How can calculate the optical absorption coefficient of colloidal QDs in a cuvette directly from absorbance or absorption spectra in order to calculate the optical bandgap?
I do not have the concentration of colloidal QDs. It is difficult for me to find it because the synthesized amount was small (about 0.2 mmol).
As shown in attached figures the samples have absorbance (optical density) = 0.046 (10%) at 325nm.
Please advise.
Do you mean absorption cross-section of single QDs or the cofficient that enters Beer-Lambert law? Why do you think you need this data (How do you want to use it)?
This link may be useful to you.
http://nopr.niscair.res.in/bitstream/123456789/25304/1/IJPAP%2040%284%29%20297-300.pdf
Cant you get the optical band-gap from the absorption 'onset' directly? The material begins to absorb photons only when photon energy is equal (or greater) than the band-gap. Since you are specifically trying to obtain 'optical band-gap', you don't have to worry about estimating the exciton binding energy.
Check this
http://www.perkinelmer.co.uk/Content/applicationnotes/app_uvvisnirmeasurebandgapenergyvalue.pdf
good luck !!
Dear sir:
I'm working theoretical field "Quantum Dot semiconductor laser" . you can ask :
Amin Al-Khursan
Hello. Firstly, I saw their spectrum, so you should remake, because the absorbance is above of the value of 0.1 ABS (A.U). This way, for more explanation you should read the paper in attachment and after you can use the my spreadsheet. Remenber this paper valid only for quantum dots CdTe, CdS, and CdSe.
http://pubs.acs.org/doi/abs/10.1021/cm034081k
Dear M. Jalalah, Beer-Lambert’s law is very useful to calculate the absorption coefficient.
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