title: Time-Resolved Broadband Cavity-Enhanced Absorption Spectroscopy behind Shock Waves.
abstract: A fast and sensitive broadband absorption technique for measurements of high-temperature chemical kinetics and spectroscopy has been developed by applying broadband cavity-enhanced absorption spectroscopy (BBCEAS) in a shock tube. The developed method has effective absorption path lengths of 60-200 cm, or cavity enhancement factors of 12-40, over a wavelength range of 280-420 nm, and is capable of simultaneously recording absorption time profiles over an ∼32 nm spectral bandpass in a single experiment with temporal and spectral resolutions of 5 μs and 2 nm, respectively. The accuracy of the kinetic and spectroscopic measurements was examined by investigating high-temperature reactions and absorption spectra of formaldehyde behind reflected shock waves using 1,3,5-trioxane as a precursor. The rate constants obtained for the thermal decomposition reactions of 1,3,5-trioxane (to three formaldehyde molecules) and formaldehyde (to HCO + H) agreed well with the literature data. High-temperature absorption cross sections of formaldehyde between 280 and 410 nm have been determined at the post-reflected-shock temperatures of 955, 1265, and 1708 K. The results demonstrate the applicability of the BBCEAS technique to time- and wavelength-resolved sensitive absorption measurements at high temperatures.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Matsugi
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST) , 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
authors.forename: Hiroumi
authors.initials: H
authors.lastname: Shiina
authors.affiliation: Department of Environmental and Life Sciences, Toyohashi University of Technology , 1-1 Hibarigaoka, Tenpaku-cho, Toyohashi 441-8580, Japan.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Oguchi
authors.affiliation: Department of Materials and Life Sciences, Sophia University , 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Takahashi