I am currently working with FT-IR (gas samples). I have a recurring problem in every spectrum. For some odd reason right side of my spectrum (i.e in the range 750-600 cm^-1) the spectrum shows complete transmission and it does not depend on the gas. Even the empty cell shows a similar result. I have attached a similar result for reference.
Thanks in advance.
Dear Maunabh Mandal,
If this behavior in the spectral range appears in all the samples, I think you could determine whether this is an original behavior for the sample or this comes from the measurement conditions.
Therefore, you could do the following things:
Firstly, you could record the background spectrum directly before recording every sample spectrum.
Secondly, you might know about the recommended spectral range in which the FTIR machine works properly.
Thirdly, you could record the spectrum of a standard sample to verify the FTIR machine's calibration.
Best Wishes
What you are seeing in this region is noise. There are a few reasons why this might be so...
The IR source is not producing much output at these wavelengths
The beamsplitter efficiency in this region is poor
The spectrometer optics are not allowing through these wavelenghts
There is also the problem that there are absorbances due to water vapour in this region which will have rotational fine structure producing lots of lines.
For the reasons outlined by David Stephenson - you should view the power/energy throughput of the system (no sample, no referencing) , which should be an option on the software.
What are your windows made of ? It looks as if you are getting total absorption of energy in this region.
Hugh J Byrne ,Geoffrey Dent , Abdu Saeed , David Stephenson Thank you for your helpful responses. The problem is solved. It was due to contaminated window cell and because I was not recording background scans. I realised these are rookie mistakes, sorry and thanks again !!
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