- Static Light Scattering: This light scattering techniques is also
called Classical Light Scattering or Rayleigh Scattering. Static Light
Scattering is used for the determination of Molar Mass, Radius of
Gyration and the Second Virial coefficient (A2). In Static Light
Scattering, the absolute intensity of the scattered light is detected at
different scattering angles and the molar mass and radius is calculated
from this information. From the relation of molar mass and radius, the
so-called conformation plot, additional information about the shape and
structure can be extracted. Once this light scattering technique is
set-up properly, absolute measurements of molar mass and particles size
can be performed without the use of standards.
- Dynamic Light Scattering: This light scattering technique is also called Photon Correlation Spectroscopy (PCS) or Quasi Elastic Light Scattering (QELS). The fluctuation of the scattered light at a certain angle as the effect of the Brownian Motion of the molecules and particles is detected in Dynamic Light Scattering. A correlation function is established using this light scattering data and from that the Hydrodynamic Radius can be calculated from the Dynamic Light Scattering data.
The scientific attractiveness of light scattering is based on the unique combination of high sensitivity, high resolution, easy handling and fast analysis times. Other techniques, which can be seen more as complementary than competing, are Analytical Ultracentrifugation, Mass Spectroscopy and membrane Osmometry. Analytical Ultracentrifugation for example shows high resolution, but is much more expensive and complicated and has longer run times. Mass Spectroscopy has become very famous in the last decade, but this technique also requires a big investment and does not reach the same upper molar mass range as light scattering does. Membrane Osmometry is another suitable technique, but it is not possible to use this technology as online detector and the resolution and molar mass range is much more restricted than what can be expected from light scattering.