Study of CO2 spectroscopic parameters at high temperature near 2.0 μm

Abstract

Reliable spectroscopic parameters of probed species at high temperature, such as line strengths, self-broadening coefficients, air-broadening coefficients, and temperature exponents, are important in absorption spectroscopy for accurately studying species properties, such as temperature, concentration, speed, and their corresponding field distributions. However, parameters from widely used database such as HITEMP are mainly theoretical calculation results, and there exist considerable errors compared with the results in actual situations. In order to validate spectroscopic parameters of CO2 lines used in combustion diagnosis, CO2 spectrum is recorded as a function of temperature in a range between 700 K and 1300 K in experiment using a distributed feed-back diode laser. Parameters of each line are deduced, such as line strengths, self-broadening coefficients and temperature exponents. The relative errors between measured and calculated line-strengths are less than 11% at 5006.978 cm-1 and 5007.7874 cm-1. The measured self-broadening coefficients at different temperatures and temperature exponents are conducive to the detection of CO2 concentration in combustion diagnostics.