Photon correlation spectroscopy. See

Using special dispersion techniques it is possible to make dispersions of PAni in several mainly polar solvents and, more recently, in water. The most efficient solvents for dispersing PAni are NMP and DMSO. Such solvents are used by many other groups for dissolving neutral PAni (emeraldine base, EB). We have shown by membrane filtration and by photon correlation spectroscopy (see Section IV.K) that the EB in NMP or DMSO, which are transparent clear blue liquids, are in fact also dispersions and not solutions. 

Obviously, in the case of PS these discrepancies are more and more reduced if the probed dimensions, characterized by 2ti/Q, are enlarged from microscopic to macroscopic scales. Using extremely high molecular masses the internal modes can also be studied by photon correlation spectroscopy [111,112], Corresponding measurements show that - at two orders of magnitude smaller Q-values than those tested with NSE - the line shape of the spectra is also well described by the dynamic structure factor of the Zimm model (see Table 1). The characteristic frequencies QZ(Q) also vary with Q3. Flowever, their absolute values are only 10-15% below the prediction. 

Results from other spectroscopic techniques and photon correlation spectroscopy have been compared for aPP in [126] (see Fig. 4.11). A scaling of the dynamic structure factor at could not be achieved on the basis of the dynamic data reported in [140]. The other temperature dependencies obtained seem to be compatible with the neutron data. Finally, the temperature dependence deduced by Tormala for PIB from the compilation of different spectroscopic data does not agree with the result of the microscopic observation of the structural relaxation (see Fig. 4.9 [125]). 

This section contains a general description of the principles by which the Coulter Model N4 Sub-Micron Particle Analyzer, used in this study to characterize artificial gas-in-water emulsions (see Section 10.4), determines sample particle size. The measuring principles are based on the theory of Brownian motion and photon correlation spectroscopy (ref. 464,465 see also Sections 10.2 and 10.4). 

This molecular argument may explain the earlier-described and repeatedly observed finding with concentrated gas-in-liquid emulsions (see Section 10.4) that, following a period of microbubble growth, the average hydrodynamic diameters (detected by photon correlation spectroscopy) of the microbubble and micellar populations simultaneously decreased. In such situations, microbubble fission may have occurred (following microbubble collision) and the surfactant molecules needed for the expanding... 

Many papers report the fractionation of polystyrene latexes or mixtures thereof, as such commonly available spherical latex standards are an ideal system to test FFF setups or evaluations (for an example, see [362,401]). Recent coupling of Fl-FFF to MALLS enables a very high precision in particle size determinations. One example is shown in Fig. 31, where two Duke standard latex batches of a nominal size of 100 nm were investigated by Fl-FFF/M ALLS, underlining both separation power and resolution. Using traditional techniques such as photon correlation spectroscopy (PCS) and classic Fl-FFF detection, these samples seem to be identical. However, with Fl-FFF/MALLS, the batches could be separated as two discrete size distributions with a peak size that differed by 3 nm. However, it is not stated if a precise temperature control was maintained so that, critically considered, the observed differences could also have their origin in slight temperature... 

PCS = photon correlation spectroscopy = QELS see electromagnetic radiation Pearson s rule 3.185 Peclet number 1.7.97 pendant drop see drop, pendant penetration depth (evanescent waves) [1.7.10.121 period (of a wave) 1.7.4 permeability see porous plugs perpetutd motion 1.2.8 of second kind 1.2.23... 

Table 5.2 Light scattering, photon correlation spectroscopy, viscosity and size-exclusion chromatography data of a fractionated random copolyester (for structure and composition see text) in BTFMP at 60 C [8]... 

Photon correlation spectroscopy has proved in the last decade to be a most versatile method for characterizing macromolecules. Most early measurements were made on macromolecular diffusion, but the technique has also been used to study intramolecular motion of polymers (see ref. 68). A recent paper... 

Dynamic light-scattering, sometimes called quasi-elastic light scattering or photon correlation spectroscopy, can be used to measure the diffusion coefficients of polymer chains in solution and colloids, a kind of Doppler effect see Section 3.6.6. In a dilute dispersion of spherical particles, the diffusion coefficient D is related to the particle radius, a, through the Stokes-Einstein equation. 

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