Inverse fitting direct absorption spectroscopy Technology: Simplified implementation and enhanced performance.

The conventional direct absorption spectroscopy (DAS) technique has been plagued by the difficulty of obtaining accurate baseline, which is caused by photoelectric drift and the absence of non-absorbing regions in the transmitted light intensity signal. An inverse fitting direct absorption spectroscopy (IF-DAS) technique has been proposed to address this difficulty. The technique leverages the intrinsic nonlinear intensity response of tunable lasers to achieve baseline-free concentration measurements.

Shock Tube Measurement of the CH + CH → CH + CH Rate Constant.

The rate constant for the CH + CH → CH + CH reaction was studied behind reflected shock waves at temperatures between 1369 and 1626 K and pressures from 8.6 to 47.4 atm in mixtures of methane, ethane, and argon.

Shock Tube Measurement of the CH + H ⇔ CH + H Rate Constant.

The rate constant for the reaction CH + H ⇔ CH + H was studied behind reflected shock waves at temperatures between 1619 and 1948 K and pressures near 10 atm in a mixture of CH, CH, H, and argon. CH time histories were measured using laser absorption of a CO gas laser near 10.53 μm.