Polarization intensity differential scattering

Droplet size analysis was used for characterization of the emulsions just prepared and to detect alterations of emulsions during storage. The analysis was conducted using laser diffraction with polarization intensity differential scattering (PIDS) technology (Coulter LS 230, Beckman-Coulter, Krefeld, Germany). 

This combined approach is known as the polarization intensity differential scattering (PIDS) technique [4,5,6],... 

Bott, S. E., Hart, W. H., Particle Size Analysis Utilizing Polarization Intensity Differential Scattering, US Patent 4,953,978, 1990. 

The dependence of the radiation pattern from dipoles uniformly distributed within a spherical particle of relative refractive index m = n /n2 = 2.0 upon the particle size is illustrated in Fig.4.9 where the angular distribution in the scattered intensity is plotted in arbitrary units for different values of the size parameter. The exciting radiation incident upon the particle is assumed to be horizontally polarized. There is a sharp increase in the differential scattering... 

Phenomena related to circular dichroism which may be useful for studying conformations in polymers are the circular intensity differential (CID) for scattered light. The difference in scattered intensity is measured for left and right circularly polarized incident light. At this time these effects have only been reported for small molecules. In principle, however, they may be very useful for the study of polymers. 

We have been discussing electronic transitions and ultraviolet or visible circular dichroism. However an optically active molecule will also have infrared CD due to its vibrational transitions. The measurement of infrared CD is very difficult, but some data exist [29]. Another related measurement is the Raman circular intensity differential [30]. It is the difference in Raman scattered intensity when right and left circularly polarized light is... 

Relevant quantities of interest, e.g. differential scattered intensities A/, are obtained from the formulae in Table 1 by an appropriate choice of K. The difference between the intensity of right (R) and left (L) circularly polarized scattered light in a backscat-tering SCP experiment with unpolarized (u) exciting light from Equation [8] is... 

Calculated depolarization ratios and differential scattering cross sections (do/dn)i for propyne are presented in Table 9.10. The simulated Raman spectrum is compared with the experimental gas-phase spectral ciuve [317] in Fig. 9.4. The band half-widths are taken from the experiment. The lines of A] transitions have sharp features, while E-vibrations are characterized with much broader bands. Since no quantitative intensity data for this molecule exist, a qualitative assessment of the results obtained can be done only. Fig. 9.4 reveals that the overall shape of the Raman spectrum is reproduced correctly. The most intense Raman lines are calculated to be those positioned at 2941, 2142 and 930 cm with intensities decreasing in the same order in agreement with the experimental spectrum. These lines are highly polarized. The other vibrational transitions giving rise to low- or medium-intensity lines in the spectrum are predicted to have intensities of the same order. The most significant difference between calculated and... 

One of the main goals of the crossed-beam experiment is to measure the internal energy AEvlh rol transferred to the molecule. In principle, this is possible in either of two ways. First, the scattered molecules could be detected and their product-state population analyzed. Infrared emission or absorption techniques may be considered, similar to those used in cell experiments.13 21 Although such studies would lead to the most detailed results (at least for polar molecules), under crossed-beam conditions they are impossible for intensity reasons, even if the possibility of measuring differential cross sections is renounced and the molecules in the scattering volume itself are detected. Detection via electronic molecular transitions may be invisaged. Unfortunately, the availability of tunable lasers limits this possibility to some exotic molecules such as alkali dimers. The future development of UV lasers could improve the situation. Hyper-Raman... 

For comparison with experimental data it is more suitable to state relative intensities in terms of differential cross sections, since these are proportional to the relative intensities obtained in the experiment. The Q-branch differential cross section for a scattering angle of 90° and an incident light beam which is plane polarized perpendicular to the scattering plane is... 

The first prerequisite for measurement of photoelectron spin-polarization is the ability to separately detect the photoelectrons ejected from the different fine-structure levels (e.g., 2n3/2 and 2n1/2 for HX+ X2n). When the molecule contains a heavy atom (e.g., large spin-orbit splitting), it becomes easier to use the electron kinetic energy to distinguish the photoelectrons ejected from the different fine structure channels. For spin-polarization analysis, the accelerated electron beam (20-120 keV) can be scattered by a thin gold foil in a Mott-detector. The spin-polarization is determined from the left-right (or up-down) asymmetry in the intensities of the scattered electrons (Heinzmann, 1978). Spin polarization experiments, however, are difficult because the differential spin-up/spin-down flux of photoelectrons is typically one thousandth that obtained when recording a total photoionization spectrum. 

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