We investigate the accuracy of temperature measurements by coherent anti-Stokes Raman spectroscopy (CARS) of O2 and use measurements taken with N2 CARS and a thermocouple for comparison. Scanning vibrational CARS spectra of O2 and N2 were recorded over a broad range of temperatures: between 294 K and 1900 K in air that was heated in a tube furnace and at approximately 2450 K in a fuel-lean CH4–O2–N2 flame. Temperatures were derived from least-squares fits of simulated and experimental spectra. Both the fundamental vibrational band and the first hot vibrational band were included in fitting. In the case of the tube furnace, the N2 and the O2 CARS temperature measurements agreed to within 3%, and results were similar with the thermocouple; in the flame the agreement was to within 1%. We conclude that, for cases in which O2 is present in sufficient concentrations (≈10% or greater), the accuracy of O2 thermometry is comparable with that of N2.
© 2001 Optical Society of America
Original Manuscript: May 15, 2000
Revised Manuscript: August 23, 2000
Published: February 20, 2001
Thomas A. Reichardt, Paul E. Schrader, and Roger L. Farrow, "Comparison of gas temperatures measured by coherent anti-Stokes Raman spectroscopy (CARS) of O2 and N2," Appl. Opt. 40, 741-747 (2001)