Raman Spectrography

Raman Spectrography uses the principle of “Raman Scattering” for CO₂ measurement. The gas sample is aspirated into an analyzing chamber, where the sample is illuminated by a high intensity monochromatic argon laser beam. The light is absorbed by molecules which are then excited to unstable vibrational or rotational energy states (Raman scattering). The Raman scattering signals (Raman light) are of low intensity and are measured at right angles to the laser beam. The spectrum of Raman scattering lines can be used to identify all types of molecules in the gas phase. Raman scattering technology has been incorporated into many newer anesthetic monitors (RASCAL monitors) to identify and quantify instantly CO₂ and inhalational agents used in clinical practice.4