is dynamic light scattering and static light scattering are both same or completely different?how dynamic light scattering works and where it is useful and how static light scattering works and where it is useful.can anyone give proper justification for both?
Hello Shanker,
Dynamic light scattering (DLS) and Static light scattering (SLS) can be complimentary and can sometimes be done within a single commercial instrument, however the principals behind them are significantly different.
Static light scattering involves recording the amount of light scattered by a sample, either at a range of angles and/or for different sample concentrations.
Recording the intensity of light scattered at different angles allows theoretical models to be used to determine the size, shape or structure of the scattering material.
Some SLS measurements use the intensity of light scattered at different concentrations of the sample in order to determine sample properties like molecular weight and second virial coefficient.
DLS uses the recording of the fluctuations in scattering intensity over time in order to characterise motion within the sample. By quantifying these fluctuations, through either correlation or spectral analysis, diffusion coefficients can be calculated which in turn can be used to determine hydrodynamic radius.
In short, DLS measures how scattering changes over time, regardless of the amplitude (amplitude only matters for instrumentation optimisation), and SLS measures the amplitude of scattering, regardless of its fluctuations.
The following link offers a more detailed description of DLS and maybe of interest, but I'll happily try to answer any other questions that you may have.
http://www.malvern.com/en/support/resource-center/technical-notes/TN101104DynamicLightScatteringIntroduction.aspx
Dear Malm,
Thanks for your valuable answer.
Can you please suggest the globule size method development of an emulsion. Which parameters will effects more and how it will? which parameters need to incorporate in method development.
@ Shanker Many emulsions will be measured by laser diffraction and not DLS so some more details of your system re necessary in order to understand if DLS is applicable. If you have a milky emulsion it's almost certainly a diffraction application. If you have a 'microemulsion' that's clear/transparent then it's DLS.
@ Shanker. Nothing important to add to former answers really . Maybe just a useful picture to understand DLS: A moving object reflecting monochromatic light experiences Doppler effect. For suspended particles, small shifts in frequency are produced and can be easily related to the movement. If this movement is correctly related to the size, shape and viscosity of the medium, then you start to obtain information.
While SLS is all about scattering models, DLS is more about combining scattering and hidrodynamic models.
From the intensity fluctuations in time, information on the dynamics within the solution are obtained. The evaluation of the fluctuations is commonly named as dynamic light scattering (DLS) while the analysis of the absolute mean intensity is known as static light scattering (SLS). The intensity is very sensitive to variations in size of the solutes, so that it is advantageous to investiagte aggregation in solution. SEE THIS WEB SITE
http://www.soft-matter.uni-tuebingen.de/index.html?dls.html
@Alan F Rawle what do you recommend for 30 - 150 nm emulsion?
Is Malvern Mastersizer 3000 suitable? I ve got good reproducibility, it is SLS. Or it is better to try ZetaSizer?
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