In-situ measurement of pyrolysis and combustion gases from biomass burning using swept wavelength external cavity quantum cascade lasers

Abstract

Broadband high-speed absorption spectroscopy using swept-wavelength external cavity quantum cascade lasers (ECQCLs) is applied to measure multiple pyrolysis and combustion gases in biomass burning experiments. Two broadly-tunable swept-ECQCL systems were used, with the first tuned over a range of 2089-2262 cm(-1) (4.42-4.79 mu m) to measure spectra of CO2, H2O, and CO. The second was tuned over a range of 920-1150 cm(-1) (8.70-10.9 mu m) to measure spectra of ammonia (NH3), ethene (C2H4), and methanol (MeOH). Absorption spectra were measured continuously at a 100 Hz rate throughout the burn process, including inhomogeneous flame regions, and analyzed to determine time-resolved gas concentrations and temperature. The results provide in-situ, dynamic information regarding gas-phase species as they are generated, close to the biomass fuel source. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement