1. Laser optical spectroscopy and Raman spectrometer

Molecular spectroscopy is based on the phenomenon of light-matter interaction. Light radiation carries energy (the energy of a photon is inversely proportional to its wavelength) which can be absorbed by the irradiated material. These mechanisms are described schematically in figure 1 . When the photon has an energy corresponding to the energy difference between the fundamental quantum state of a molecule and one of its excited quantum states, a resonance phenomenon occurs, with a transition from the fundamental to the excited state. For low-energy photons, i.e. for the micrometer wavelengths of infrared radiation, the quantum levels considered correspond to molecular vibrations.