3. Experimental protocols for obtaining IR spectra

In this section, we present methods for obtaining the spectrum of a sample according to its nature (liquid, gas, solid, powder, film, etc.). Three questions underlie each analysis.

• Should we determine the concentration of a known species that we know may be present in the sample being analyzed?

  As the spectral fingerprint of the desired species is known, the spectroscopic analysis must be as sensitive as possible, either to achieve trace concentrations, or to obtain reliable, fine precision of the quantity of material monitored. In the first case, the aim is to improve the detection limit, while in the second case the aim is to achieve the highest possible repeatability and reproducibility. However, it is by no means necessary to seek high spectral resolution or very high accuracy in terms of wave numbers....