I will get water peak around 3500 region in broad peak, how can I remove the peak?
The references to dehumidifying or pumping aren't relevant here. They'd remove peaks due to water vapor, which are recognizable as a forest of very narrow peaks. Since you say you have a single broad peak it must be liquid water. To answer how to remove it, I'd need to know the composition and thickness of your sample, the height of the absorbance peak and the spectral resolution of your spectrum.
in the FTIR Spectrim device there must be dehumidifier
There will stil some peaks for water vapor which you can deal with it by the software according to the device you are using.
But in any case remember to dry your sample at 85C for 24 hr before FTIR test
Several ways:
1) To find the source of water and remove it. (for example to pump FTIR system)
2) measure water peak as background and normalize the spectrum (if water sours is sable)
3) simulate water contribution
I had the same problem and fitted an an adapter to the sample chamber and attached to a vacuum. Check the climate control setting of the room to keep room humidity low. Finally, if you are doing spectral analysis, you can exclude this band region from analyse if your peak signals for your of analtyes of interest are in different band regions.
The references to dehumidifying or pumping aren't relevant here. They'd remove peaks due to water vapor, which are recognizable as a forest of very narrow peaks. Since you say you have a single broad peak it must be liquid water. To answer how to remove it, I'd need to know the composition and thickness of your sample, the height of the absorbance peak and the spectral resolution of your spectrum.
I guess you mean the n(OH) band (stretching mopde/H-OH) of liquid water.
If so, do you have also a weaker band at around 1640 cm-1 ?
If so, this band is assigned to the d(OH) band (scissoring mode/H-O-H) of water.
What you could do for removal:
Transfer your spectrum of your sample in water in absorbance mode (if not done already). Measure spectrum of pure liquid water and transfer also in absorbance mode.
Try to subtract your spectrum of pure liquid water from your spectrum of sample in water by a scaling factor (Use respective tools in your software. Bruker has good one e.g.) with the condition of flat baseline in the region 3700-3000 cm-1 and/or 1700-1600 cm-1.
You will probably not fulfill both, but you get an impression, if any underlying bands from your substance you are interested in, will appear.
Good success,
Martin
It will be better if you purge the FTIR instrument with dry liquid nitrogen gas.
If purging isn't an option, like if you are doing reflectance and the attachment is to big to purge effectively you can manually digitally this process is not perfect though.
1. Measure a spectrum of what ever your background is as a sample.
this should produce a flat line that is all at 1 except at the water lines and the CO2 feature.
2. subtract that spectrum from 1
1-(y values)
to produce a spectra that is all 0's or really close to zeros except at the water and CO2 lines.
3. multiply these values by some constant and add/subtract the results to your sample spectra. typical values I have used are between 0.02 and 0.1
4. change the constant until you have minimized the water vapor.
Note this has to be repeated for each sample and likely you will need a different constant for each measured spectra you have because the water vapor concentration can vary in your sample compartment.
also note that this method will likely not result in the removal of the CO2 band AND the water vapor contribution.
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