I working with Carbon nanodots(c-dots) I would like to measure the Quantum yield for prepared samples and also I am very eager to measure the Two Photon Absorption(TPA). In order to realize the above both measurements i need to know the concentration of C-dots in solutions as well as my C-dots are water soluble. How could I do this? I want the details of this. Thanking you in advance all researchers.
Concentration is not necessary for quantum yield determine. If you can get the Integrating Spher for absolute QY analysis. you can direct measure it. If not, you can use a reference dye to calculate relative quantum yield.
If you still needs the concentration, here is my approach.
1.First you needs to purify your sample by dialysis to remove salt, precusor, and byproduct.
2. Analysis the sample with TEM to determine the size of C-dot. and calculate the volume of single particle.
3.Dry a 100 mL C-dot solution to get the powder of C-dot and weight it before and after drying. (determine the density and the weight of C-dot in 100 mL solution)
4. calculate the density of C-dot using information from step 3.
5. dry weight of c-dot / density of c-dot = total volume of c-dot.
6. total volume/ single particle volume =number of particle, then you can get the concentration.
Concentration is not necessary for quantum yield determine. If you can get the Integrating Spher for absolute QY analysis. you can direct measure it. If not, you can use a reference dye to calculate relative quantum yield.
If you still needs the concentration, here is my approach.
1.First you needs to purify your sample by dialysis to remove salt, precusor, and byproduct.
2. Analysis the sample with TEM to determine the size of C-dot. and calculate the volume of single particle.
3.Dry a 100 mL C-dot solution to get the powder of C-dot and weight it before and after drying. (determine the density and the weight of C-dot in 100 mL solution)
4. calculate the density of C-dot using information from step 3.
5. dry weight of c-dot / density of c-dot = total volume of c-dot.
6. total volume/ single particle volume =number of particle, then you can get the concentration.
Thank you very much Tzu-Heng Chen. how could i calculate volume of single particle frommy TEM images. Already I found the size of the C-dots about ~3.5 nm.
Under assumption of the shape of C-dot is perfect sphere, the volume would be
4/3 pi r^3 where r is 3.5 / 2 = 1.75
Dear Jay
Its interesting...
I am agree with Chen answer for QY calculation.
When concentrations of fluorophore are exactly not known e.g. Carbon dots, Semiconductor QDs etc. In such cases we can proceed for comparison method reported by J. R. Lakowicz. I think it is more appropriate and suitable method.
Our group also following the same method for QY calculation.
http://link.springer.com/article/10.1007/s10895-015-1594-1
Prepare 4 ~ 5 samples of unknown having different absorbances between 0.01-0.1 at the excitation wavelength. Follow same procedure for reference.
More detail see attached file herewith ...
Thank you T.H.Chen and Anil., for your kind suggestions about my queries. I will go through the articles which attached here.
Dear Tzu-Heng Chen,
Thank you so much for this valuable information. Could you please tell me what would be the final unit of this calculation. It means, after calculation what should I write as a unit? Whether I should mention mg/mL or other?
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