How can I calculate the absorption coefficient from an absorbance vs wavelength graph for a glass from the UV-Vis Absorption Spectroscopy???
the absorption coefficient is a function of wavelength. for any given wavelength in your spectrum you can convert the measured absorbance using the Beer-Lambert relation
Yes, you can calculate the absorption coefficient from the absorbance data as suggested by Dr.Kiefer. However, you have to ensure that reflection data has been taken into account. Even on glassy transparent material is about 5% which is not negligible. Sometimes, instrument measures transmission and calculate absorption percentage as 100 - transmission %.
Please see
https://www.researchgate.net/post/Without_recording_Absorbance_spectra_A_can_we_use_Beers_law_to_calculate_A_from_Transmittance_spectra_T?_tpcectx=qa_overview_following&_trid=5533e582d4c118ea058b4567_
This is deduced from the Beer-Lambert law, see e.g. chapter 7.6.3 (and 3, 4 and 7.6.7 for additional information) in the following article: B. P. Jelle, ”Solar Radiation Glazing Factors for Window Panes, Glass Structures and Electrochromic Windows in Buildings - Measurement and Calculation”, Solar Energy Materials and Solar Cells, 116, 291-323, 2013. Furthermore: T + A + R = 1 (100 %) where T = transmittance, A = absorbance and R = reflectance between 0 to 1 (or between 0 to 100 %). Note that the absorbance A in the above is not the absorbance A’ on the logarithmic form, i.e. not the optical density OD, which is a common output from many spectrophotometers (OD = A’ = log10(1/T), "10" supposed to be as a subscript here, i.e. the 10-log). In general, a spectrophotometer working in the solar radiation wavelength region measures either the transmittance or the reflectance of a sample. That is, the absorbance is not measured directly, but is calculated from the measured transmittance and reflectance (if both can be measured). When a spectrophotometer gives you the absorbance A’ on the logarithmic form, i.e. the optical density OD, which is a common output from many spectrophotometers, it is in reality a calculation from the measured transmittance ignoring the reflectance. A spectrophotometer measures the radiation which is collected by the detector from either the transmitted or the reflected beam.
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