title: Time-resolved in situ detection of CO in a shock tube using cavity-enhanced absorption spectroscopy with a quantum-cascade laser near 4.6 µm.
abstract: Cavity-enhanced absorption spectroscopy (CEAS) using a mid-infrared DFB quantum-cascade laser is reported for sensitive time-resolved (10 μs) in situ CO measurements in a shock tube. Off-axis alignment and fast scanning of the laser wavelength were used to minimize coupling noise in a low-finesse cavity. An absorption gain factor of 91 was demonstrated, which enabled sub-ppm detection sensitivity for gas temperatures of 1000-2100K in a 15 cm diameter shock tube. This substantial improvement in detection sensitivity compared to conventional single-pass absorption measurements, shows great potential for the study of reaction pathways of high-temperature combustion kinetics mechanisms in shock tubes.
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: Shengkai
authors.initials: S
authors.lastname: Wang
authors.forename: Ritobrata
authors.initials: R
authors.lastname: Sur
authors.forename: Xing
authors.initials: X
authors.lastname: Chao
authors.forename: Jay B
authors.initials: JB
authors.lastname: Jeffries
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Hanson