I am working with cuins2 thin films. In the absorption spectra initially Absorbance decreases with wavelength and after 700 nm it increases. PLEASE give me the reason.
This could due to the combination of baseline correction and autozero/ setzero. It is always help if you show the spectra.
Dear Sumita Sengupta,
if you can determine the absorption edge, to see if there is a mistake or not.
The absorbance is quite high. Ideally the absorbance should not exceed 1. Decrease the concentration to see whether the spectrum changes. How different is your spectra from literature report?
The relationship between absorbance and wavelength is direct, you can re-check the absorption spectrum to check the behavior of the material, or perhaps the materials in the films are heterogeneous.
Would you please redraw the graph as Transmittance versus wavelength and upload. You would be able to see clearly where the fundamental absorption edge is falling and then we can account for the rest of the absorption at higher wavelengths. Hope you know the relation between absorptance and transmittance.
Dear Sumita Sengupta
From the spectrum, it looks that what is formed is not CIS but a secondary phase lie those of copper sulphide. Please check.
The absorbance nature at higher wavelengths could be because of free carrier absorption. But the transmittance spectrum you have uploaded does not show that trend since at higher wavelengths , transmittance is almost same. Pl check your absorbance calculations at higher wavelengths.
The onset of transmittance fall occurs at ~ 600 nm and it no way matches that of CIS. The 2 theta values of the most intense peaks of CIS and CuXS might be close. Pl check. You have several phases of copper sulphide like Chalcocite, Deginite, Djurlite, covilte etc.
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