Quasi-elastic light correlation

Photon Correlation Spectroscopy. Photon correlation spectroscopy (pcs), also commonly referred to as quasi-elastic light scattering (qels) or dynamic light scattering (dls), is a technique in which the size of submicrometer particles dispersed in a Hquid medium is deduced from the random movement caused by Brownian diffusion motion. This technique has been used for a wide variety of materials (60—62). [Pg.133]

In dynamic or quasi-elastic light scattering, a time dependent correlation function (i (0) i (t)) = G2 (t) is measured, where i (0) is the scattering intensity at the beginning of the experiment, and i (t) that at a certain time later. Under the conditions of dilute solution (independent fluctuation of different small volume elements), the intensity correlation function can be expressed in terms of the electric field correlation function gi (t)... [Pg.12]

The technique is alternatively called photon correlation spectroscopy (PCS) or quasi-elastic light scattering (QELS). [Pg.62]

Dynamic (quasi-elastic) light scattering that is usually referred as photon correlation spectroscopy this is a rapid technique that is especially suited to measuring submicron particles (nanosize range). [Pg.152]

Two scattering methods, namely time-average (static) Hght scattering and dynamic (quasi-elastic) light scattering (also referred to as photon correlation spectroscopy PCS), will be discussed in the following sections. [Pg.311]

DLS is a method that measures the time-dependent fluctuation of scattered intensity, and is also referred to as quasi-elastic light scattering or photon correlation spectroscopy. The latter term is the most commonly used for describing the process, since most dynamic scattering techniques employ autocorrelation. [Pg.415]

We investigate here the dynamic behavior of fully charged NaPSS solutions with multivalent salt (LaCl3) measured by quasi-elastic light scattering. The bimodal decay of the correlation function of polyelectrolyte concentration (C) at constant salt concentration (Cs) is studied first. The ratio Cs/C varies from 0.2 to 10 2. Then the dynamics of the solution at constant C as a function of Cs from Cs/C approximately 10 2 to 0.2 are investigated. [Pg.136]

Polymeric materials were found in the toluene-insoluble fraction [127]. The materials have no solubility in common organic solvents or so-called fullerene solvents but are partially soluble in DMSO. Evidence for the polymeric nature of the materials includes results of dynamic scattering based on photon correlation spectroscopy of quasi-elastic light scattering (PCS-QELS) [128,129] and gel permeation chromatography using DMSO as mobile phase [117]. The structural characterization of the polymers remains a challenge. [Pg.370]

Dynamic light scallering (DLS). also known as photon correlation spectroscopy (I CS) and quasi-elastic light scattering (OFI.S). is a powerful technique for probing solution dynamics and fur measuring particle sues.-The DLS technique can obtain size information in a few minutes for particles with diameters ranging from a few nanometers to about 5 pm. [Pg.955]

This is also known as photon correlation spectroscopy (PCS) or quasi-elastic light scattering (QELS). It uses scattered light to measure the rate of diffusion of protein particles in a sample. The data on molecular motion are digitally processed to yield a size distribution of particles in the sample, where the size is given by the mean Stokes radius or hydrodynamic radius of the protein particles this is the effective radius of a particle in its hydrated state. Clearly, the hydrodynamic radius depends on both mass and shape. [Pg.139]

Unfortunately, because of space, we have not covered important new developments in light scattering for the study of nontransparent systems such as diffusion wave spectroscopy (DWS), fiber-optic quasi-elastic light scattering (FOQELS), dual-color cross-correlation, 3D crosscorrelation DLS, and improved techniques followed from these techniques [1-4]. [Pg.367]

Ford NC. Theory and practice of photon correlation spectroscopy. In Dahneke BE, editor. Measurement of Suspended Particles by Quasi-elastic Light Scattering. New York WUey-Interscience 1983. p 31. [Pg.388]

FRACTIONATION CREAMING WITH SODIUM ALGINATE OF A BUTADIENE-STYRENE LATEX AND PARTICLE SIZE CHARACTERIZATION BY QUASI-ELASTIC LIGHT SCATTERING USING PHOTON CORRELATION SPECTROMETER Macedo C M B Oliveira C M F Rio de Janeiro,Universidade Federal... [Pg.105]

The most commonly used technique for determining 5 is photon correlation spectroscopy (PCS) [also known as quasi-elastic light scattering (QELS)]. PCS has become one of the standard tools of the trade for the colloid chemist. In this technique concentration fluctuations arising from the diffusive motion of the dispersion particles give rise to fluctuations in the dielectric constant of the medium are monitored photometrically. These fluctuations decay exponentially with a time constant related to the diffusion coefficient, Ds, of the scatterer, which can in turn be related to its hydrodynamic radius through the Stokes-Einstein equation ... [Pg.82]

Photon correlation spectroscopy — also dynamic light scattering (DLS) or quasi-elastic light scattering (QELS) — is a robust and rapid method for size determinations in the colloidal range (from about 5nm to 1 m ). In PCS, intensity fluctuations of the scattered light due to particle motion are measured in dependence on time. By the diffusion coefficient of the particles in the measurement fluid, the particle diameter can be calculated according the Stokes-Einstein Eq. (9.1) under the assumption of a spherical particle shape ... [Pg.404]