In DLS there were 2 peaks major one centred at 113.9 nm and the other one was at 21.39nm.In DLS we are getting hydrodynamic size and in TEM the size will be real,right?
Please post an example DLS distribution and TEM photograph. Also indicate what liquid the particles were dispersed in.
Harsha Haridas e S One question for you to answer. What is the diameter of a hydrogen atom? Why is it relevant to your question?
DLS provides an intensity distribution proportion to r6 (or volume2) whereas TEM provides a number distribution (proportional to r0 - numbers of particles). TEM will examine the metallic core of the particle ignoring the essential protective and stabilizing layers (can't be seen) whereas DLS will consider the movement and interactions of the entire particle (core + protective layers). They are different but both are correct if the experiment has been conducted correctly. Understand the reasons for the differences and quote a reasonable number of decimal places.
Please explain your TEM sample preparation as artefacts are likely especially if microtoming is involved. Why?
You have also to understand the effect of aggregation and agglomeration on any measurement and subsequent calculations and posting a TEM image will be very useful as @John Francis Miller states. Do you buy breakfast cereal on the basis of the numbers of particles/corn flakes in the box?
Hello Harsha, just a few questions :
- What fitting algorithm do you use to treat your raw correlograms? Cumulants? NNLS?
- Are you looking at your distributions in intensity? number? volume?
If you are looking at them in intensity, I would say that parts of your sample may aggregate spontaneously. Then, those bigger objects are going to scatter more than the smallest ones (which you are interested in). This leads to a big peak for the bigger objects, even if they are only representing a small part of your sample. By sonication, vortex or an other "de-aggregation technique", you should be able to get rid of that bigger peak.
Keep us updated :).
If your DLS system happens to be a classic Zetasizer Nano, you can find the data file (".dts") on your computer. Details are in https://www.materials-talks.com/faq-how-can-i-submit-a-data-file-to-the-help-desk/
In addition, the size is different for different techniques and there is a mean size and a size distribution. You may also find the below blog posts of interest:
https://www.materials-talks.com/intensity-volume-number-which-size-is-correct/
https://www.materials-talks.com/faq-peak-size-or-z-average-size-which-one-to-pick-in-dls/
https://www.materials-talks.com/peak-number-order-in-dls-which-is-peak-one/
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