The circular shape porous membrane is of 70 micron thick is made up of GNP's and ZnO nanocomposite using vacuum filtration technique onto AAO Al membrane as shown in the attached picture. I wish to investigate the UV-VIS optical properties of the nanocomposite.
If you want to collect an absorbance spectrum, diffuse reflectance is the best option, since your film looks to have low specular reflection (does not appear to have a mirror finish). If you want to learn more about the material's properties I would suggest variable angle spectroscopic ellipsometry. If you do not have access to the instrument, some instrument companies will run demonstration samples for you to show the utility of the measurement.
Whan kind of properties are you interested in? You can try to measure reflection spectrum as well as emission for such a sample.
Reflection is the best way using integrating sphere. Also, you can reconstruct the absorption spectra from the excitation measurements if your sample is not sensitive to the light
If you want to collect an absorbance spectrum, diffuse reflectance is the best option, since your film looks to have low specular reflection (does not appear to have a mirror finish). If you want to learn more about the material's properties I would suggest variable angle spectroscopic ellipsometry. If you do not have access to the instrument, some instrument companies will run demonstration samples for you to show the utility of the measurement.
First you need is an integration sphere capable uv-vis or fluorescence spectrophotometer. Later on you can develop analogy analysis of resulting spectra, e.g. compare the spectra of the film against unmixed samples. Also try angular reflection spectra, which depending on the angle of incidence should provide above or below layer transitions. Hope this helps.
Julian Menter, Morehouse
School of Medicine. I agree, you need an integrating sphere to catch all scatterd and refelcted light
Using a transparent membrane for collecting the nanoparticles, it could be possible to measure absorbance simply in transmitting mode, which is much easier with a standard UV/VIS spectrometer at hand.
Apart from this, the UV/VIS spectra will be quite boring, as the substance is apparently of grey color, which means there is roughly the same absorbance value at each (visible) wavelength...
Dear All,
I thank you very much for your kind suggestions.
I have tried an experiment on this hybrid membrane for UV-VIS absorption spectra (using Cary-5000). But, I have noticed that the light of all wavelength has been absorbed which is unexpected. I understand that this could be due to the light trapped inside the pores of the membranes.
Just to make it clear: a grey coloured substance has measurable absorption at all wavelengths in the visible range. However, your filter has to be nearly transparent, otherwise you will measure the filter's absorption properties...
I would suggest removing the NPsfrom the filter into a solution. You can try to wash the NPs from the filter with whatever solvent you used for the vacuum filtration. In that way you can achieve relatively high concentration of the nanocomposite in solution. This way you would be able to measure the transmission/absorbance of the nanocomposite in solution.
Why do you need it on the membrane?
Dear Chandra,
Please try with diffuse reflectance mode at different angle of incident light on your substrate. Measure UV-VIs absorption as a function of wavelength..
I think this will helpful to you .
Dear Nikodem Czechowski,
Let me explain why I am using membrane and my goal.
The main idea is to tune the electrical and optical properties of the GNPs with ZnO nanostructures. For this, I need to understand their DC conductivity (and also charge) and UV-VIS absorbency measurements.
However, I will consider the suggestion of many to use Diffuse Reflectance Mode to resolve the issue.
Dear Chandra, I fully understand it now. But do you need to perform both measurements - DC and UV-VIS - at the same sample, prepared in the same manner? If so, I strongly suggest measuring reflectivity or scattering.
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