Infrared absorption at 10.6 mum in CO(2) at elevated temperatures

Extended high temperature measurements of absorption at 10.4 microm in CO(2)

Measurements of absorption by the P(14)-P(24) 10.4-microm CO(2) laser transitions have been performed at 200 Torr at temperatures from 540 to 775 K. Using these results plus earlier data, empirical curves describing the absorption coefficients as a function of temperature are determined over the temperature range from 295 to 775 K. Comparison of model predictions with experiment is made and a discussion of the divergence between them is given.

Absorption of 9.6-micron CO2 laser radiation by CO2 at elevated temperatures

Absorption of 9.6-micron CO2 laser radiation by CO2 at temperatures between 296 and 625 K has been measured at a pressure of 200 Torr. Experimental results for the R1O-R26 and P1O-P28 transitions have been obtained and compared with computed values of absorption. The relative optical broadening coefficients due to He and N2 have been measured on the R16-R22 and P16-P22 transitions over the same temperature range.

Diesel particle mass concentration by optical techniques

Particle mass concentrations in the exhaust streams of a variety of Diesel engines have been measured using both a visible wavelength opacity meter and an IR photoacoustic device. We present real-time recordings of the emissions from vehicles operated over the Federal Test Procedure driving cycle. Steady-state mass concentrations of a few mg x m(-3) can be measured by opacity and as low as 0.4 mg x m(-3) by the photoacoustic technique, but the uncertainty is approximately 15% in both cases. An uncertainty of approximately 20% is found in the estimation of total mass emission rates over the Federal Test Procedure cycle by integration of the optical signals.

High temperature 10.4-microm absorption in CO(2)-He-N(2) mixtures

Absorption coefficient measurements in CO(2)-He-N(2) mixtures have been performed over the 295-650-K temperature range at four wavelengths of the 10.4-microm CO(2) laser transition. Calculated values of the absorption coefficient were compared with the measured values for fifteen gas mixtures and agreed to >10%. A gas mixture interpolation scheme allows an accurate estimation of absorption by gas mixtures other than those on which measurements were made. A less accurate but simpler interpolation method, dependent only on the fraction of C0(2), is also discussed for determining the absorption coefficient.

High temperature absorption in the 10.4-mum band of CO(2)

The absorption coefficient of pure CO(2) has been measured as a function of temperature in the 295-650 K range for the P(14)-P(24) and R(10)-R(24) laser transitions. Cubic curves fitted to the experimental results are given to allow interpolation at all temperatures within the range. The P(20) transition shows an anomolously high value of absorption. Variation of absorption coefficient with pressure was linear but small for all transitions in the 200-700-Torr pressure range at three temperatures. Calculations of the absorption coefficient are performed and compared with experimental data.