Reduced scattering intensity

Light Scattering Experiments. This discussion is concerned only with elastic light scattering (24). In these experiments one measures the reduced scattering intensity (sometimes called the Rayleigh ratio) R(0), where... 

It is convenient to lump a number of these parameters into the reduced scattering intensity / , which is defined for unit volume of a scattering solution as... 

Polyelectrolyte Behavior. Figure 1 shows the characteristic Kc/R vs. c plot of lonomers in polar solvents the reciprocal reduced scattered intensity rises steeply from the intercept at zero polymer concentration, bends over, and becomes nearly horizontal at higher concentration. This type of behavior was reported for some salt-free polyelectrolytes in aqueous solution (23.26), although the reliability of these early measurements is rather poor because of very small scattered intensity from polyelectrolyte/aqueous solution systems. For example, the excess scattered intensity from salt-free sodium poly(methacrylate) in aqueous solution over that of water was only 10 to 100% (2i) - (0.1-1) x 10 °. in ionomer solutions,... 

Reciprocal reduced scattered intensity at zero angle, for S-xSSA-Na (M 400,000) of various ion... 

Figure 6. Reciprocal reduced scattered intensity at zero angle, Kc/Rg, against polymer concentration for S-xSSA-Na (M 400,000) in THF. (Reprinted from ref. 18. Copyright 1988 American Chemical Society.)...

Equilibrium Molecular Parameters. Polyelectrolyte effects, evidenced by increased solution viscosity and reduced scattering intensity at very low concentrations, were observed for polyamic acid solutions in NMP which had not been redistilled over P2O5. We attribute this effect to the abstraction of protons from the amic acid by amine impurities in the NMP. This is discussed in more detail in an earlier study (6). Measurements reported by other workers in other amide solvents such as dimethylacetamide, have been made with LiBr added to suppress the polyelectrolyte affect (3). Measurements described here were made on solutions in NMP which had been redistilled over P2O5 > and no polyelectrolyte effects were observed. 

According to the description by Tanford [17], the measured quantity called the reduced scattering intensity in LALLS is expressed in equation (1),... 

If we make use of a high sensitive LALLS photometer equipped with a flowthrough type cell having a small Internal volume, we can continuously record the reduced scattering intensity. Re, as the output of the photometer. 

Figure 5.2 Plot of reduced scattered intensities, Kc/AR, against the compound variable sin (0/2) + kc. Analysis of these data yields the molecular weight M, the osmotic second virial coefficient Aj, and the mean-squared radius of gyration ...

In light-scattering investigations, one measures the reduced scattering intensity at a scattering angle 0,sometimes simply referred to as Rayleigh s ratio, which is defined as [27] ... 

Instrument calibration can be accomplished by using pure liquids, solutions and colloidal dispersions. Among them, pure liquids with known reduced scattering intensity / e, such as benzene, are the most commonly employed standards. Detailed procedures for filtration and calibration methods are described in ref. 27. Data on Rq of several pure liquids, such as benzene, were collected by Kratochvil et al. [34] for incident light wavelengths of 436 and 549 nm and by Pike et al. [35] for an incident light wavelength of 633 nm. 

Fig. 14 Reciprocal diflusion coeflBcient D (q) left scale) and the reduced scattering intensity (right scale) as a function of sin 9/2 with 0 the scattering angle for the proteoglycan monomer (M, 1.6 X 10 g/mol) at Cp = 0.1 g/1 in salt-free solution. (Taken from [133])...

Fig. 19.2. Reciprocal reduced scattered intensity as a function of polymer concentration for S-PS (Mw 400 000) of various ion contents in THF (from Ref. [30])...

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