I have taken transmission percentage spectroscopy data as a function of incident wavelength. (This is often used for finding a materials bandgap). However, the transmission data gradually increases with increasing wavelength. One side of the material is very well polished and the other is not polished but finely ground. My thought is that the transmission data is affected from the rough surface and light scattering. Is this a potential cause of the data acting like this? If so how can this be more aptly explained?
Dear Dr.Jacob
Many information is missing in your question, for example what is the material you are talking about and its thickness. Further, by increase in transmission data do you mean increase in transmission percentage? From the question i understand that transmission is increasing with increasing wavelength, depending on the material that may not be unusual as the absorption can be associated with imaginary part of the refractive index (RI) and it varies with incident frequency. IF you can afford to polish the other surface too, you can do it and check the transmission to assess the role of scattering to qualitatively explain the contribution due to scattering.
The wavelength dependence of scattering is certainly a plausible explanation. See for example this tech note on diffusers. There is a graph of transmission vs wavelength if you scroll down a bit.
https://www.edmundoptics.com/knowledge-center/application-notes/optics/understanding-white-diffusing-glass/
Yes, this is typical of Mie-like scattering, which, for a fixed particle/feature size, is inversely proportional to wavelength.
https://en.wikipedia.org/wiki/Mie_scattering
Jacob Blevins , your data definitely will be affected by scattering and by its wavelengths' dependence. You can find description of such processes in book:
Stover, J. C. Optical Scattering: Measurement and Analysis
Hugh J Byrne , I'm not sure that Mie scattering, which describes scattering of single sphere could be applied for description of such processes.