Towards band gap energy, Diffuse reflectance spectra shows different band gap identity. But I need to know about measuring mode parameters (absorption, energy and transmittance option) in UV-Visble spectrometer. Please tell more about energy options.
I assume from the terms that you are using within your text that you are interested in using UV-VIS spectroscopy for measuring the band gaps in solid state samples. Depending upon the material and its optical properties, this can either be relatively easy or quite difficult. Most of the "off the shelf" UV-Vis instruments sold are designed to measure liquids in sample glass cuvettes.
With solid samples, of varying real and imaginary refractive indices it may be difficult resolving the amount of the sample beam that is reflected as compared to the amount that is absorbed.
If you have a UV-Vis spectrometer that has an integrating sphere sampling device, that issue is significantly reduced. These are not extremely common, but are available.
The wavelength or energy resolution is variable from tens of nanometers to small fractions of a nanometer depending upon the UV/Vis spectrometer.
If you are setting up a spectrometer to measure this regularly for a long period of time, it may be worth getting a semi-custom spectrometer built. If this is a one time measurement, find someone who does this regulalrly and have them measure it for you.
If you go with the semi-custom instrument option, let the spectrometer designers design the spectrometer to your specifications, working ou with them what you really need. You will same a lot of time and money letting the experts design the system.
The UV-Vis spectrum represents intensity as a function of the energy. Intensity can be presented as absorbance or transmittance. The transmittance is a ration between intensity of the light after and before the sample. The absorbance can be calculated from the transmittance. With the energy scale is a little bit different - the spectrophotometers now use grating as monochromator, so this scale is presented as wavelengths, the walenumbers (energy) can be rescalculated (in cm^-1 just staking 10^7/lambda in nm). I recommend you the book of Perkampus for UV-Vis spectrometry.
Dear Prof.,
Thanks, i got your good message.
We are having Shamadzu 2450 UV visble spectrmeter. when i try to solid sample Diffused reflectance spectra for Band gap calculation. I thought why not with energy / transmittance measuring mode option. Is there any calculation for Band gap using Energy / Transmittance option
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