Experiments light scattering

This expression applies to small scattering angles and low concentrations. 

4 Light-Scattering Experiments From Eqs. (2.104) and (2.113), we finally obtain 

The Rayleigh ratio eliminates the geometry-dependent factors in I (k)/Io such as the scattering volume V(9) and the detector-sample distance r and retains the factors related to the solution only. In the actual measmement system, /q and V d) cannot be measured correctly. Therefore, a pure solvent such as benzene and toluene is used as a calibration standard. See Refs. 21 and 22 for details. With Rg, Eq. 2.114 is rewritten to 

The equations we derived in the above assume that the polymer in solution is monodisperse. Usually, the polymer is polydisperse. M and that we obtain in the static light-scattering experiments are then averages of M and R. Below we find what kind of averages they are. 

For a monodisperse polymer, I /Io cM- l/3)k cMR in the low concentration limit. When the solution contains components of molecular weight M, and radius of gyration R i at concentration c, (c = 2c,), the total excess scattering intensity from all the components is 

---

In the next section we discuss linear hydrodynamics and its role in understanding the inelastic light scattering experiments from liquids, by calculating the density-density correlation fiinction,. Spp. 

Out of the five hydrodynamic modes, the polarized inelastic light scattering experiment can probe only the tliree modes represented by equation (A3.3.18), equation (A3.3.19) and equation (A3.3.20). The other two modes, which are in equation (A3.3.17), decouple from the density fluctuations diese are due to transverse... 

Figure A3.3.3 Time-dependent structure factor as measured tlnough light scattering experiments from a phase...

This is the basic equation for monodisperse particles in light scattering experiments. We can derive tln-ee relationships by extrapolation. 

Vimses are also detectable with imprinted sensor materials thus leading to the first tme rapid on-line analysis for these species that are too small for e.g. light scattering experiments. So we e.g. succeeded in determining the tobacco mosaic vims (TMV) in plant saps as well as the Human Rhinovims (HRV). 

Dynamic light-scattering experiments or the analysis of some physicochemical properties have shown that finite amounts of formamide, A-methylformamide, AA-dimethyl-formamide, ethylene glycol, glycerol, acetonitrile, methanol, and 1,2 propanediol can be entrapped within the micellar core of AOT-reversed micelles [33-36], The encapsulation of formamide and A-methylformamide nanoclusters in AOT-reversed micelles involves a significant breakage of the H-bond network characterizing their structure in the pure state. Moreover, from solvation dynamics measurements it was deduced that the intramicellar formamide is nearly completely immobilized [34,35],... 

In our earlier efforts to synthesize dendritic amphiphiles, we described a triden-dron (43) which was prepared by a two-step (alkylation-amidation or triester-tris) reaction sequence applied to l,3,5-tris(bromomethyl)benzene [117]. TEM and light scattering experiments suggested that 43 aggregated by stacking of its hydrophilic exterior into a spherical array of ca. 20 nm (diameter) reminiscent of globular micelles. 

Raman spectroscopy is an inelastic light scattering experiment for which the intensity depends on the amplitude of the polarizability variation associated with the molecular vibration under consideration. The polarizability variation is represented by a second-rank tensor, oiXyZ, the Raman tensor. Information about orientation arises because the intensity of the scattered light depends on the orientation of the Raman tensor with respect to the polarization directions of the electric fields of the incident and scattered light. Like IR spectroscopy, Raman... 

Additional insights into the dynamics and structure of bimodal elastomers have been obtained by dynamic light-scattering experiments [129], neutron scattering experiments [130] and calculations [131], dual cross-linking system experiments [132], non-affine swelling [133], and the computer simulations already mentioned. 

In addition, data on the size, shape and solvation of the polymer particles in aqueous solutions at temperatures below and above the transition phenomena registered by HS-DSC have been obtained [42]. Table 2 shows the results of capillary viscometry and light scattering experiments for the fractions p and s of poly(NVCl-co-NVIAz) synthesized at 65 °C from the feed with the initial molar comonomer ratio equal to 85 15. Since fraction p precipitates from the aqueous solution at temperatures > 34 °C, its intrinsic viscosity can be determined only at 20 °C, whereas for the fraction s such measurements were possible above and below the temperatures of the HS-DSC-registered conformational transition. 

The incorporation of non-Gaussian effects in the Rouse theory can only be accomplished in an approximate way. For instance, the optimized Rouse-Zimm local dynamics approach has been applied by Guenza et al. [55] for linear and star chains. They were able to obtain correlation times and results related to dynamic light scattering experiments as the dynamic structure factor and its first cumulant [88]. A similar approach has also been applied by Ganazzoli et al. [87] for viscosity calculations. They obtained the generalized ZK results for ratio g already discussed. 

Antibiotic Mg complex induced alteration in the ultrastructural changes in the native and HI depleted chromatin were monitored by thermal melting analysis, polyacrylamide gel mobility assay, dynamic light scattering experiments and transmission electron microscopic studies. Micrococcal nuclease digestion is the biochemical probe to assess the accessibility of the antibiotic Mg + complexes to nucleosomal DNA. 

We have identified three diffusion coefficients. These are the self-translational diffusion coefficient D, cooperative diffusion coefficient Dc, and the coupled diffussion coefficient fly. fl is the cooperative diffusion coefficient in the absence of any electrostatic coupling between polyelectrolyte and other ions in the system, fly is the cooperative diffusion coefficient accounting for the coupling between various ions. For neutral polymers, fly and Dc are identical. Furthermore, we identify fly as the fast diffusion coefficient as measured in dynamic light scattering experiments. The fourth diffusion coefficient is the slow diffusion coefficient fl discussed in the Introduction. A satisfactory theory of flj is not yet available. 

Therefore we expect Df, identified as the fast diffusion coefficient measured in dynamic light-scattering experiments, in infinitely dilute polyelectrolyte solutions to be very high at low salt concentrations and to decrease to self-diffusion coefficient D KRg 1) as the salt concentration is increased. The above result for KRg 1 limit is analogous to the Nernst-Hartley equation reported in Ref. 33. The theory described here accounts for stmctural correlations inside poly electrolyte chains. 

---