Operating procedure:

A classical operating procedure is as follows:

Steps in getting an FT-IR spectrum of the sample along with interferometer

1. In the first step, an interferogram is recorded without any sample in the beam and saved in computer memory. This interferogram is features of the experimental set up and consists of the response of the spectrometer in terms of the performance of source, interferometer, or the detector. This so also known as background spectrum also involves the contribution from any ambient water and carbon dioxide present within the optical bench.

2. The interferogram is recorded again; this time with a sample introduced into the beam and also stored in computer memory. It holds signals from the sample and the background air or solvent.

3. The first interferogram is subtracted from the second along with the help of a computer.

4. The resulting difference interferogram is then Fourier transformed to provide the spectrum.

Within the procedure of taking the difference between the two interferograms the absorption since of atmospheric gases is also removed.