Conclusion

Infrared absorption spectrometry

Figure 1 - Molecular energy levels at the frequencies (or energies) of different photon spectral ranges

Figure 2 - Interatomic binding energy of a diatomic molecule in a qualitative Morse-type model. Vibrational levels are represented by the horizontal lines

Figure 3 - Description of a classical mechanical oscillator around its resonant frequency, arbitrarily set at a pulse of 500 Hz.

Figure 4 - Diagram of the elongation modes of a tetrahedral molecule

Figure 5 - Combination transitions

Figure 6 - Example of a vibration-rotation spectrum of methane gas

Figure 7 - Infrared absorption spectrum of a diamond single crystal (Laurent Massi thesis, Nantes)

Figure 8 - Schematic diagram of a Michelson interferometer

Figure 9 - Transmission-mode infrared gas measuring cell

Figure 10 - Quantitative analysis of solutions. Determination of cell thickness

Figure 12 - Variations in the real part of the refractive index of water in the mid-infrared range

Figure 13 - Total reflection

Figure 14 - Schematic diagram of an infrared measurement using specular reflection-absorption.

Figure 15 - Schematic diagram of a diffuse reflection assembly

Figure 16 - PIR spectrum of a sample of pure silica powder under controlled humidity obtained by diffuse reflection (Carteret thesis 1999 Nancy Univ)

Figure 17 - Optical diagram of the infrared microscope

Figure 18 - Optical diagram of the grazing lens, based on Cassegrain optics, and optical diagram of the ATR lens.