Final answer:
In FTIR spectroscopy, background and sample interferograms are converted to spectra using Fourier transform. The spectrum obtained from the background interferogram is subtracted from the spectrum obtained from the sample interferogram to identify the absorption properties of the sample.
Step-by-step explanation:
In FTIR spectroscopy, both the background and the sample interferograms are converted to spectra using Fourier transform. The spectrum obtained from the background interferogram is then subtracted from the spectrum obtained from the sample interferogram to identify the absorption properties of the sample.
By subtracting the background spectrum, we can isolate the specific absorption signals caused by the sample. This allows us to determine the presence or absence of key functional groups in the sample molecule.
For example, if a carbonyl bond absorbs in a certain frequency range, but the sample spectrum does not show absorption in that range, we can infer that the molecule does not contain a carbonyl group.