Hi every scientific explorers?!
Recently, I'm trying to compare the optical properties of CsPbI3 perovskite quantum dot and p-PDI (N,N′-Bis(3-pentyl)perylene-3,4,9,10-bis(dicarboximide))
I think it is necessary to compare the absorption cross-section (σ) or molar extinction coefficient (ε) for the absorption of the two materials.
About PDI, molar extinction coefficient could be found in several papers.
The question I have right now is, Can I get molar extinction coefficient for cesium lead halide perovskite (CsPbX3) ?
If I can't, is there an equation that can covert the absorption cross-section of perovskite into molar extinction coefficient?
Also, is there an equation for converting the molar extinction coefficient of PDI to absorption cross-section?
Thank you :)
hello
you can estimate the life time of charge transfer and next can calculate the cross section
sincerally
copied from the site: https://www.aatbio.com/resources/faq-frequently-asked-questions/
What-is-a-molar-extinction-coefficient?
The term molar extinction coefficient (ε) is a measure of how strongly a chemical species or substance absorbs light at a particular wavelength. It is an intrinsic property of chemical species that is dependent upon their chemical composition and structure. The SI units of ε are m2/mol, but in practice they are usually taken as M-1cm-1. The molar extinction coefficient is frequently used in spectroscopy to measure the concentration of a chemical in solution.
You can use the Beer-Lambert Law to calculate a chemical species’ ε:
A = εLc
Where:
A is the amount of light absorbed by the sample for a particular wavelength. ε is the molar extinction coefficient. L is the distance that the light travels through the solution. c is the concentration of the absorbing species per unit volume
You can calculate the extinction coefficient from the measured absorption coefficient alpha as follows : alpha α = 4πk/λ , where k is the extinction coefficient. From the two relations one can get epsilon ε. The alpha is given in the the paper at the link:https://pubs.acs.org/doi/full/10.1021/acs.jpclett.8b01065?rel=12410&utm_source=Axial&utm_medium=Partner&utm_campaign=Newsletter0718
Best wishes
Abdelhalim abdelnaby Zekry
Thanks for your kind reply!!
But the question I have now is, what is the difference between extinction coefficient, k and molar extinction coefficient, ε.
Can extinction coefficient, k also be considered a intrinsic property of chemical species like molar extinction coefficient, ε?
Also, does the calculation, α = 4πk/λ apply to the Perovskite as well?
Thank you :)
Dear Jaesang Yu ,
Hope you are well!
In order to answer your question we have to refer to the definition of each one.
Let us recall
epsilon = A/Lc,
and k= A/L
Then it turns out that
epsilon= k/c
you need only to know the concentration of the absorbing species/cm^3
As a solid material what is commonly used parameter is k, the extinction coefficient. If the material is dissolved then one speaks from molar extinction.
It has no sense to consider epsilon for the solid absorbers. It is used for absorbing solutions.
This is my opinion that may need to be reviewed. Please review it and return to bus with final answer.
Best wishes
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