Diode-laser absorption measurements of CO_2 near 20 μm at elevated temperatures

A diode-laser sensor system based on absorption spectroscopy techniques has been developed for nonintrusive measurements of CO(2) in high-temperature environments. Survey spectra of the CO(2) (20 degrees 1,04 degrees 1)(I)-00 degrees 0 and (20 degrees 1,04 degrees 1)(II)-00 degrees 0 bands between 1.966 and 2.035 mum (4915-5085 cm(-1)) were recorded at temperatures between 296 and 1425 K in a heated static cell and compared with calculated spectra (by using the HITRAN 96/HITEMP database) to find candidate transitions for CO(2) detection. High-resolution measurements of the CO(2) R(56) line shape [(20 degrees 1,04 degrees 1)(II)-00 degrees 0 band] were used to determine the transition line strength, the self-broadening half-width, and the coefficient of temperature dependence of the self-broadening half-width. The results represent what are believed to be the first measurements of CO(2) absorption near 2.0 mum with room-temperature diode lasers. Potential applications of the diode-laser sensor system include in situ combustion measurements and environmental monitoring.