Mid-infrared polarization spectroscopy of polyatomic molecules: Detection of nascent CO2 and H2O in atmospheric pressure flames

We report the application of mid-infrared polarization spectroscopy (IRPS) for detection of nascent CO2 and H2O in atmospheric pressure flames. The recorded IRPS spectra demonstrated both the quantitative nature of the method and the suppression of strong infrared emission from flames. In spite of the high line-density of the hot polyatomic ro-vibrational spectrum, lines belonging to different CO2 and H2O hot bands were recognized in the chosen spectral region, which ensures the species-selective application of IRPS.