Pure rotational coherent anti-Stokes Raman spectroscopy in mixtures of CO and N2.
We present a model for quantitative measurements in binary mixtures of nitrogen and carbon monoxide by the use of dual-broadband rotational coherent anti-Stokes Raman spectroscopy. The model has been compared with experimental rotational coherent anti-Stokes Raman scattering spectra recorded within the temperature range of 294-702 K. Temperatures and concentrations were evaluated by spectral fits using libraries of theoretically calculated spectra. The relative error of the temperature measurements was 1-2%, and the absolute error of the CO concentration measurements was <0.5% for temperatures < or =600 K. For higher temperatures, the gas composition was not chemically stable, and we observed a conversion of CO to CO2. The influence of important spectroscopic parameters such as the anisotropic polarizability and Raman line-broadening coefficients are discussed in terms of concentration measurements. In particular, it is shown that the CO concentration measurement was more accurate if N2-CO and CO-N2 line-broadening coefficients were included in the calculation. The applicability of the model for quantitative flame measurements is demonstrated by measuring CO concentrations in ethylene/air flames.
Afzelius
Mikael
M
Lund Institute of Technology, Lund 22100, Sweden. mikael.afzelius@forbrf.lth.se
Brackmann
Christian
C
Vestin
Fredrik
F
Bengtsson
Per-Erik
PE
D000465:Algorithms; D002248:Carbon Monoxide / Q000032:analysis* / Q000737:chemistry; D045424:Complex Mixtures / Q000032:analysis* / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry; D009904:Optical Rotation; D010865:Pilot Projects; D013059:Spectrum Analysis, Raman / Q000295:instrumentation / Q000379:methods*; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*
D045424:Complex Mixtures; D002248:Carbon Monoxide; D009584:Nitrogen