Principle : The Raman spectroscopy is the inelastic scattering of light by molecules, that is to say, the broadcast involving the exchange of energy light-material.
The analysis is done by excitation of the material. raised to an energy level virtual by a powerful light source to be monochromatic type laser, it reémet then a write-off which is collected and then analyzed by a detector to be adequate. this radiation consists of two types of signals. the very first of the majority corresponds to the rayleigh scattering : the incident radiation is scattered elastically with no change of energy and therefore wavelength. however, photons in a very limited number of cases can interact with matter. it absorbs ( or transfers ) of energy to the photons, thereby producing the radiation, the stokes (anti-stokes). the energy variation observed at the photon provides information on the energy levels of rotation and vibration of the molecule concerned.