Please follow this method:
According to Beer's law:
Absorption, A = 2 - log10 %T ; Where %T is the percentange transmission
After converting the A into %T, now go for the alpha (absrption co-efficient).
Measure your sample thickness and put the thickness "d" in the formula below:
a (abs. coefficient) = { ln (100/(%T)} / d;
please go through below link for more clarification of The Beer-Lambert Law:
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Spectroscopy/Electronic_Spectroscopy/Electronic_Spectroscopy_Basics/The_Beer-Lambert_Law
Useful posts and resources
can be found below.
https://www.instanano.com/2017/01/Concentration-Calculation-UV-Vis-Absorbance.html
Article How to Measure and Predict the Molar Absorption Coefficient ...
Enjoy!
It is necessary to measure the absorbance (at a certain wavelength) of reagent solutions with different concentrations. Absorbance is plotted against the reagent concentration according Beer-Lambert Law. The slope of the linear regression is the molar absorption coefficient multiplied by the pathlength (oftenly 1 cm)
It is necessary to measure the optical density (A) of a solution of a precisely known concentration (c) several times at the maximum of the absorption spectrum at a cell length of l=1 cm, find the average value and calculate the molar absorption coefficient (epsilon) from the Lambert-Beer formula. In this case, you must be sure that the percentage of the substance in the compound used is close to 100 percent (or know the percentage of the substance, but then you need to multiply the molar coefficient by 100 and divide by the percentage of the substance.
https://www.chemguide.co.uk/analysis/uvvisible/analysis.html
this is very useful ...
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https://www.researchgate.net/post/How_to_calculate_absorption_coefficient_from_the_UV-Vis_absorption_data?_ec=topicPostOverviewFollowedQuestions&_sg=cJoNuHvQHXGAZjlJxD-n_p98ubvRXv1f1xEu2VIGmvU04ziA1ZgA6sbKnjAcbawSFQJEOXMcZ4y2MKVR
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Please look at the following below links which may help you in your analysis:
http://ioccg.org/wp-content/uploads/2015/10/absorption_protocol_forcommunitydistribution-sept2017-2.pdf
https://www.sciencedirect.com/topics/engineering/absorption-coefficient-alpha
https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2002.47.4.1261
Thanks
There are plethora of methods and one of them is as follows:
Draw the calibration curve from the calibration series (absorption diagram in terms of molar concentration of samples), then obtain the best possible line and finally, the slope of the line is equal to the absorption coefficient.
If you have determined it, never forget that your (molar) absorption coefficient is actually not a specific quantity. You have to determine it again if you change the solvent or the concentration range. Also, it is generally not a good idea to rely on Beer's law, meaning you do not always obtain a straight line, even in the absence of chemical interactions. For more information, see the following review: Article The Bouguer-Beer-Lambert Law: Shining Light on the Obscure
The UV-Vis. absorption titrations were carried out with a constant concentration of the test complexes (5.0×10-5 M) and various concentrations of receptor (0 to 2.5×10-5 M). The binding strength of the complexes with receptor can be estimated through the binding constant Kb (M-1), which is given by equation.
[ [R]/(ɛA-ɛf) ] = [ [R]/(ɛb-ɛf) ] + [ 1/Kb(ɛb-ɛf) ]
Where, [R] is the receptor concentration in base pairs, ɛA is the extinction coefficient was obtained by calculating the absorbance of the complex. The terms ɛf and ɛb are the extinction coefficients observed for the absorbance band at a given receptor concentration for free and bound complexes, respectively and Kb is the intrinsic binding constant determined from the slop to intercept ratio of a plot of [R] / ɛA-ɛf versus [R].
Bhavesh Socha Do you understand what you have written? Can anybody explain me?
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