I have been using DLS to characterize my Pt nanoparticles as well as AFM and TEM, my AFM and TEM results match up but the intensity distribution doesn't that's why I'm using the number distribution but I would like to know how does the software do the conversion.
Thanks
The intensity size distribution is determined directly from the analysis of the correlation functions recorded by the DLS instrument through an NNLS analysis.
A caviate to using this data, is that scattering intensity for light is a function of particle size (~r^6), meaning that larger particles scatter more dominantly than smaller ones.
The intensity size distribution can be converted to number distribution by rescaling the data based on light scattering theory, assuming that the refractive index of the scattering sample is known.
Further information regarding the different size distributions can be found here:
http://www.materials-talks.com/blog/2014/01/23/intensity-volume-number-which-size-is-correct/
Keep in mind that from this diffusion coefficient (result of the dynamic light scatering) the hydrodynamic diameter can be calculated.
The hydrodynamic diameter can be larger than the diameter optaiend by TEM.
Hi,
Thank you for your responses.
Yes I know that DLS will give me a hydrodynamic diameter, however I watch a webinar of the same company (Malvern) explaining how to understand the different distributions (Volume, Number and intensity).
Unfortunately, they explain and they don't go through the calculations on how they do that, the software itself has an algorithm that does the conversion automatically. That's what I want to know, what is the fundamental of the conversion.
Thanks
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