Surface quasi-elastic light scattering

It is very well known that the nature of the monolayer partially depends on the strength of interfacial interactions with substrate molecules and that of polymer in-tersegmental interactions. And it is normal to expect that the viscoelastic properties of polymer monolayer are also dependent on these factors. The static and dynamic properties of several different polymer monolayers at the air - water interface have been examined with the surface quasi-elastic Light Scattering technique combined with the static Wilhelmy plate method [101]. 

SURFACE QUASI-ELASTIC LIGHT SCATTERING (SQELS)... 

Figure 12.17 Schematic diagram of surface quasi-elastic light scattering apparatus. LI, L2 lenses, T = transmission grating, F — neutral density filter. Ml, M2, M3, M4 mirrors...

A diffuse layer is observed at the surface of a crystal which is growing into the melt. The building up of this layer and the dynamics of entropy fluctuations have been studied by quasi elastic light scattering. Water and salol have been used as test substances. In a stationary non equilibrium steady state the layer is several thousand lattice constants thick. The diffusion constant, which determines the dynamics of the entropy fluctuations in this layer, is Dj 3 10 cm /s. It is isotropic in space. During freezing fluctuations in order can not be separated from fluctuation of heat. Therefore we interpret D as J. Frenkel s constant of "structure diffusion". 

K. Ito and R. Hayakawa. Quasi-elastic light scattering with the sinusoidal electric field New measurement methods and frequency dispersion of the electrophoretic mobility and diffusion constant of polyions. Colloids and Surfaces A, 148 (1999), 135-148. 

The adsorption of DNA films assembled from oligonucleotides composed of two homopolymeric diblocks (polyA G and polyTnCn) were studied in the presence of salt. The growth of fihn increased with salt concentration [22]. The studies on polyelectrolyte complexation have offered wide applications such as water treatment, surface modification, dmg delivery system, tissue engineering. To understand the formation of protein-polyelectrolyte complex is important due to the interaction between polyanions or polycations with protein macromolecules or polyelectrolytes. Soluble complexes can be formed and amphorous can be precipitated with the interaction of molecules. Complex formation is generally performed in the bulk solutions. Potentiometry, conductometry, viscosimetry, turbidimetry, or electrophoretic and quasi-elastic light scattering are used to follow... 

Fig. 18.1 A dressed-state model that is used in the text to describe absorption, emission, and elastic (Rayleigh) and inelastic (Raman) light scattering. g) and. v> represent particular vibronic levels associated with the lower (1) and upper (2) electronic states, respectively. These are levels associated with the nuclear potential surfaces of electronic states 1 and 2 (schematically represented hy the parabolas). Rj are radiative continua— 1 -photon-dressed vibronic levels of the lower electronic states. The quasi-continuum L represents a nonradiative channel—the high-energy regime of the vibronic manifold of electronic state 1. Note that the molecular dipole operator /t couples ground (g) and excited (s) molecular states, but the ensuing process occurs between quasi-degenerate dressed states g,k and 5,0).

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