Interference of Molecular Absorption Bands and Selection of the Best Spectral Regions for Laser Based Analysis of Molecular Gases

Abstract

The interference of the absorption bands of H₂O, CO₂, and several gaseous biomarkers was analyzed in the middle and near-IR spectral region using the HITRAN2006 database. One of the objectives of the study was to demonstrate an algorithm of the selection of the best spectral regions for laser based analysis of molecular gases in the case of strong interference of molecular absorption bands. It was demonstrated that the problem of the vibration-rotation band interference for detected and interfering gases is aggravated in the near-IR spectral region. This aggravation is caused not only by the decrease in the absolute band intensity for overtones and combination bands of the molecular vibrations but also by the relative increase in the absorption in H₂O lines and high density of CO₂ lines in the near-IR spectral region.