Scattering of light intensity

The intensity of light scattering, 7, for an isolated atom or molecule is proportional to the mean squared amplitude... 

It is awkward to use two different angles to describe the intensity of light scattered along a particular line of sight, but this situation is easily remedied by referring back to Fig. 10.5. It is apparent from Fig. 10.5 that r cos 0 is the projection of r along either the x, y, or z axis, depending on the choice of 0. We therefore see that... 

Next let us consider the light scattered by liquids of low molecular weight compounds. We are actually not directly interested in this quantity per se, but in scattering by solutions-polymer solutions eventually, but for now solutions of small solute molecules. The solvent in such a solution does scatter, but, in practice, the intensity of light scattered by pure solvent is measured and subtracted as a blank correction from the scattering by the solution. 

W. Brown, R. Johnsen, P. Stilbs, B. Lindman. Size and shape of nonionic amphiphile (Ci2Eg) micelles in dilute aqueous solutions as derived from quasielastic and intensity of light scattering, sedimentation and pulsed-field-gradient nuclear magnetic resonance self-diffusion data. J Phys Chem 87 4548-4553, 1983. 

In one method the intensity of the primary beam is diminished by several orders of magnitude through the use of a series of neutral filters, the percentage transmission of each at the wavelength X having been accurately measured. Comparison of the intensity of light scattered by the solution with the intensity of the incident beam meas-... 

Intensity of light scattered at the angle by a solution containing N particles in a volume V (Chap. VII). 

Additional evidence for silica nucleation on biopolymer macromolecules was furnished by experiments in which solutions of proteins were studied by dynamic light scattering. As an illustration, Figure 3.6 shows the relative intensity of light scattering versus the diameter of the scattering particles in solution with 1 wt.% of bovine serum albumin. Curve 1 presents the initial state where the protein was not yet treated with silica precursor. The measured... 

Moreover the ionisation of the electrolyte groups adds to a number of unusual effects in the presence of small amounts of added salt. The intensity of light scattering decreases due to the ordering of the molecules in solution and the Osmotic pressure and ultracentrifugation behaviour are determined predominantly by the total charge on the molecule. 

Turbidity is caused by any solid material which is dissolved or suspended in a liquid. The intensity of light scattered by a sample is measured and compared with that measured for standard formazin suspensions, and expressed as nephelometric turbidity units (NTU). Colour is determined as the absorbance (measured spectrophotometrically at 400 nm) of the sample filtered through a 0.4S micron pore size membrane filter [12, 13]. 

Process in which a precipitant is added incrementally to a highly dilute polymer solution and the intensity of light scattered by, or the turbidity due to, the finely dispersed particles of the polymer-rich phase is measured as a function of the amount of precipitant added. 

Iq is the intensity of light scattered at an angle 0 to the incident beam of the intensity /q /qS is the intensity of light scattered by pure eluent /is a constant for given instrument... 

An absolute value of M for each of these branched PVAcs was obtained from light-scattering measurements. In each case five polymer solutions were made up in tetrahydrofuran (THF) solvent and a Chromatix KMX-6 LALLSP instrument was employed to measure the intensity of light scattered from these solutions at 7° to the incident laser beam. A Chromatix KMX-16 laser differential refractometer was used to determine the refractive index increments, dn/dc, of the polymer solutions under ambient conditions. 

For polymers whose Mw < 10,000, the intensity of light scattering from the solution differs so little from the neat solvent that the determination is not precise. For polymers whose Mw > 10,000, the need to measure the light scattering at very small values of 0 is beyond the capability of many older instruments. Special treatment is required for mixed solvent systems, copolymers, higher polymers, and polyelectrolytes. 

Evaluate the intensity of light scattered at z Intensity of light is proportional to the square of the electrical field... 

Liquid solutions also scatter light by a similar mechanism. In the case of a solution, the scattering may be traced to two sources fluctuations in solvent density and fluctuations in solute concentration. The former are most easily handled empirically by subtracting a solvent blank correction from measurements of the intensity of light scattered from solutions. What we are concerned with in this section, then, is the remaining scattering, which is due to fluctuations in the solute concentration in the solution. 

If the intensity of light scattered by a colloidal dispersion is measured as a function of c and 0, the Zimm method enables us to convert this information into several parameters that characterize the colloid M, B, and Rg. In some situations this is more information than is actually needed. If spatial extension is the only information sought, a simpler method for evaluating it employs the so-called dissymmetry ratio. 

The authors attempted to measure the intensities of light scattered from a NIPA gel during the phase separation induced by a change in temperature [23]. In this study, we examined the applicability of Cahn s linearized theory [24] to the spinodal decomposition of the geL... 

Dynamical study of the phase transition of the gels in spinodal regimes was described. The evolution of intensity of light scattered from the gels indicated the applicability of Cahn s linearized theory to the phase transition. Our work offers a basis for the determination of diffusion coefficient of gels in their spinodal regimes. 

Compared to the colligative methods light scattering can yield information on a possible dissymmetry of the aggregates. For anisotropic particles the direction of the electric field associated with the incident light may not coincide with the shift of the electron cloud. The intensity of light scattered at (usually) 90° from anisotropic aggregates is increased over the value predicted on the basis of isotropy by the Cabannes factor. 

Field meters use the nephelometric method for turbidity measurements and read turbidity in Nephelometric Turbidity Units (NTUs). A nephelometer measures the intensity of light scattered by a sample and compares it to the intensity light scattered by a reference standard. Sample turbidity is proportional to the intensity of the scattered light. The reference standard is a formazin suspension in water, which has a known turbidity value. 

From Rayleigh theory, the intensity of light scattered from each droplet or particle depends largely on its size and shape, and on the difference in refractive index between the particle and the medium. For a dispersion, each spherical droplet, bubble, or particle scatters unpolarized light having an intensity l[Pg.24]

Data Transformation. The raw size distribution obtained in PCS is intensity weighted. Most particle sizing results are either mass, area, or number weighted. Therefore, to compare results, the PCS measurements would have to be transformed. If the ratio of the concentrations in each peak is desired, then a transformation is also necessary. The intensity of light scattered by a sphere is given by... 

When the sample contains particles of different sizes, the autocorrelation function will be a sum of decaying expontentials weighted by the intensity of light scattered from particles of each characteristic size. This can be described in general by the equation ... 

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