We are doing optical emission spectroscopy of different atmospheric pressure non-thermal plasma for identification of different species. We have witnessed that when we are taking spectrum of a 2.45 GHz microwave plasma, we are getting a clear spectrum. However, whenever we try to take spectrum of 13.56 MHz RF plasma, the spectrum gives huge noise especially between 200 - 500 nm. We don't know why ? I am attaching two spectral images for your consideration. You can clearly see the differences there. Kindly help.
Dear Rajib,
Hope you are well,
The observed spectrum reflects the optical activity resulting from the gas discharging process. It is apparent that there are electrons which will return from an excited electronic sate that is a shallow electron levels with a band of allowed electronic levels to electronic levels in the atoms or molecules. My expression means there is fall of electrons from an allowed range of energies to a discrete electron level inside the atoms.
Best wishes
Dear Rajib,
What is presented in Hindawi link is experimental results of different gas plasma.
They did not account on the formation of a continuous spectrum at the shorter wavelength range. My explanation conforms well with the observed experimental results.i noticed that you passed on my answer without comment and it is based on the allowed energies in the atoms and molecules.
Best wishes
This range also lies in Visible part of the spectrum. Better way while recording the spectrum turn off the visible lights and remove the background radiations from the recorded spectrum.
Please check specifications of your spectrometer. If the CCD responce is corrected to obtain absolute values of input aperture irradiation (absolute calibration procedure done), signal for shorter wavelength may be overamplified due to lower sensitivity of CCD in that spectral region. You will simply get amplified thermal noise of your CCD if sensitivity is lower than required. Use specially configured spectrometer for UV region (with special CCD, produced by Hamamatsu https://www.hamamatsu.com/eu/en/product/type/S10420-1104-01/index.html, for instance) to get more adequate spectra.
It is better to turn off light and your mobile phone..
Dear Dr. Reza Fotohi , can anyone really find NO bands in Ar+O2 mixture?
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