To use all functions of this page, please activate cookies in your browser.
With an accout for my.chemeurope.com you can always see everything at a glance – and you can configure your own website and individual newsletter.
- My watch list
- My saved searches
- My saved topics
- My newsletter
Static light scattering
Static light scattering is a technique in physical chemistry that uses the intensity traces at a number of angles to derive information about the radius of gyration , molecular mass of the polymer or polymer complexes, and the second virial coefficient , for example, micellar formation (1-5).
There are typically a number of analyses developed to analyze the scattering of particles in solution to derive the above named physical characteristics of particles. A simple static light scattering experiment entails the average intensity of the sample that is corrected for the scattering of the solvent will yield the Rayleigh ratio, as a function of the angle or the wave vector as follows:
One must note that although data analysis can be performed without a so-called material constant defined below, the inclusion of this constant can lead to the calculation of other physical parameters of the system.
where is the refractive index increment, is the refractive index of the solvent, is Avogadro's number (6.023x1023) and is the wavelength of the laser light reaching the detector. This equation is for linearly polarized light like the one from a He-Ne gas laser.
Additional recommended knowledge
The scattered intensity can be plotted as a function of the angle to give information on the which can simple be calculated using the Guinier approximation as follows:
The Kratky plot is typically used to analyze the conformation of proteins, but can be used to analyze the random walk model of polymers. A Kratky plot can be made by plotting versus or versus .
This method is used to derive the molecular mass and 2nd virial coefficient,, of the polymer or polymer complex system. The difference to the Zimm plot is that the experiments are performed using a single angle. Since only one angle is used (typically 90o), the cannot be determined as can be seen from the following equation:
For polymers and polymer complexes which are of a monodisperse nature as determined by dynamic light scattering, a Zimm plot is a conventional means of deriving the parameters such as , molecular mass and the second virial coefficient .
One must note that if the material constant defined above is not implemented, a Zimm plot will only yield . Hence implementing will yield the following equation:
1. A. Einstein, Ann. Phys. 33 (1910), 1275
2. C.V. Raman, Indian J. Phys. 2 (1927), 1
3. P.Debye, J. Appl. Phys. 15 (1944), 338
4. B.H. Zimm, J. Chem. Phys 13 (1945), 141
5. B.H. Zimm, J. Chem. Phys 16 (1948), 1093
Categories: Polymer chemistry | Polymer physics | Physical chemistry
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Static_light_scattering". A list of authors is available in Wikipedia.|