be a problem, although means to minimize this effect are available. 

Water resistant, front-surface aluminum mirrors can be used as deposition substrates, followed by spectral acquisition in the R-A mode. The smooth and hard surface properties of mirrors complicate efficient analyte deposition (spreading of the analytes) when the eluent is not completely evaporated. The spectral data recorded from these substrates should be in close resemblance to the spectra obtained from transmission measurements, because the band intensities are controlled by a double-pass transmittance mechanism. However, still spectral differences between R-A and KBr disk spectra can be observed, including absorption-band shifts and asymmetries. Furthermore, the effect of light scattering (Christiansen effect) may become apparent when the spot thickness exceeds a certain level and anomalous relative band intensities may be observed in R-A spectra of certain analytes deposited on flat substrates when compared to transmission spectra acquired from KBr disks. In order to minimize these... 

The effect of light scattering is characterized by several quantities Fis, t, etc., which can be expressed through different parameters of the system the dielectric constant t, the polarizability a, the refreictive index //. Moreover, the polarization of incident light beam may be of different character. 

The need to grind the sample down to particle sizes of below 1 pm is important to reduce or eliminate the effects of light scattering (Fig. 2). Time taken on the preparation of a pellet is usually time well spent. A poorly prepared pellet will usually provide low transmission and even a distorted spectrum (if the sample is not adequately ground). 

M. Manley, A. E. J. McGill, B. G. Osborne. The effect of light scattering on NIR reflectance and transmittance spectra of wheat. J Near Infrared Spectmsc 2 93-99, 1994. 

L. Mandelstam, G. Landsberg, A novel effect of light scattering in crystals. Naturwissenschaften 16, 557 (1928)... 

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