In situ combustion measurements of CO_2 by use of a distributed-feedback diode-laser sensor near 20 µm

Abstract

High-resolution absorption measurements of CO 2 were made in a heated static cell and in the combustion region above a flat-flame burner for the development of an in situ CO 2 combustion diagnostic based on a distributed-feedback diode laser operating near 2.0 m. Calculated absorption spectra of hightemperature H 2 O and CO 2 were used to find candidate transitions for CO 2 detection, and the R͑50͒ transition at 1.997 m ͑the 1 ϩ 2 2 ϩ 3 band͒ was selected on the basis of its line strength and its isolation from interfering high-temperature water absorption. Measurements of spectroscopic parameters such as the line strength, the self-broadening coefficient, and the line position were made for the R͑50͒ transition, and an improved value for the line strength is reported. The combustion-product populations of CO 2 in the combustion region above a flat-flame burner were determined in situ to verify the measured spectroscopic parameters and to demonstrate the feasibility of the diode-laser sensor.

Line strengths of 12C16O2: 4550–7000cm−1

“…The agreement is significantly improved if the comparison is constrained to include only those studies published since 1999, suggesting that the empirical intensities from the more recent studies are more consistent. For example, the comparisons shown for seven bands [29,34,[37][38][39][41][42][43][44] in Table 13 yield a mean difference within 0.6 % of the present values. However, our S v for the 20012-00001 band at 4977.8 cm À1 is 1.5% lower than reported by other recent studies, most of which measured a few lines with laser spectrometers.…”

“…The results of the analysis of those line strengths are included in Table 2, except for some of the entries for which the authors provided only a small number of line strengths which were too few to analyze. The values of (o À c)% from these nominal studies [41][42][43][44][45] are included in last columns of Table 9 [41-43] and the last two columns of Table 11 [44,45]. The numbers for upper state J in Table 2 are often larger than the transitions shown in Tables 6-12.…”

Self-broadened widths and shifts of 12C16O2: 4750–7000cm−1

“…These included the R26 transition of 20013 ‹ 00001 reported by Zeninari et al [9]; 21 transitions of 20012 ‹ 00001 reported by Corsi et al [10,11]; 3 R-branch transitions in 20012 ‹ 00001 by Webber et al [12]; 11 lines between P28 and R28 in 30013 ‹ 00001 by Hikida et al [13] and 10 lines between P20 and P2 in the 30013 ‹ 00001 band by De Rosa et al [14]. The most extensive laser data of 12 C 16 O 2 self-broadening were reported by Henningsen and Simonsen [15] who measured 38 transitions in the 30012 ‹ 00001 band from P20 to R52.…”

Measurements of NH_3 and CO_2 with distributed-feedback diode lasers near 20 µm in bioreactor vent gases

“…Because these high-resolution measurements had smaller uncertainties than those listed in HIT-RAN96, we consider the measured values to be an improvement. The measured line strengths for the CO 2 transition at 5007.787 cm Ϫ1 were previously published 12 and are listed in Table 2.…”