ABSTRACT
In the chapter, are firstly recalled particular points regarding the apparatuses used in infrared spectroscopy. Then, the chapter is developed for the contribution of this method to the qualitative analysis and especially to the functional analysis. The parts of a UV-visible spectrophotometer and those of an infrared are analogous. The sources of radiation IR can be a Nernst filament or a globar for mid-infrared. The dispersion element can be a diffraction grating operating from the near IR until UV or a monochromator. The receptor is an essential part of the spectrophotometer, because of the smallness of the energy to measure. It is a thermocouple. The reception is made with the help of a Fourier transform and in turn with that of a Michelson‘s interferometer. Absorption IR spectra are used to identify pure substances, particularly organic ones. IR spectra contribute widely to establishing developed formulas via the identification of the present functional groups. The contribution of the method to the quantitative analysis is weak.
