Hi,
I have been analysing gas phase organic solvents with the help of FTIR. The spectrum looks a bit weird around 1200 cm^-1 (see attached image). I noticed a similar behaviour when the gas cell (used to store the gas phase organic solvent) is empty. I have also analysed both windows separately, they produce almost identical spectrum.I concluded that the window of the gas cell is causing this absorbance.
Attached below you will find the spectrum of Acetone and empty glass cell with either of the windows.
Has anyone faced this problem? Can anyone please help me or explain why this is happening?
Thanks in advance
Maunabh Mandal
What is the material of the windows?
It I would guess that it is CaF2 with and adsortption limit of 900 wavenumbers.
Both windows you mean you have two pairs of windows?
1 pair CaF2 and 1 pair KBr?
If you mean this and i look to you specatra i would guess, sombody has mixed the windows.
Measure each window in transmission and not in the gas cell.
For gas phase analysis you normal use a pair of windows out of the same material. If you used a mixture of KBr/CaF2, CaF2 is the limiting Faktor your measurment, this would fit to the observed spectra.
Thomas Mayer-Gall
Thank you for the answer. If thats the case why both the windows have similar spectra ?
The IR analysis of the windows were performed individually.
if the spectras are the same, then the material is the same. The spectra is not KBr for sure. Both windows are CaF2!
Normally for a gas-transmission measurment you would use twice the same material.
compare CaF2:
https://www.spectral-systems.com/technical-data-sheet/caf2-calcium-fluoride/
NaCl:
https://www.spectral-systems.com/technical-data-sheet/nacl-sodium-chloride/
KBr:
https://www.spectral-systems.com/technical-data-sheet/kbr-potassium-bromide/
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