TY - JOUR
T1 - Time-resolved continuous-filtering Vernier spectroscopy of H2O and OH radical in a flame
AU - Lu, Chuang
AU - Vieira, Francisco Senna
AU - Schmidt, Florian M.
AU - Foltynowicz, Aleksandra
N1 - Publisher Copyright:
© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
PY - 2019/10/14
Y1 - 2019/10/14
N2 - We use broadband near-infrared continuous-filtering Vernier spectroscopy (CF-VS) for time-resolved detection of H2O and OH radical in a premixed CH4/air flat flame. The CF-VS spectrometer is based on a femtosecond Er:fiber laser, an external cavity that contains the flame, and a detection system comprising a rotating diffraction grating and photodetectors. Spectra of H2O and OH radical around 1570 nm are continuously recorded with 6.6 GHz spectral resolution, 4.0 × 10−7 cm−1 absorption sensitivity, and 25 ms time resolution, while the fuel-air equivalence ratio is periodically modulated with a square wave. The concentrations of the two analytes are retrieved with percent level precision by a fit of a Vernier model to each spectrum spanning 13 nm. The temporal profiles of both concentrations in each modulation cycle are repeatable and the steady-state concentration levels are in good agreement with predictions based on one-dimensional simulations of a static flat flame. The robust CF-VS spectrometer opens up for quantitative monitoring of multiple products of time-varying combustion processes with relatively simple data acquisition procedures.
AB - We use broadband near-infrared continuous-filtering Vernier spectroscopy (CF-VS) for time-resolved detection of H2O and OH radical in a premixed CH4/air flat flame. The CF-VS spectrometer is based on a femtosecond Er:fiber laser, an external cavity that contains the flame, and a detection system comprising a rotating diffraction grating and photodetectors. Spectra of H2O and OH radical around 1570 nm are continuously recorded with 6.6 GHz spectral resolution, 4.0 × 10−7 cm−1 absorption sensitivity, and 25 ms time resolution, while the fuel-air equivalence ratio is periodically modulated with a square wave. The concentrations of the two analytes are retrieved with percent level precision by a fit of a Vernier model to each spectrum spanning 13 nm. The temporal profiles of both concentrations in each modulation cycle are repeatable and the steady-state concentration levels are in good agreement with predictions based on one-dimensional simulations of a static flat flame. The robust CF-VS spectrometer opens up for quantitative monitoring of multiple products of time-varying combustion processes with relatively simple data acquisition procedures.
UR - http://www.scopus.com/inward/record.url?scp=85073615450&partnerID=8YFLogxK
U2 - 10.1364/OE.27.029521
DO - 10.1364/OE.27.029521
M3 - Article
C2 - 31684212
AN - SCOPUS:85073615450
SN - 1094-4087
VL - 27
SP - 29521
EP - 29533
JO - Optics Express
JF - Optics Express
IS - 21
ER -